2.  Water level balancing  Red blood cell regulation  Acid regulation  Osmolality regulation

3. Excretory Functions : The kidneys filter out toxins, excess salts, and urea, a nitrogen- based waste created by cell metabolism. Urea is synthesized in the liver and transported through the blood to the kidneys for removal. This is done by formation and excretion of urine.

4. RED BLOOD CELL REGULATION Erythropoietin is released in response to hypoxia(low levels of oxygen at tissue level) in the renal circulation. It stimulates erythropoiesis(production of red blood cells) in the bone marrow ACID REGULATION : As cells metabolize, they produce acids. Foods we eat can either increase the acid in our body or neutralize it. If the body is to function properly, it needs to keep a healthy balance of these chemicals. The kidneys do that, tooReabsorption of vital nutrients

5. Osmolality regulation Any significant rise in plasma osmolality is detected by the hypothalamus, which communicates directly with the posterior pituitary gland. An increase in osmolality causes the gland to secrete antidiuretic hormone (ADH), resulting in water reabsorption by the kidney and an increase in urine concentration. RENAL BLOOD SUPPLY kidneys receive blood from the renal arteries,branch directly from the abdominal aorta. and returns blood to the ascending vena cava the kidneys receive approximately 20% of the cardiac output. Each renal artery branches into segmental arteries, dividing further into interlobar arteries which penetrate the renal capsule and extend through the renal columns between the renal pyramids. The interlobar arteries then supply blood to the arcuate arteries that run through the boundary of the cortex and the medulla. Each arcuate artery supplies several Interlobular arteries that feed into the afferent arterioles that supply the glomeruli.

6. ARTERIES(D0WN) VEINS(UP) Abdominal aortaVena cava Renal artery)Renal vein Segmental arteries - Lobar arteries - Interlobar arteryInterlobar vein Arcuate arteriesArcuate vein Interlobular arteryInterlobular vein Afferent arteriolesEfferent arterioles Glomerulus RENAL PLEXUS OF NERVES: The renal plexus is formed by filaments from the celiac ganglia and plexus, aorticorenal ganglia, lower thoracic splanchnic nerves and first lumbar splanchnic nerve and aortic plexus. It enters the kidneys on arterial branches to supply the vessels, Renal glomerulus, and tubules with branches to the ureteric plexus Some filaments are distributed to the spermatic plexus and, on the right side, to the inferior vena cava. Lymphatic Drainage of the Kidneys is to the lumbar nodes.

11. RENAL BLOOD FLOW AND ITS MEASUREMENT: Renal blood flow (RBF): This is the volume of blood delivered to the kidneys per unit time.kidneys receive roughly 22% of cardiac output, 1.1 L/min in a 70-kg adult male. RBF is closely related to(RPF) Renal plasma flow (RPF): This is the volume of blood plasma delivered to the kidneys per unit time. Renal blood flow (RBF) can be calculated from a patient's RPF and hematocrit using the following equation :