IMAT 2012 Q44 [Homeostasis]

Which of the examples of homeostasis do NOT require the brain to be involved in the control process?

  1. temperature regulation
  2. osmoregulation (regulation of the water content of blood)
  3. blood glucose concentration regulation

A. 2 and 3 only
B. 3 only
C. 1 and 2 only
D. 2 only
E. 1 only

The answer to this question is B, only blood glucose concentration does NOT require the brain to be involved in control among the choices given.

To understand the rationale behind this this answer, you must be familiar with what does control the different aspects of homeostasis given in the choices.

Temperature regulation:

  • Thermoregulation is an important process that needs to be controlled in order to ensure optimal functioning of our bodies. Thus, emperature regulation can be summarized in 3 main processes. The signal sensed and sent by our receptors regarding temperature throughout our body, which is then received by the central control (our brain) to be interpreted, which then subsequently sends signals for appropriate responses by our body like shivering and sweating.
  • What is meant by “central control”? The part of our brain that is responsible for thermoregulation is the hypothalamus. The hypothalamus is tasked to recognize the signals it receives regarding temperatures throughout our body, which prompts itself to send signals to the skin, glands, muscles, and even our internal organs. This is to ensure that our internal temperatures are at the range that is sufficient for our cells to perform the vital functions that guarantees our survival. This process allows us to adapt to various external temperatures without much adverse effects.
  • Therefore, since this aspect of homeostasis is controlled by the hypothalamus, which is a part of the brain, this choice is not the correct answer.

Osmoregulation (Regulation of water content in the blood):

  • If osmoregulation can be summarized in one sentence, it would be our body’s task to balance water and solutes to provide the optimum environment for our tissues and organs to function. Let us then trace how osmoregulation works in our body. Water concentration is sensed by the osmoreceptors in our hypothalamus. The hypothalamus is then prompted to induce the pituitary gland, and whether or not the body needs to retain or excrete water, the pituitary gland will either increase or decrease the secretion of the hormone ADH, respectively. ADH then acts on our kidneys, which is then tasked to retain water for return back to the circulation.
  • Thus, like thermoregulation, since this aspect of homeostasis is controlled by the hypothalamus, this is not the correct choice.

Blood sugar concentration regulation:

  • If you are wondering why our glucose levels don’t spike up to dangerous levels after we eat, and neither does it drop to critical levels when we are fasting, it is because it is being regulated by an important organ called the pancreas. The role of this organ is to secrete 2 hormones in balance, namely, insulin and glucagon which mediate functions that are in opposition of each other.
  • To be more specific, insulin is secreted in response to hyperglycemia (increased glucose levels in the blood), whereas glucagon is secreted in response to hypoglycemia (low blood glucose). These hormones act on different organs which include the liver and our muscles to aid in the maintenance of the optimum glucose level in our blood, especially since glucose is the main source of energy for our brain.
  • With that being said, it now makes sense why the answer is choice B, since this is the only aspect of homeostasis among the choices that does NOT require the brain for control.