We’re alive! Thanks to photosynthesis!

Hello everyone,

Source: Photo of my plants by me

Today I’m going to try to explain to you all about photosynthesis. It is something that is happening in my flat right now with all the new herbs and flowers I have started growing in April. I have a lot of information about photosynthesis that I want to share with you so this might end up being a 2 part post. There’s no time to waste so let’s get going!

Photosynthesis is one of the most vital functions on earth and we would not be alive without photosynthesis and the plants produced as a result of it. It is a chemical reaction that takes place in the leaves of green plants and although the name is long, the equation for photosynthesis is quite simple.

Source: Khan Academy

It’s carbon dioxide, water, and light energy that reacts together to produce glucose and oxygen. If you read my previous post about ATP, you will have read that the equation for photosynthesis is the reverse equation for cellular respiration. And that is so interesting and fascinating to me that our bodies need the products of photosynthesis to create energy and survive, and plants also need the products from our bodies creating energy to survive and grow! How cool is that?

Photosynthesis occurs in the chlorenchyma tissue in a plant. The chlorenchyma tissues are mostly found in the leaves and the 2 layers of the chlorenchyma tissues are the upper palisade mesophyll and the lower spongy mesophyll. The upper palisade mesophyll layer contains about 80%  of the chloroplasts, which is specifically where photosynthesis occurs. The lower spongy mesophyll layer has loosely arranged cells with abundant air spaces as you can see in the diagram below.

Source: Printable Diagram

Going back to the photosynthesis equation, water is a crucial part of plant growth and you probably know that if you’ve even ever attempted to grow a plant yourself. You would be surprised though that only 1% of the water absorbed by plants is used for photosynthesis. However, that 1% of water used for photosynthesis is quite important in that a shortage of water for the plant will end up indirectly limiting photosynthesis to occur. This is because the lack of water will make the stoma/stomata(pores) of the plant to close which decrease the amount of carbon dioxide the plant is being supplied with for photosynthesis.

Source: Fortune City

Light energy is just as important to water, for photosynthesis and again, you probably know that if you have any experience with growing plants yourself. The sun’s energy reaches the earth in the form of electromagnetic radiation which consists of waves and particles. Those particles are known as photons, the smallest divisible unit of light and can also be referred as a single light quantum. We are going to go a bit into physics to talk a bit about electromagnetic radiation but bare with me now.

Each photon carries a certain amount of energy which determines how much the photon vibrates. The distance of how much a photon moves during one of its vibration is called a wavelength, measured in nanometers. Electromagnetic radiation spans a wide spectrum of wavelengths with gamma rays at one end of the spectrum with wavelengths of 5-10nm, and radio waves at the other end of the spectrum with wavelengths of 1012nm.

Source: Waves Revision

The interesting part about electromagnetic radiation is that only a small part of this huge spectrum can be seen with the human eyes. This is spectrum is between the wavelengths 380-750nm, different wavelengths of visible light being perceived as color. And in plants, the chlorophyll does not absorb the green color part of the spectrum which is then reflected from the plant, visible for us humans to see.

Where are the chlorophylls in plants then? They’re in this tiny bean looking sacs called the chloroplast mostly found in the upper palisade mesophyll layer of the chlorenchyma tissues. There are 2 membranes enclosing a gelatinous matrix called the stroma, not be confused with the stoma.

Source: Scitable

As you can see, suspended in the stroma are these membranous sacs called thylakoids, that can be stacked into piles called grana. It is estimated that there are approximately 500 thousand chloroplasts per square millimeter of a leaf, so we’re talkin’ really small here. Now let’s dig deeper into how photosynthesis occurs in this tiny organelle!

There are 2 phases to photosynthesis, the light reaction phase, and the Calvin cycle phase. The light reaction phase occurs in the thylakoid membranes of the chloroplast where light energy produces energy in the form of ATP and NADPH2. The Calvin cycle phase, however, occurs in the stroma using the energy from the light reaction phase to capture atmospheric carbon dioxide to produce glucose.

The light reaction is a light dependent reaction which means it cannot function without light energy. There are 2 photosynthetic units called the photosystem 2(P680) and the photosystem 1(P700) in the light reaction phases. These units collect light energy and pass on the energy as a stream of electrons. The electrons originate from water molecules where they get split into electrons and hydrogen ions which help release oxygen as a waste product from the plant. The reason we can breathe. Once oxygen is released, the concentration of hydrogen ions in the thylakoid membrane start to increase. This makes the hydrogen ions want to leave the thylakoid membrane making their way towards the ATP synthase where the energy from the hydrogen ions is used to produce ATP. This energy is used to drive the next phase, the Calvin cycle phase in the stroma of the chloroplast.

Source: Khan Academy

The Calvin cycle/ Calvin-Benson cycle is also known as the dark reaction cycle because light energy is not directly used in this cycle. I know, so many different names for one cycle! But it’s quite stupid to call this the dark reaction because the energy received from the light dependent phase is very short lived and therefore this cycle only happens during the day when the sun it up. So calling the Calvin cycle the dark reaction may confuse people into thinking the dark reaction happens at night. But anyways, the energy from the light reaction phase processes carbon dioxide to combine with 5 carbon sugars, resulting in a net gain of glyceraldehyde 3-phosphate.

Source: Boundless

 

 

 

 

 

 

 

This is what the two phases of photosynthesis look like and I know there are lots of details I did not go through but there are some more details on the Calvin cycle that I would like to go through. The process of Calvin cycle I have explained is the C3 photosynthesis. This is because the 1 carbon molecule from the carbon dioxide and the 5 carbon sugar molecules from the sugars combine together with the help of a catalyst, RuBisCo, to form rubilose which is a compound that is unstable and quickly splits into a 3 carbon compound, hence the C3. But sometimes the RuBisCo will attach oxygen instead of carbon dioxide to the sugar molecule, resulting in a series of reactions that loses carbon and energy. RubisCo is also an inefficient catalyst in that it can only catalyze 3 molecules per second compared to other catalysts that catalyze thousands per second. Therefore plants contain a high amount of RuBisCo which is thought to be the most common protein in the world.

But how does photosynthesis occur for hot weather plants? These plants have to close their stomata to conserve water so they cannot get as much carbon dioxide needed for photosynthesis. Well, not to worry, there are plants called C4 plants that have their own ways of photosynthesis. C4 plants have an enzyme called PEP carboxylase to help capture carbon dioxide which gets stored in the plant’s bundle sheath cells. The RuBisCo can then work with the carbon dioxide that has been isolated from oxygen, avoiding the tendency to wastefully attach oxygen to the sugar molecules.

Source: Hammiverse

There is another form of photosynthesis for plants such as cacti, orchids, and succulents that live in very hot climates. It’s similar to C4 photosynthesis but the stomata will stay closed during the day and stay open at night to gather carbon dioxide. This carbon dioxide then gets stored as malic acid in the vacuoles, getting converted back to carbon dioxide when needed.

I know this has been long a post but hang in there, I’ve just got a few more things I want to share because I want to finish this post in 1 part. Maybe go make yourself a little green smoothie with greens that have gone through photosynthesis?

In the thylakoid membrane and grana of chloroplasts, there are several types of chlorophyll molecules. The structure of those molecules are similar to hemoglobins found in our blood, but instead of the central atom of that molecule being iron, it’s magnesium instead. There is a range of different pigments which allow plants to harvest a broader spectrum of light. The most common are chlorophyll a, then chlorophyll b and carotenoids. Carotenoids give off autumn colors such as yellow, orange, and red which can be seen in dead tree leaves, carrots, and tomatoes etc. Carotenoids protect plants against photo-oxidation which is why lots of herbicides contain high levels of carotenoids.

And that is it guys! Whew. Thanks for sticking around if you got to this point. I hope this post was useful in that it gave you a new appreciation for plants and the food we get to eat thanks to photosynthesis. See you in my post! Till then!

xx

 

ATP= Energy, but what does it stand for?

Hello world!

Today I am going to be explaining to you how energy is made in our body. Cool right? So make sure you’ve got enough energy to read through this post!

Before we jump into what ATP is, let’s go through the physiological processes that we go through so we can produce ATP. What is respiration? Respiration is the action of breathing and there are 3 types of respiration that are constantly happening in our bodies. First is external respiration. External respiration occurs in the lungs by diffusing oxygen into the blood stream and diffusing carbon dioxide out from the bloodstream when you breathe in and out. Then there is internal respiration. Internal respiration is an exchange of gasses between the cells of the body and the blood stream. It’s the same concept to external respiration but in your cells, not your lungs. And lastly, there is cellular respiration. Cellular respiration is the act of making ATP in a specific organelle of the cell, the mitochondria. It is how we derive energy from the foods that we eat.

What is respiration? Respiration is the action of breathing and there are 3 types of respiration that are constantly happening in our bodies. First is external respiration. External respiration occurs in the lungs by diffusing oxygen into the blood stream and diffusing carbon dioxide out from the bloodstream when you breathe in and out. Then there is internal respiration. Internal respiration is an exchange of gasses between the cells of the body and the blood stream. It’s the same concept to external respiration but in your cells, not your lungs. And lastly, there is cellular respiration. Cellular respiration is the act of making ATP in a specific organelle of the cell, the mitochondria. Actually, only 2/3 of the production of ATP occurs in the mitochondria but more on that later. Cellular respiration is basically is how we derive energy from the foods that we eat.

External and internal respiration is highly related to our pulmonary/respiratory system so I will explain it further when I post about the pulmonary system. Instead, let’s focus on cellular respiration today. The equation for cellular respiration is this.

Source: Cronodon

When I said that cellular respiration is how we derive energy from food, that food specifically meant glucose. And as you can see in the equation above, glucose is the only form of food that reacts with oxygen to produce energy so it makes sense that we as humans enjoy pasta, chips, sweets, and even sugary drinks. Oxygen, on the other hand,  is not something we obtain through consumption but through respiration. This is why I mentioned external and internal respiration earlier. Without oxygen, we cannot produce energy even if we have an abundance of glucose in our system so I’d say it’s pretty important we continue to breathe.

When glucose and oxygen react, the product they produce is water, carbon dioxide, and energy. The water produced gets recycled throughout your cells and the carbon dioxide leaves your body through internal, then external respiration. The energy, however, is like the currency our body requires to be able to move, grow, think, and everything else really. That currency is the topic of this post, ATP.

ATP stands for “Adenosine Triphosphate”. Its structure is comprised of a nucleotide in the form of adenosine, a sugar molecule in the form of ribose, and 3 phosphate molecules, hence the triphosphate. And as you can see in the

Source: Energy in Living Things

diagram, the energy is stored between in the phosphate molecules, in their covalent bonds that hold the phosphates together. So when the body requires energy, the covalent bond between the outermost phosphate and the center phosphate will break, releasing energy. ATP is then no longer ATP because it doesn’t have the triphosphate. So instead, it’s then called ADP- adenosine diphosphate.

 

Once ATP becomes ADP, is it useless then? No, ADP will eventually gain another phosphate with the help of some energy and become ATP once again as stored energy. And thankfully this is a continuous cycle because this means our bodies can efficiently gain energy without having to produce ATP from scratch every time we go to the gym.

Source: Spark Notes

How does ATP get produced then? Well there are 3 major steps for making ATP. Glycolysis, Krebs cycle, and oxidative phosphorylation or also called electron transport chain. Glycolysis is the first step to making ATP which is an anaerobic process. It is when a glucose molecule gets broken down into smaller pyruvate molecules in the cell’s cytoplasm, and 2 ATPs can be produced at this stage. After glycolysis is the Krebs cycle, also known as the citric acid cycle which is an aerobic process that occurs in the mitochondria of the cell. This is when pyruvate molecules get reworked to create 2 ATPs per glucose molecule. And lastly, during oxidative phosphorylation which is also an aerobic process, 34 ATPs are produced again in the mitochondria. You will notice that most of the ATPs are produced during aerobic cycles because of the presence of oxygen. This is because for example when you are performing high-intensity exercises and start running out of breath, your body cannot go past the glycolysis stage but instead goes through a side process of fermentation producing lactic acid which is the chemical that gives you pain when you try to do one too many lunges. It’s your body’s way of telling you to lay down and catch your breath. But anyways, 1 glucose molecule can produce up to 38 ATPs and this is the basics of how ATP is produced through cellular respiration.

There are other elements that go into ATP production but those are a bit more advanced and I have not learned the details of it so I will write about it when I do! Anything related to cells is difficult for me to understand since I cannot visualize it but I hope this post was easy to understand and in the next post I will write about photosynthesis which is actually the reverse equation of the cellular respiration equation! Till then y’all!

xx

 

Let’s talk about food!

Hello everyone!

Let’s talk about food, let’s talk about F-O-O-D! Yes, food does get me excited. *stomach growls* What are the major food groups that we consume everyday? But first, let’s talk metabolism.

We talk about having slow or fast metabolism all the time. But what does metabolism actually mean? Metabolism is the sum of the processes in the buildup and destruction of the organelles of cells. In other words, the breaking down and build up of stuff in a cell. You could also define metabolism as the chemical changes in living cells by which energy is provided for vital processes and activities, while new material is assimilated. For example, let’s think about cows. Cows only eat grass but those cows end up as steak for our Valentine’s Day dinner. It’s the process of grass getting broken down to become meat that is called metabolism.

In any living organism, there is always two parts to metabolism. Catabolism and anabolism. Catabolism means to break down, and anabolism means to construct stuff. So remember that catabolism+anabolism=metabolism.

Now that we know what metabolism actually means, let’s finally move on to talk about food.

There are 3 primary food groups that you hopefully consume everyday. Carbohydrates, lipids, and protein. This is a photo of some chicken soup I made the other day and let’s go through the food groups in this soup. There are some carbohydrates in the form of vegetables and a bit of rice I put in the soup, protein in the form of some chicken, and a bit lipid floating on top in the form of some olive oil I used for sautéing my mirepoix. We consume these naturally occurring forms of our major food group everyday so it must be important, right? Well if you agree, let’s learn a bit more about them, shall we?

Carbohydrates. The scary freaky carbs that I thought was the short cut to weight gain during my teenage years. But let’s take a look at carbohydrate from a  molecular level. It is always composed of 3 elements; carbon, hydrogen, and oxygen. The smallest/simplest unit of carbohydrates is in the form of a sugar called monosaccharide. You may have heard of glucose (also called dextrose), fructose, and galactose which are all different molecules of monosaccharides. When two monosaccharides are covalently bonded together, they form what is called a disaccharide. 2 glucose molecules bonded together are called maltose, a glucose and a galactose molecules bonded together is called lactose, and a glucose and fructose molecules bonded together is called sucrose.

Source: Chemistry 240

 

There are some common properties that mono and disaccharides share together. You probably noticed that all the words of these molecules end with the suffix -ose, which means that it’s a sugar molecule, so therefore they obviously taste sweet. They are also soluble in water contrary to the insoluble polysaccharides that I will be explaining now. You may have guessed that polysaccharides probably have many monosaccharides bonded together, and you would have guessed correctly. Polysaccharides are many units of monosaccharides linked together by glycosidic bonds that help with storing energy. A common form of a polysaccharide is the bunch the glucose molecules called cellulose.

You may have guessed that polysaccharides probably have many monosaccharides bonded together, and you would have guessed correctly. Polysaccharides are many units of monosaccharides linked together by glycosidic bonds that help with storing energy. A common form of a polysaccharide is the bunch the glucose molecules called cellulose which is an indigestible polysaccharide because humans do not have not appropriate enzymes to break them down. But most of our polysaccharides are consumed in the form of starch which is digestible. Starch is found in plants and is used as food that helps with slow releasing energy compared to another form of a polysaccharide, glycogen. Glycogen is the stored form of glucose in the liver and muscles, which gives fast access to energy because it is easier to breakdown than starch. I will explain in a future post about how glucose is converted to energy when I write about ATP.

Let’s move on to proteins. The holy grail for gaining muscle that we always talk about when we are in a conversation with a vegan individual. “How do you get your protein then?” Seriously, I’m not a vegan but stop asking that to vegans, people. Anyways, protein molecules are made up of 4 elements; carbon, hydrogen, oxygen, and nitrogen. Its monomer is called amino acid, and there are 20 different types of amino acids. Out of the 20, 9 are essential amino acids that our body requires but cannot produce. And as we know, proteins are important for forming muscle, hormones, and enzymes in the body. I don’t have to go through sources of protein, right?

Source: TutorVista

I mentioned that monomers of protein are amino acids. So when do amino acids become protein? Protein is formed when amino acids are bonded together. But before amino acids become protein, if between 2-50 amino acids are bonded together, they are called peptides. Polypeptides are when there are 50-100 amino acids bonded together and finally protein is formed when over 100 amino acids are bonded together. And the bonds between the amino acids are called peptide bonds.

Source: ACGS

And last but not least of our major food group, lipids. Lipids, also known as fats, are also comprised of carbon, hydrogen, and oxygen like carbohydrates, but in different structures which do not allow them to be water soluble. There are 2 types of lipids. Saturated and unsaturated lipids. The difference between saturated and unsaturated fats depend on their molecular structure. It all depends on whether or not the carbons in the lipid molecules are bonded once or twice to the carbon next to it. As you can see in the diagram, the unsaturated lipid molecule has two carbons that are bonded together twice. These differences in the molecular structure give the lipids different properties. Saturated fats are often solid at higher temperatures like butter, cocoa butter, or coconut oil. Unsaturated fats, however, have more distance between the molecules, therefore are often liquid at room temperature. Such as olive oil, truffle oil, and sesame oil. Also, unsaturated fats can sometimes form into trans-unsaturates fats which are denser than normal unsaturated fats. These trans fats are dangerous for your health because of its unique chemical structure and I will explain this when I start my chemistry revision in 1 week.

Source: Unknown

There are 3 types of lipids; triglycerides, sterols (cholesterol), and phospholipids. Cholesterol and phospholipids are what cell membranes are made of. Triglycerides are lipids you obtain from food that stores energy in your bodies main fat storage site, adipose tissues. Triglycerides are composed of glycerol and 3 fatty acids bonded together as you can see in the diagram here. Triglycerides have many different types and the types are mainly divided by whether they are saturated or unsaturated. However, sometimes triglycerides are in the form of polyunsaturated fats which means that they have more than one double-bonded pair of carbon in its molecular structure.

So that is it for our major food group guys. Hope this was an interesting post as food is such a big part of our lives. Next time I will be writing about how these foods we consume end up being used for energy. Till then!

xx

 

Let’s be honest, what do Hormones actually do??

Hello to you internet peeps!

I am going to be writing about the endocrine system and hormones today. I had no idea of what the endocrine system’s function was until I learned about it a few months ago! So crazy to think how little knowledge I had about the human body until I started university. I even thought I had more knowledge about the human body than the general public because I used to do ballet but I was so so wrong! I think it’s true when people say that the more you learn, the more you realize how much you don’t know about anything! But let’s embrace the fact we don’t know anything and learn something new today!

So what is the endocrine system? The endocrine system is basically hormonal communication. It is an important part of any animal’s internal communication system and any animal’s hormone producing cell constitutes its endocrine system.

What are hormones then? Hormones are chemical messages sent from endocrine cells through the bloodstream to target ‘cells’ where these messages are processed and integrated into a cellular response. These chemical messages play an important role in regulating the internal environment of the organism. But like sending any message to anyone, it is important to only send messages when required. We’ve all been there being annoying by texting tons of emojis to our loved ones which do no good to anyone really. And it is the same with hormones but with more serious physiological circumstances. All hormones are produced in endocrine glands (endocrine organs so to say) that usually have an effect in other parts of the body but in most cases, the endocrine glands are controlled by the hypothalamus via the pituitary glands. The messages that different hormones send to many different areas of the body are meant to be widespread and longer-lasting regulatory actions compared to the messages being sent in the nervous system. This is why even though the endocrine system has a similar job to the nervous system, it has completely different ways of communicating and functioning in the body. Hormones mediate responses to environmental stimuli, regulate growth, development, and reproduction while the nervous system responds to sensory stimuli.

How does the endocrine system communicate through hormones then? Well, it’s like sending a text message or sending a post via the Royal Mail. It’s as simple as that. Actually, not quite as simple but the general idea of communication is simple. The sender being myself in this instance sends a text message (the communication channel) to my sister, the receiver, asking for pictures of my dog Tory. She will then read the message and send me a few snaps of my adorable dog Tory like this one!

Apologies for the not so subtle photo attachment! More photos of my dog will pop up on this blog every once in a while as I am one proud dog mom! But going back to my point, the previous example was to help you understand the general idea of how the endocrine system communicates to the rest of the body.

Let me give you a more specific example of how the endocrine system communicates. You just had a delicious piece of chocolate cake and the beta cells in your pancreas detect your increase in blood glucose concentration. The pancreas being an endocrine gland, will send some insulin through your bloodstream to the liver telling it to increase its uptake of glucose. The liver will then receive that message through insulin and get to work by converting glucose to glycogen, resulting in your blood glucose level decreasing to its normal level.

But besides from insulin, there are so many different hormones that if I were to tell you about all the hormones, I would have to spend the whole day on my desk! But what I can tell you is the 3 major classes of hormones and a few examples of those hormones. The different classes depend on the hormone’s molecular structure. The first class is the amine hormones based on the amino acid tyrosine they have. A few examples of amine hormones are epinephrine, norepinephrine, and thyroxine which are all hydrophilic. The next class is the peptide hormones. Peptide hormones have very distinctive chains of amino acids and these hormones are also hydrophilic. Most hormones in our body are peptide hormones and few example of them are oxytocin, insulin, and growth hormone. Last but not least, the third class is the steroid hormones made from cholesterol and is the only class of hormone that is hydrophobic. Estrogen, testosterone, aldosterone are all examples of steroid hormones.

Source: Wikipedia

And as I mentioned earlier, peptide and amine hormones are hydrophilic while steroid hormones are hydrophobic. This makes a difference in how the hormones reach a cell. The membranes of cells are made of lipids which do not allow for hydrophilic molecules get across them. So as you can see in the diagram below, the left illustration is a target cell for hydrophilic hormones that has its receptor on the outside of the cell membrane so the hormone doesn’t have to go through the cell membrane. Hydrophobic steroid hormones, however, can go across the cell membrane so the target cells for steroid hormones have receptor proteins inside the cell. Once the hormones activate the target cell, it alters the activity of the target cell by increasing or decreasing some of its functions.

Source: StudyBlue

Because of these differences in water solubility, peptide-based hormone’s signals are often more transient and may sometimes alter gene expression. Steroid hormones, however, tend to be longer lasting and mostly alter gene expression.

Let’s move on to the endocrine system as a whole and learn about some of the endocrine glands that we have in our body.

Source: Serior

Silly as it may sound, endocrine glands are glands of the endocrine system that produce hormones and secrete them directly into the bloodstream. Our endocrine glands are the hypothalamus, 2 pituitary glands, thyroid gland, parathyroid gland, 2 adrenal glands, gonads(testes or ovaries), and sort of the pancreas, the thymus, and the pineal gland.

The hypothalamus and the pituitary glands are located in our brain. This particular location links our endocrine system with the nervous system for certain situations. And the cells of the hypothalamus actually look like neurons in the nervous system. As you can see in this diagram, the hypothalamus kind of holds to the testicle looking pituitary glands. The pituitary glands looking like testicles means that there are two parts to it. The anterior pituitary gland and the posterior pituitary gland. The hypothalamus controls hormones produced by the pituitary gland so to remember this, I think of the hypothalamus having the upper hand on the pituitary glands since it is also anatomically above the pituitary glands.

Some of the hormones released by the hypothalamus are dopamine and corticotropin-releasing hormone. The anterior pituitary glands have 6 releasing and inhibiting hormones such as growth hormones and thyroid hormones. The posterior pituitary gland, on the other hand, acts as a storage to release oxytocin and antidiuretic hormones for when the body requires high amounts of it.

The next gland is the thyroid and parathyroid gland. The thyroid and the parathyroid glands are located by your larynx in your neck region. It produces hormones that help with increasing metabolism of most body tissues. It also plays a big role in providing you with normal growth and development. The thyroid glands produce thyroid hormones thyroxine and triiodothyronine, and also produce calcitonin and the parathyroid hormone which helps with decreasing or increasing calcium ions in your blood for homeostasis.

Source: Fitlife

Moving on to the adrenal glands that sit on top of your kidneys. The adrenal glands respond to short-term and prolonged stress. When someone is experiencing short-term stress, the stress filled nerve impulses go to the hypothalamus in the brain where it sends signals down going through the spinal cord, down the preganglionic sympathetic fibers to the adrenal medulla in your adrenal gland. The adrenal medulla will then produce amine hormones called catecholamines that help increase your blood pressure and metabolic rate, convert glycogen to glucose for energy and releases that glycogen to the blood stream. The way in which the adrenal gland react to prolonged stress, however, is slightly different. When prolonged stress signals are sent to the hypothalamus, the hypothalamus will produce corticotropin releasing hormones to the anterior pituitary gland telling it to release corticotropin to the adrenal cortex of your adrenal glands. The adrenal cortex will then release mineralocorticoids which help your kidneys retain sodium and water while also increasing your blood volume and pressure. The adrenal cortex will also release glucocorticoids which help to convert protein and fats to glucose for energy, increase your blood glucose levels, and suppress your immune system.

Source: Studylib

Now the testes and ovaries, the gonads! Our precious reproductive organs! And yes you’ve probably guessed correctly that the gonads produce sex hormones. Estrogen and progesterone are examples of sex hormones produced in the female ovaries and the testes in men produce testosterone.

Although I mentioned the pancreas, the thymus, and the pineal glands, they are not really official endocrine glands so I won’t be talking about them today. I will when I properlly learn about them though!

Thanks if you’ve made it to this long post and I hope everything I said was east to understand. Next time I will be talking about our major food groups. Till then guys!

xx

Homeo-what??

Hello internet!

Today I’m going to write about homeostasis. If you don’t know what this means, don’t worry.  I actually didn’t know what is was until I started university last September! I remember so vividly, asking the girl next to me what homeostasis was while being so embarrassed! But now I know what is so let’s get started!

Homeostasis is the tendency to maintain a constant internal environment. Homeo meaning ‘same’, and stasis meaning ‘stable’. Whether the internal environment may be the inside of my dog Tory or the aloe plant I’m growing, homeostasis is extremely important for keeping any organism alive and well. For example, if my dog Tory is hot and thirsty, she will start panting to get rid of her excess heat and also to let me know she needs some water because otherwise, she would be dehydrated and at worst, slowly start to die. And if my aloe leaves didn’t droop to tell me it needs some water every week, it too would eventually die from lack of water. The panting and drooping are all healthy signs that those organism’s homeostasis is functioning properly.

Another way to express homeostasis is dynamic equilibrium. This means the environment is in a state of balance between continuing processes. This is possible through our body’s communication systems, the endocrine and nervous system. These systems work around a cycle of the variable, receptor, control center, and effector. The variable is the factor that is being controlled or regulated like temperature or blood pH levels. Next, the receptor is the structure that monitors the changes in the environment and sends that information to the control center where it will be determined what the normal state should be of that variable. Then lastly, the effector receives instructions from the control center and carries it out to the variable to maintain homeostasis forming a cycle of homeostasis as seen below.For example, if the variable were to be your body temperature, the cells in your skin would be the receptors that then send signals to your brain saying that you are too hot. The brain being the control center in this scenario, would then decide what to do with that information. Unless you have any neurological issues, your brain would tell your exocrine glands to open up your sweat glands to let your body cool down to maintain your homeostasis in body temperature.

Continuing on from the same scenario, say you went and stood by your freezer with the door open to cool yourself down. Your sweat glands are open to cool your body from the inside while you are standing next to a bag of frozen peas to cool your body from the outside. It wouldn’t take long till your body cools down to your desirable temperature however, you end up standing next to your frozen bag of peas for a bit too long and now you are cold. What would happen then? Your sweat glands would close to retain your body heat and your brain would tell your skeletal muscles to start shivering to raise your body temperature as seen below.

Source: Pinterest

Does the concept of homeostasis seem complicated so far? No, it’s pretty quite simple and straight-forward, right? Or at least I hope it is! So moving onto negative feedback.

Most examples of homeostasis are examples of the negative feedback system. Negative feedback is when the control mechanism (the control center) responds to stimuli with actions to restore its original equilibrium. Like your body opening your sweat glands to restore your temperature down to its original state. The effector, your brain, moves the variable in the opposite direction of the stimuli, going in the direction of hot to cold. These reactions require both the involvement of your nervous system and your endocrine system which prevents sudden and severe changes.

There are times though when need an extra boost in hormones for certain situations. This is when the positive feedback system comes into play during catastrophic events like childbirth or blood clotting.  Sorry guys, you don’t get to join in on all the fun for this one. But anyways, positive feedback is a temporary system that works by responding to stimuli by amplifying it during processes that need completion. For example, you can see below a diagram of positive feedback during childbirth. When the baby’s head pushes on the mother’s cervix during childbirth, that sends signals through the neurons to the brain. Those signals tell the pituitary gland to release more oxytocin to help with uterine contractions which will lead to the baby’s head pushing on the mother’s cervix even more. This action then creates a cycle of positive feedback to help the mother with childbirth until the baby finally pops out!

Source: Khan Academy

 

And that is it for homeostasis y’all! It’s not a huge topic which was nice for me to write about but I hope that I was still able to explain things clearly. My next post will be on the endocrine system, talking all about hormones and endocrine glands! Till then!

xx

 

Our Brain Box! Or is there more than just the brain?- Part 2

Hello world!

Another week, another blog post!

Today I’m going to finish going through all the material that I have learned on the nervous system. There are bits coming up that I am worried about having to explain it in an easy way to understand, but I can’t always pick and choose what I want to do. Am I right?

Let’s get going then!

I finished the previous post by going through all the divisions and the subdivisions of the nervous system, where they are found in the body, and what roles they have. Today I’m going to talk about the different cells that are found throughout the nervous system and how information in received.

Source: Wikipedia

I think most people have a general idea of what nerve cells look like. Long branch-shaped cells in the brain with light flashing here and there. That was my extent of knowledge on nerve cells before I properly learned about them in university. But it turns out those branchy looking cells have such an amazing physiology going on inside of them at all times!

In the nervous system, there are 2 types of cells. Neurons and glial cells. Neurons, as shown above, are the cells we most commonly think of when we think of nerve cells. They are the cells responsible for receiving and sending signals. Neurons are highly specialized to conduct cell nerve impulses through electrical cell signaling. Neurons are also very special in that they are amitotic, which means they cannot regenerate, however, they have the extreme longevity to make up for being amitotic. Another interesting fact about the neurons is that most of the cell bodies of these neurons are located in the CNS! This means that a single neuron can easily be the length of your toes to you back! Crazy! This explains why a horrible back injury can lead to the loss of use in the lower body.

Source: Unknown

 

As you can see above, there are 3 different types of neurons. Motor, inter, and sensory neurons. The different types of neurons depend on where the cell body is located. The first type is the motor neurons, also known as multipolar neurons, which are the most common and biggest nerve cell of them all.  They have 1 axon with their cell body located very close to the abundance of dendrites; their main functions are to carry signals from the CNS to the rest of the body. Interneurons, also known as bipolar neurons, are quite rare compared to motor neurons. They also have 1 axon but 1 dendrite attached to the cell body. Impulses from the interneurons move between sensory and motor neurons in the CNS. And lastly, sensory neurons, also known as unipolar neurons are commonly found in the sensory receptors, which are in the PNS. They have more than one dendrite and axon in which the cell body is located between the 2 axons. Sensory neurons transmit impulses from sensory receptors to the CNS.

Although these neurons look different and have different functions, every neuron has 3 things in common. They receive information through the dendrites which are the shorter branch looking bits. The received information then passes down through the long axon, then to the longer branch-looking axon terminal where dendrites from other neurons are positioned very close to receive information.

Moving onto the glial cells!

Glial cells are basically cells that help and protect neurons. There are roughly 9 times more glial cells than neurons because glial cells do reproduce. So say for example someone has a brain tumor, those tumor cells would be formed by glial cells, not neurons. This is why brain tumors are called gliomas. In the first diagram with the big neuron, you can see the blue Schwann cells (a type of glial cell) wrapped around the axon and some other types of glial cells in the diagram below. These different glial cells all have different functions in the nervous system, hence the different shapes and sizes. For example, microglial cells help with immune defense, Schwann cells insulate and protect the neurons, while oligodendrocytes build up the myelin sheath which I will explain soon. These glial cells, however, are only found in certain divisions of the nervous system. Astrocytes and microglial cells are neuroglial cells meaning they are found in the CNS. The rest are not neuroglial cells meaning they can be found in the PNS.

Source: Dreamstime

Because Schwann cells, that build up to be the myelin sheath have lots of important functions, I am going to go more in depth about what they do. Schwann cells wrap around axons of neurons kind of like a swiss roll or a sushi roll I guess?Yes, I know my current hunger is reflecting on my writing style. But anyways, this insulates the axon and helps increase the speed of which nerve impulses pass through the axon. In the CNS, oligodendrocytes have this role for the axons in the neurons, and in the PNS is where Schwann cells have this role. As you can see in the diagrams above, there is always more than one Schwann cell wrapped around an axon. And between those Schwann cells are tiny gaps called nodes of Ranvier. These nodes help nerve impulses jump from one node to the next, through saltatory action (like a frog jumping on lily pads to cross a stream) which is very energy efficient for the neuron sending the nerve impulse.

Now onto synapse. What is synapse? It is the end of the action potential. What is action potential then? Well, because I didn’t properly learn about action potential yet, here is a link to a great video explaining action potential: https://www.youtube.com/watch?v=OZG8M_ldA1M&t=516s. If you don’t know what action potential is, I highly recommend you watch this video before reading through what I will be explaining next!

Do you understand what action potential is now? Let’s get going then!

Synapse occurs after the action potential and there are electrical and chemical synapses. Electrical synapses send signals much more quickly because the electrical signal does not get chemically translated and therefore is less efficient than chemical synapses. Chemical synapses are a bit slower than electrical synapses however, they are more efficient, precise, selective, and common. So I will be focusing on chemical synapse today. Synapse occurs when action potential stimulates the release of neurotransmitters(chemical signals) from vesicles at the axon terminal that then diffuses across the synaptic cleft(or gap) to deliver its message. The arrival of action potential opens the voltage-gated calcium ion channels which allow external calcium ions to flow into to the neuron. Calcium ions entering the neuron causes the neurotransmitter containing vesicles to fuse with the presynaptic membrane and release their contents into the synapse.

Source: Antranik

As you can see in the diagram above, neurotransmitters are protected by the synaptic vesicles which carry them down to the cell membrane. You will then notice that once the neurotransmitters reach the cell membrane, they are no longer inside the synaptic vesicle to diffuse across the synaptic cleft. The diffused neurotransmitters then attach to the neurotransmitter receptors in the postsynaptic neuron which starts the action potential for the postsynaptic neuron. If my explanation was not clear, here is a video link that explains synapse very well: https://www.youtube.com/watch?v=L41TYxYUqqs.

Now that I have finished explaining about the synapse, let’s take a few steps back to the PNS. As I mentioned in my previous post, the PNS controls sensory neurons. These sensory neurons have sensory receptors that are specialized to respond to stimuli. There are different types of sensory receptors to respond according to the 5 types of stimulus or sense. The first receptor is the mechanoreceptor which responds to the sense of touch. Any types of stimuli from pressure, itch, vibration, to stretch. The next is the thermoreceptor and yes, it responds to changes in temperature. Then comes the photoreceptor which responds to light. The chemoreceptors respond to chemicals and pH, and last but not least, nociceptors respond to potential danger that can be interpreted as pain. One thing to keep in mind about the sensory receptors is that the sensation of whatever you are experiencing does not happen in the sensory receptors. The receptors simply receive the sensory information and send it to the brain to perceive the sense.

And that is it people! This post ended being my longest one yet as I was trying to avoid writing another post on the nervous system so I do apologize for the great length of this post. I hope this is helpful and easy to understand and I’ll come back soon with a surprise subject!

xx

Our Brain Box! Or is there more than just the brain?

Hello again internet friends!

Today I’m going to be talking about the nervous system. I know it seems like such a big subject but I’m gonna try to go through everything I learned in two posts so I can get on with posting about all the systems before my exam in May. My brain is already in agony… But I know I can do it! So shall we begin?

When you think of the nervous system, what do you think of? Before I learnt anything about the nervous system I would’ve said the brain and nerves. I wouldn’t have been wrong but there is so much more to the nervous system than that! The nervous system is so incredibly complex but also incredibly fascinating and I’m going to try to teach you how it works from what I have learnt.

Source: Brain and neurons painted by me

The nervous system’s main job is to receive information via our sensory receptors. It then has to quickly translate that information in the brain to immediately tell our bodies how to respond to the information that has been received. For example, if you touched a hot pan by accident, the touch receptors in your hands would send a message to your brain saying that the object you are holding is too hot to touch. Your brain would then translate that message and tell the muscles in your hands to immediately take your hand away from the hot object that is causing you pain. This is what I would say if I were to tell a 5-year old about the nervous system. But, since I am not 5-years old and because I’m guessing you aren’t either, let’s go more in-depth about the nervous system.

If you were to look at the nervous system in a big picture, it would be divided into two parts. The central nervous system (CNS) and the peripheral nervous system (PNS). The CNS comprises your brain and spinal cord, and the PNS are all the nerves that spread out from the CNS that aren’t part of the brain or the spinal cord. It’s kind of like the CNS being a tree trunk and the PNS being the roots or the branches that spread out from the trunk. Both have very important roles in the human body and we could not live without one or the other.

Source: ayUCar

 

As you can see in this giant diagram above, the PNS has lots of subdivisions. The PNS controls the motor neurons and the sensory neurons, and it is the motor neurons that get divided into the somatic and autonomic division of the nervous system. The somatic division is where you have control over your movements and the autonomic division is where you don’t have control over your movements such as your stomach. You don’t think about digesting the foods you ate because the autonomic division does it for you. And in the autonomic division are the last two subdivisions, the sympathetic and the parasympathetic division. The sympathetic division comes to work when you are in the fight or flight mode. For example, if you were to be walking along a sidewalk on a sunny day and suddenly see a huge spider, you would immediately let out a few bad words and jump or run away from it. The parasympathetic division starts doing its job when you are in a relaxed state away from the danger of stepping on a spider, the rest and digest mode. It lets your body do the digestion it forgot to do while you were running away from that spider and also reminds you that you were on your way to go for a wee.

So now that I have gone through the different systems and the subdivisions of the nervous system, let’s dive in a bit more deep into the CNS.

As I mentioned earlier, the CNS consists of the brain and the spinal cord. It interprets sensory information being put in and also commands responses to the rest of the nervous system. It will command responses based on past experiences, reflexes, and current conditions.

Like for instance, if you get bitten by a dog, at that moment your reflexes tell you to take your hands away from the dog. When you see that dog again, your brain tells you not to go near it from your past experience. But now the dog is very calm, wagging its tail at you, wanting to be loved. Then your brain thinks “hmm, maybe it’s okay to pet the dog now”, so you’ll go over to the dog and start petting it. This is an example of how the CNS commands responses.

Source: ASU School of Life Sciences

Moving on to the anatomy of the brain which is where most of the CNS does its job. As you can see above, the brain can be divided into 5 parts with 1 extra non-official part. The different parts consist of  4 different lobes and the cerebellum which actually looks a bit different from the rest of the brain. The 4 lobes are the frontal, parietal, temporal, and occipital lobe. Each lobe controls different functions such as the occipital lobe controlling the functions of vision and temporal lobe controlling functions for hearing and facial recognition. I won’t go through all the functions of the lobes since you can see them all in the diagram.

Now shall we talk a bit more about the PNS? But before we do, I’m going treat myself with some brain looking walnuts, to get me going.

Source: CNX

Okie dokie, let’s move on the PNS. As mentioned earlier, the PNS consists of everything in the nervous system but the brain and the spinal cord. But what are they then? They are all the peripheral nerves, their ganglia(collection of nerve cell bodies), and sensory recpetors. Your sense of touch, taste, smell, hearing, and vision in your body? It’s all from the nerves that are a part of your PNS. I also mentioned earlier that the PNS gets divided into two subdivisions, the autonomic and somatic division in which the autonomic division gets divided again into the sympathetic and parasympathetic subdivisions. In the autonomic and somatic subdivisions, there are somatic fibers that supply nerves to the skeletal muscles, and autonomic fibers that supply nerves to the smooth & cardiac muscles and glands. I am wildly guessing that there are autonomic fibers in the muscles and glands for when we are in a fight or flight more or a rest and digest mode to control what our muscles do but I don’t recall going through the details of this in my lectures so I am going accept the fact as it is for now.

I think I am going to stop here before moving on to the cells in the nervous system. The nervous system was a big subject that I was scared to dive into at first so I understand if you feel the same way after reading this. But, I do hope that at least some of the information I explained was easy to understand. It’s challenging for me to try to teach a subject that I am not yet an expert in, but writing these blog posts are really helping me a lot so I aim to continue doing it! Till then!

xx

Our Body’s Built-In Filter- Part 3

Hello, internet friends!

It’s been a while since my last post because I took some time off in the countryside spending time cooking great food and bonding with 2 beautiful border collies. But I am ready to get back into revision mode for my upcoming exam in May!

So shall we begin? I finished off my last post with going through how the nephron in the kidneys turn blood into urine

To have a bit of a recap, blood is forced into the glomerulus where fluids in the blood are forced out into the bowman’s capsule. The fluids then travel through a long series of tubules that have different functions of reabsorbing different nutrients back into the blood. The filtered fluids which are now urine,  goes through the collecting duct which then passes out of the kidney, travels down the ureter, and gets collected in the bladder. The urine then leaves the body through the urethra to its final destination, the toilet!

I’ve gone through a lot of information in the past two posts about the urinary system but there is still some more material I would like to go through regarding tiny details of how fluids are pushed out into the glomerulus and how nutrients get reabsorbed into the blood capillaries.

If you read my post from before, you will be aware that blood travels from the renal artery to the afferent arteriole, into the glomerulus. The blood that has not been pushed out into the glomerulus will then exit the glomerulus through the efferent arteriole. Well, it turns out that the efferent arteriole has a smaller lumen than the afferent arteriole!  But why is that? This is because the decrease in the size of the lumen will increase the pressure in the glomerulus which helps the fluids in the blood to get pushed out into the bowman’s capsule.

However, the fluids in the blood don’t just get pushed out into the bowman’s capsule. Because of the three different pressures of the Net Filtration Pressure (NFP), some nutrients that have been pushed out, will get pulled back into the glomerulus. This is the first to producing urine which is called glomerular filtration. The different pressures are the glomerular hydrostatic pressure, osmotic pressure, and capsular hydrostatic pressure. I struggled a bit to understand how these pressures work so I am not 100% confident in explaining this but I will try my best for easy understanding!

Source: APSU Biology

As you can see in the diagram, the GHP pushes fluids out into the bowman’s capsule while the OP and CHP push fluids back into the glomerulus. The OP pushes water in the fluids back into the blood. The CHP works in a similar way but other molecules in the fluid will also get pulled back in. This is where I struggled so, please do understand if you don’t understand what I am about to explain! The CHP is not the same as the OP because this pressure is caused by the GHP. For example, if you were to blow into a bowl of flour, some of the flour will blow back into your face (this has happened a few times for me while baking)! The CHP works in a similar way. Because there is pressure pushing outwards, there is also a bit of pressure that occurs in the opposite way. Or at least that is how I understood it after going through different educational sources to understand how it works. And since the CHP is caused by GHP, the pressure is not as strong. In fact, the OP is not as strong as the GHP either, and this is good because otherwise there would be no fluids to go through the tubules to produce urine!

So to calculate the total NFP, the formula is GHP-(OP+CHP)=NFP which is 10mm Hg(milligrammes of mercury).

If the first step of urine production is glomerular filtration, what is the second step? As we know that the filtered fluids in the bowman’s capsule travel through a long series of tubules to reabsorb nutrients, the second step to urine production is tubular reabsorption. This is when different nutrients from the fluids get reabsorbed back into the blood capillaries, depending on which part of the tubules the fluids are travelling through. But how do the nutrients move from the tubules to the blood capillary? Well, there are two ways. The nutrients can be reabsorbed through a paracellular or transcellular movement. Paracellular movements require nutrients to go in between two tubular cells and the transcellular movement require nutrients to go through a single tubular cell. There are a lot more detail into how the nutrients go through the cells but I have not learnt the specifics yet so I will explain this hopefully next year when I study physiology more in depth!

Source: Unknown

So this is about it for the urinary system! I know it is a lot of information on just one system of the human body so I’m hoping that I will be able to cover each system under 2 blog posts in the future. I have to say, it is like writing an essay for me so it’s quite challenging but it is definitely helping me a lot! And to help myself with my upcoming exam, I’m going to try to type some of the keywords in the urinary system without looking at my notes. Some of the major keywords are: renal artery & vein, afferent & efferent arteriole, glomerulus, bowman’s capsule, distal convoluted tubule (DCT), descending and ascending limbs of loop of Henle, proximal convoluted tubule (PCT), the collecting duct, renal calyxes, renal pyramid, nephrons, kidneys, ureter, bladder, urethra, peristalsis, renal medulla, renal cortex, and the renal pelvis. I may have left out a few words but I’d say these are the major keywords to know if you are studying the urinary system.

I hope that all my explanations have been easy to understand and if you are reading this, please let me know what you think of it! In the next post, I will be explaining about the nervous system . Till then!

xx

Our Body’s Built-In Filter- Part 2

Hello again!

I’m going to try to finish writing about the urinary system in this post today but there is quite a lot more material to cover so we’ll see how it goes!

So where were we…  I finished going through the basic functions and anatomy of the main organs of the urinary system last time. In this post, I will focus more on the details of how the kidneys filter out our blood to urine. It is quite a fascinating subject in my opinion so this will be fun going through all the details again! You will appreciate your wee so much more after this post (I hope)!!😆

If you have read my earlier post, you should know that the key organ of the urinary system, the star of the show,  are the bean-shaped kidneys. The kidneys are where blood is filtered out into the urine, maintaining our homoeostasis in blood pressure, blood pH, water, electrolytes, and red blood cell production. The kidneys also eliminate waste products such as nitrogenous wastes, toxins, and drugs through the urine.

Nephron drawing by me

The nephron is the functional unit of the kidneys and that is where all the filtration occurs and there are about a million nephrons per kidney! If I had to very briefly explain how the filtration occurs in each nephron, I would say that blood is forced through very narrow blood vessels where some of the fluid gets squeezed into a tube. That fluid then travels through a long tube giving away its nutrients if necessary, which results in urine.  That is basically how urine is produced but there is so much more than that!

Source: Educast

Firstly, let’s begin with blood entering the nephron. I’m not sure if I mentioned this before but anything “renal” has to do with the kidneys. Why did I say that? It is because the blood enters the nephron via the renal artery. It then goes through the afferent arteriole entering the glomerulus. The rest of the blood then exits the glomerulus through the efferent arteriole.

However,  when blood reaches the glomerulus, some fluids in the blood are pushed out into the bowman’s capsule where the filtration begins. As you can see in the diagram below, the filtered fluids start travelling from the bowman’s capsule through a long tube which has different parts and names to it. The fluids travel through the proximal convoluted tubule (PCT), down the descending limb of the loop of Henle, up the ascending limb of the loop of Henle,  through the distal convoluted tubule (DCT), and finally to the collecting duct.

As the filtered fluids travel through the different tubes with different functions, the fluids get filtered even more as it reaches the collecting duct.  Starting from where the fluids first get filtered, the bowman’s capsule is responsible for catching the fluids from the glomerulus.

Then the next stop is the PCT. This is where most of the water in the fluid, bicarbonate ions, all of the glucose, amino acids, and most of the sodium, chlorine, and potassion ions are reabsorbed into to the blood capillaries depending on the current status of the body. If the water concentration in the blood capillaries is lower than the water concentration in the PCT, water will get reabsorbed to the blood capillaries through passive transport, which does not require any energy. However, when all of the glucose and amino acids molecules including some of the ions get reabsorbed, it is not through passive transport but rather active transport. This requires energy in the form of ATP which is why the simple cuboidal epithelial cells of the PCT have lots of mitochondria. Since there is a lot of reabsorption that occurs in the PCT, the inner lining of the cells have lots of tiny hair-like extensions called villi. The villi are there to help increase the surface area of which reabsorption can take place. And in the cell membranes of the PCT, there are tiny channels or holes to let the reabsorbed material into the cells so it can eventually reach the blood capillaries. There are two ways in which this happens, but I will explain that towards the end.

Phew!💦That was one long paragraph on such a small part of the nephron! You might want a short break from reading this as there is still a lot to go through!

Okie Dokie, let’s move on!

After travelling through the PCT, the fluids reach the loop of Henle. Since the loop of Henle is always in the shape of a ‘U’, the two parts are called the descending (going down) and ascending(going up) limbs of the loop of Henle. The loop of Henle also has simple epithelial cells like the PCT but it has fewer villi. I’m guessing this is because the loop of Henle has fewer substances it reabsorbs so there is no need for lots of villi. In the descending limb, water again will get reabsorbed depending on the body’s needs, decreasing the water concentration in the fluids. Since the water concentration has decreased in the descending limb, when the fluids reach the ascending limb, there is a higher concentration of sodium, chlorine, potassium, magnesium, and calcium ions in the tubule. This allows the magnesium and calcium ions get reabsorbed through passive transport, while the sodium, chlorine, and potassium ions get reabsorbed through active transport. The methods of which the ions get reabsorbed are different but doing so, the water and ion concentration in the fluids become more neutral.

Once the fluids travel through the loop of Henle, the fluids reach the DCT. The cells of the DCT again have the same type of cells as the other tubules mentioned before but they do not have villi. Once the fluids reach the DCT, there aren’t many substances available to be reabsorbed than hormones and some last minute reabsorption of water. The hormones that are reabsorbed are aldosterone -a steroid hormone, the antidiuretic hormone, and the parathyroid hormone which are both peptide hormones. These are all hormones that are related to water regulation in the body. The reabsorption of hormones will depend on the body’s current status and is a very complicated process so I will write about it when I learn about it!😅

Once the fluids have finished going through the DCT, it’s urine now! Whoop whoop! The freshly made urine travels to the collecting duct where it receives urine from other neighbouring nephrons. Also at this stage, if the body needs even more water, some water can be reabsorbed for the last time before it travels to the renal pyramid, to the major calyxes, and down the ureter, to the bladder.

So that is it for making urine in the nephron! But whoah wait, I’m not done yet! There are still some more to come on the urinary system but since I don’t want to bore you to death, I will finish up on the urinary system on my next post. Not sure when my next post will be since tomorrow is the last day of lectures for me before I will be taking 5days off for the Easter holidays! But I hope you learnt something new from this post and Happy Easter!!🐰🐰

xx

Our Body’s Built-In Filter!

Hello, again internet world!

To start off my revisions for Biology & Human Biology and Organic Chemistry, I will start with revising the information that has been stored in my brain most recently, which would be the Urinary System.

Source: Pinterest

I never knew much about the urinary system or how the kidney’s make urine so the past 2 weeks of lectures on the urinary system were all very new to me. And if I’m being honest here, I am quite unsure of what the kidneys are called in Korean (I’m Korean-American so I should know this🙈). But oh well,  I’ll learn it someday!

So, time to get crackin’ with my hair tied up,  some Jazz playing in the background, windows open for fresh air, got my big glass water bottle out for hydration, and most importantly I have just got back from the toilet having done a wee! The result of my kidney’s properly functioning!😁 (this is the type appreciation you gain when you learn about the human body lol)

Our urinary system has it’s main organ which are the Kidneys; kind of like the principle dancer in a ballet so to say. The main attraction who does the most dancing and gets most of the attention/credit. The rest of the organs are the Ureters, Bladder, and Urethra; in this case the corpse de ballet in a ballet. They don’t have as much of a big role, they’re not as appreciated as the principle dancer, but the ballet certainly would not be complete or functional without the corpse de ballet. And no, the ureter and the urethra are not the same (I didn’t know that either).

So what do these organs do? Since the kidneys have the biggest role in the urinary system, let’s start with the kidneys.

The kidneys are two fist-sized, bean-shaped organs that are near where your lowest ribs are. They also always have a friend, the adrenal glands (will explain this in the future) sitting on top of them. The kidneys have 3 layers of supportive tissue to protect, encase, and anchor them to their surrounding area. These layers are called the fibrous capsule, perineal fat capsule, and the renal fascia.

Source: Unknown

This diagram here is an illustration of the kidney anatomy, also called renal anatomy. You will start to notice that anything “renal” is related to the kidneys. There are about 8 lobes in each kidney, each compromised of the cortex, medulla, renal columns, calyces, and pelvis (no, not the pelvic bone).

As you can see, the cortex is in the outer region of the kidney and it is where ultrafiltration (filtration of blood to urine) occurs. The medulla is located more inwards than the cortex, and it makes up the renal pyramids as you can see in the diagram. The renal pyramids are made up of tons of nephrons (we’ll get to this) which is responsible for the main filtering job of our blood. Calyces are the tubes that collect freshly made urine from the pyramids and the funnel-shaped renal pelvis then sends the urine to the ureter which then eventually collects in our bladder.

Going back to the main organs in the urinary system, the ureters are the tubes connecting the kidneys to the bladder. But fun fact, urine doesn’t just go down through the ureter to the bladder because of gravity, it moves down through a movement called peristalsis which is movement caused from smooth muscles surrounding the ureter that kind of massages the urine down to the bladder in a wave-like contracting movement. It also has valve like folds to prevent urine from backflowing up to the kidneys.

Once the urine goes down the ureter through peristaltic movement, it is collected in the bladder until it is excreted from the body through the urethra. The urethra once again pushes urine out of the body through peristaltic movement.

So this is the very basics of the urinary system. Since the urinary system is very complicated with so much information, I will continue with how filtration happens in the next post.

If you are revising for an exam like me or have just read this from curiosity, either way, I hope this post wasn’t boring and that it was easy to understand my use of words.

Till next time!

xx