Function of the Kidney
The kidneys excrete a variety of waste products produced by metabolism into the urine. The microscopic structural and functional unit of the kidney is the nephron. It processes the blood supplied to it via filtration, reabsorption, secretion and excretion; the consequence of those processes is the production of urine. These include the nitrogenous wastes urea, from protein catabolism, and uric acid, from nucleic acid metabolism.
The ability of mammals and some birds to concentrate wastes into a volume of urine much smaller than the volume of blood from which the wastes were extracted is dependent on an elaborate countercurrent multiplication mechanism.
This requires several independent nephron characteristics to operate: a tight hairpin configuration of the tubules, water and ion permeability in the descending limb of the loop, water impermeability in the ascending loop, and active ion transport out of most of the ascending limb. In addition, passive countercurrent exchange by the vessels carrying the blood supply to the nephron is essential for enabling this function.
The kidney participates in whole-body homeostasis, regulating acid–base balance, electrolyte concentrations, extracellular fluid volume, and blood pressure. The kidney accomplishes these homeostatic functions both independently and in concert with other organs, particularly those of the endocrine system.
What Happens If My Kidneys Fail Completely?
Complete and irreversible kidney failure is sometimes called end-stage renal disease, or ESRD. If your kidneys stop working completely, your body fills with extra water and waste products. This condition is called uremia. Your hands or feet may swell. You will feel tired and weak because your body needs clean blood to function properly.
Untreated uremia may lead to seizures or coma and will ultimately result in death. If your kidneys stop working completely, you will need to undergo dialysis or kidney transplant.
Points to Remember
- Your kidneys are vital organs that keep your blood clean and chemically balanced.
- The progression of kidney disease can be slowed, but it cannot always be reversed.
- End-stage renal disease (ESRD) is the total loss of kidney function.
- Dialysis and transplantation can extend the lives of people with ESRD.
- Diabetes and high blood pressure are the two leading causes of kidney failure.
- You should see a nephrologist regularly if you have renal disease.
- Chronic kidney disease (CKD) increases the risk of heart attacks and strokes.
- If you are in the early stages of renal disease, you may be able to save your remaining renal function for many years by:
- Controlling your blood glucose
- Controlling your blood pressure
- Following a low-protein diet
- Maintaining healthy levels of cholesterol in your blood
- Taking an ACE inhibitor or an ARB
- Quitting smoking