Kidneys

Description of the kidneys:

•Reddish brown, bean-shaped organs with smooth surface

•About 12 cm long, 6 cm wide, and 3 cm thick in adult

Location of the kidneys:

•Lie on both sides of vertebral column, in depression on the posterior abdominal wall

•Left kidney is 1.5 to 2 cm higher than right kidney, due to position of liver

•The kidneys are retroperitoneal: behind/outside of the parietal peritoneum

•Surrounded by fibrous renal capsule, adipose tissue (renal fat), and connective tissue (renal fascia)

Functions of the Kidneys

The kidneys regulate the volume and composition of body fluids

1.Remove excess water/electrolytes and metabolic wastes from the blood

2.Excrete wastes in the urine

•When kidneys are not functioning properly, hemodialysis and continuous peritoneal dialysis can be used to filter wastes out of the blood

3.Secrete the hormone erythropoietin, which stimulates red blood cell production

4.Secrete enzyme renin, which helps to increase blood pressure

5.Produce active form of Vitamin D (calcitriol), which increases calcium absorption from small intestine when blood calcium level is low