Question Video: Defining the Term “Homeostasis” | Nagwa Question Video: Defining the Term “Homeostasis” | Nagwa

Question Video: Defining the Term “Homeostasis” Biology • Third Year of Secondary School

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Controlling blood sugar levels is an important part of homeostasis. What is homeostasis?

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Video Transcript

Controlling blood sugar levels is an important part of homeostasis. What is homeostasis? (A) The maintenance of a constant internal environment. (B) The maintenance of a constant external environment. (C) The maintenance of a constant body temperature. (D) The maintenance of a changing external environment.

This question is asking what the word “homeostasis” means in biology. The prefix homeo- is a derivative of the familiar root word “homo” which means same. The suffix -stasis comes from the Greek word that means stoppage or standing, which describes how something in stasis remains still, in a state of equilibrium.

Well, homeostasis does not exactly keep things completely constant, but it does aim to maintain a state of equilibrium within our bodies within a narrow range. For example, when body temperature becomes too high due to sitting out in the Sun for too long, we begin to sweat. This is the body’s way of trying to cool us down and maintain a fairly constant internal temperature so that all of our cellular processes can continue to occur efficiently.

This question provides us with another example of homeostasis: controlling blood sugar levels. In your body, a sugar called glucose can either be stored as glycogen or used to release energy in a process called cellular respiration. Too little glucose, or too much glucose, can be very dangerous for the body. So we, usually unconsciously, closely regulate and maintain its concentration in our bloodstream. The pancreas is an important organ that usually helps to control blood glucose levels.

If glucose levels in the blood are high, such as after a sugary snack, this usually stimulates the pancreas to release a hormone called insulin. Insulin causes more glucose to be stored as glycogen, among its other effects, which reduces blood glucose level back to a healthy range. However, if blood glucose levels become too low, the pancreas releases a different hormone called glucagon. Glucagon can cause glycogen stores to be broken down so that more glucose is released back into the blood, increasing blood glucose back to a healthy range.

If we take a look back at the answer choices, we can see the answer choice (C) is describing an example of homeostasis: maintaining a constant body temperature. However, we know that there are other conditions that the body needs to maintain within a narrow range, such as a blood glucose. So while this is a good example of homeostasis, it is not the definition that the question is asking for.

Homeostasis has nothing to do with maintaining an external environment, as suggested in answer choices (B) and (D). Both of these choices are also therefore incorrect.

Instead, homeostasis involves maintaining a constant internal environment in response to, and in spite of, any external or internal changes. Therefore, the correct answer to this question is that homeostasis is (A), the maintenance of a constant internal environment.

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