Physiology Water Balance and Important for Homeostasis

Question :

1. What is water balance and why is it important for homeostasis?

2. Describe how each of the following hormones affects water reabsorption, either directly or indirectly: ADH, angiotensin II, aldosterone, and ANP.

Answer :

Water Balance 

Water balance is a relation between the total amount of water that enters into the body or organism through the process of ingestion liquid as well as food and the total amount of water that is lost from the body through bowels, skin, kidneys, as well as lungs (Armstrong & Johnson, 2018). In simple words, water balance is the relation between the total amount of water that an individual intake and the total amount of water that the individual dispose of in a day. Thus, water balance advocates that the amount of water taken should be equal to the amount of water lost. 

ADH: it promotes reabsorption of water as it acts directly in collecting ducts. In the absence of ADH water flows out as urine because collecting ducts are almost resistant to water.

Angiotensin II: It also increases water reabsorption because it helps the body to retain sodium that changes the way blood is filtered that increases water reabsorption. 

Aldosterone: it forms the renin-angiotensin-aldosterone system. Renin is an enzyme due to which several chemical reactions occur that produce angiotensin II which further stimulates aldosterone. It then increases the reabsorption of water and salt (Walls et al., 2020). 

ANP: It prevents reabsorption of sodium by the renal tubules that reduce water reabsorption.

Alcohol or wine is a diuretic that increases the amount of water lost through urine. It makes the body dehydrated. When the body is dehydrated, the pituitary gland releases a hormone that helps the body to retain more water. Consumption of alcohol prevents the release of this hormone and hence kidney releases more water than normal. It makes the body dehydrated and hence an individual feels thirsty in the morning (Inenaga et al., 2017). It also causes headaches because the potassium concentration of the body reduces. In order to recover, enough amount of water should be taken. Also, the consumption of alcohol should be limited.

References 

Armstrong, L. E., & Johnson, E. C. (2018). Water intake, water balance, and the elusive daily water requirement. Nutrients, 10(12), 1928.

Inenaga, K., Ono, K., Hitomi, S., Kuroki, A., & Ujihara, I. (2017). Thirst sensation and oral dryness following alcohol intake. Japanese Dental Science Review, 53(3), 78-85.

Walls, J. D., Weinstein, M. L., & Atkins, J. H. (2020). Neuroendocrine Physiology: Fundamentals and Common Syndromes. In Essentials of Neurosurgical Anesthesia & Critical Care (pp. 15-24). Springer, Cham.