The word homeostasis comes from the Greek words “homoios” which means “same”, and “stasis” which means “steady” or “standing still”.
Homeostasis is the ability to maintain a relatively stable internal environment that persists despite external changes. It refers to the regulation of conditions in the body such as temperature, water content and carbon dioxide levels.
Living organisms from plants to puppies; need to maintain homeostasis constantly to properly grow, work, and survive. In general, homeostasis is essential for normal cell function and overall balance!
The maintenance of body temperature!
Thermoregulation is a process that allows your body to maintain its core internal temperature. All thermoregulation mechanisms are designed to return your body to homeostasis.
This is a state of equilibrium (balance)!
One of the most common examples of homeostasis is the regulation of body temperature.
Maintaining body temperature is super important as the body needs to control and maintain the temperature at which the body’s enzymes work best, which is usually 37°C. Enzymes in our cells help in speedy chemical reactions, with lots of bodily processes, but these enzymes need to be in an optimal temperature to function properly.
To maintain this, the body controls temperature either by producing heat or releasing excess heat. When the body temperature goes beyond 37°C, the person would get a fever and if it drops below this limit, the person would get hypothermia.
Why do we sweat?
We are maintaining our body temperature! Sweating helps release heat, which helps maintain optimal body temperature for our enzymes! As the water in the sweat evaporates, the surface of the skin cools, essentially cooling us down.
Wonder why dogs pant while they’re hot?
Yep, that’s homeostasis!
Once a dog’s body temperature rises, they can’t sweat through their skin like we do to cool off. Dogs can sweat through their paw pads a little bit, but it’s by panting that dogs circulate the necessary air through their bodies to cool them down. Dogs quickly exchange hot air from their lungs with cool external air, which speeds the evaporation of water from their tongue.
What is osmoregulation?
Osmoregulation is the control of water levels and mineral ions (salt) in the blood. Water is essential to life, thus osmoregulation is vital to the health and well-being of humans and other animals.
Water levels and mineral ions in the blood are controlled to keep the concentrations the same inside the cells as around them. The cells are protected by stopping high quantities of water from entering or leaving them by osmosis. If body cells lose or gain too much water, then they do not function efficiently.
If the concentration of water is the same inside and out the cells, they remain in their normal state. If the water concentration is too high outside, water enters the cell by osmosis, and they may burst.
What is negative feedback?
Negative feedback is the body’s mechanism for reversing a change in internal conditions so that it returns to the optimum. Whether this is optimum body temperature, pH or water levels.
The optimum point in the body is being continuously monitored by receptors. When the receptors detect any change away from the optimum, they send signals to a co-ordinator.
The co-ordinator then decides which response is appropriate to this change by sending signals to effectors, which bring about the change that returns the internal conditions to their optimum.
What is positive feedback?
The absolute opposite of negative feedback!
Positive feedback is the opposite of negative feedback; in that, it encourages a process and amplifies the action of a system. Positive feedback is a process that can continue to amplify the body's response to a stimulus until a negative feedback response is ready to take over.
Positive feedback is often a normal way of producing rapid change. Positive feedback can be considered harmful and sometimes even life-threatening due to its ability to change the internal state so rapidly and far from its homeostatic set point. High fever for example is beneficial up to a point, however, if the body temperature rises above 42°C it may create a dangerous positive feedback loop.
And why do I need to know this?
This is a key GCSE Biology topic that pops up in the exam paper each year! To test your knowledge, try writing each of the titles above on the front of a flashcard, and test yourself by memorising and trying to write the definition of the term on the back.
You can keep hold of the flashcards and use them to test yourself throughout the school year.
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