Kidneys perform following categories of functions:
- Homeostasis
- Urine Formation
- Hormone Secretion
Homeostasis
Kidney play a critical role to maintain healthy serum, interstitial, and intracellular environments. Here are the some of the homeostatic functions that kidneys perform:
- Acid-base balances (Davenport diagram is a must for medical students to understand.)
- Serum electrolyte concentrations in varying external and internal situations. (Knowing kidney’s role to maintain Na+, K+, Ca++, H+, PO4, NH3, etc. is critical.)
- Total body fluid and its distribution in various compartments is influenced by the kidneys.
- Body fluid osmolarity
Urine Formation
Kidney has a number of functions that help with the homeostasis. One result of this is to excrete extra water, electrolytes, and waste products.
Following renal Processes are used for Homeostasis
- Filtration. Passive movement of the water and electrolytes from the serum into the nephron (glomerular capsule).
- Reabsorption. Active and passive movement of the filtrate back into the interstitium and blood compartment.
- Secretion. Active movement of the substances from the serum to the nephron at any point other than the glomerulus.
- Excretion. discarding the waste products to the bladder and eventually out of the body.
Hormone Secretion
Kidneys make and release following hormones in the blood:
- Vitamin D conversion to its active form.
- Renin secretion helps with blood pressure and blood volume.
- Erythropoietin helps with the RBC concentration (hematocrit).
Hormones Acting on the Kidneys
Following hormones influence kidney’s function:
- Antidiuretic Hormone (ADH).
- Atrial Natriuretic Hormone (ANH).
- Renin-Angiotensin-Aldosterone System.