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.
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!
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!