KIDNEYS: WHAT ARE THEY?
The kidneys are a pair of bean-shaped organs located at the posterior wall of the abdomen. Each kidney measures about 11 cm long, 6 cm wide and 3 cm thick and weighs about 160 g.
The kidney is made up of approximately one million functioning units called nephrons. Each nephron consists of a glomerulus and tubules. The tubule is a tube like structure. The glomerulus is a network of tiny blood vessels surrounded by a cup-shaped structure called the glomerular (Bowman's) capsule.
The glomerulus serves as a filter. The filtrate then drains into the tubule. The concentration of the filtrate is altered along the length of the tubule by various processes to form urine which leads into the collecting duct. Urine is then drained into a common funnel-shaped sac called the renal pelvis. The ureter connects the renal pelvis to the bladder from each kidney. Urine formed by the kidneys, flows through the ureters into the bladder where it is passed out through the urethra.
FUNCTIONS OF THE KIDNEY
Each day the two kidneys excrete about 1.5 to 2.5 litres of urine. In doing this, the vital functions of the kidney is to remove toxic and waste products and excess water from the body. The other functions of the kidney are to maintain the body's balance of various salts such as sodium, potassium, calcium, phosphate as well as acid substances.
Normal kidneys release several hormones, three of which are renin, erythropoietin and activated form of Vitamin D. Renin helps to regulate blood pressure. Erythropoietin is responsible for stimulating the production of red blood cells in the bone marrow. Activated Vitamin D helps to maintain normal bone structure.