Question

How blood maintains water balance in the body?
A. By regulating the pH of the body
B. By bringing constant exchange of water between circulating blood and tissue fluid
C. By transporting the excretory material
D. All of the above

Answer 1

Hint: Water is extremely essential for the survival of human beings. To increase the input of water, there is an osmoregulatory mechanism. It is activated in response to changes in water volume in the blood but it is also sensitive to changes in blood osmolality. It has something to do with the sodium cations. The water and salts concentration is equal inside and outside the cells. This is important for body cells to function efficiently.

Complete answer:
All three options given above are important functions that the blood does. However, talking about maintaining water balance, only one option fits in correctly. For regulation of water balance, two important aspects are important to be understood.

There are physiological events that initiate thirst mechanisms. Gastric and pancreatic juices are secreted by the foods we eat. These fluids contain a great amount of water. The body organs exchange around 10 liters of water per day. The osmoregulation of this exchange includes complex communication between kidneys, brain and endocrine system.

There has to be an equal amount of water input and water output. The urge to drink water is due to complex mechanisms of hormones and neuron responses that work in a coordinated manner to increase water input and contribute towards fluid balance in the body.

Hence, the correct answer is option (B).

Note: The kidneys can detect the blood volume. They have some protein sensors that are able to detect blood volume. When low blood volume is detected, the kidney cells detect decreased pressure and secrete renin enzymes. This renin cleaves another protein into a hormone which is called angiotensin. This angiotensin targets different organs like adrenal glands, muscle tissues by the arteries and hypothalamus and can rapidly restore blood volume.