Download Functional anatomy of the kidney

Renal physiology
1. Function of kidney
2. Functional anatomy of the kidney.
Function of kidney:
1. Excretion of metabolic waste products: The kidney eliminate
waste product of metabolism, that are not needed by the body. These
products include urea (from the metabolism of amino acids),
creatinine (from muscle creatine), uric acid (from nucleic acids),
bilirubin (from hemoglobin breakdown and metabolite of various
hormone). The kidneys eliminate most toxins and other substances
such as drugs.
2. Regulation of water and electrolyte balances: The capacity of the
kidneys to alter sodium excretion in response to change in sodium
intake is 10 fold than normal. This also true for water and other
electrolytes such as potassium, calcium and hydrogen.
3. Regulation arterial pressure: In increase the blood pressure, the
kidney was excreting variable amount of sodium and water and this
lead to decrease blood volume and restore the normal blood pressure.
While in case of decrease the blood pressure the kidney was secrete
vasoactive factors such as renin, that lead to formation of vasoactive
products such as angiotensin II and this lead to vasoconcentriction and
increase the blood pressure.
4. Regulation acid-base balance: By excreting acid and by regulation
the body fluid buffer stores. Kidneys eliminate certain types of acid
such as sulfuric acid and phosphoric acid by metabolism of proteins.
5. Regulation of erythrocytes production: the kidneys secrete
erythropoietin which stimulates the production of red blood cells, one
important stimulus for erythropoietin secretion is hypoxia. So that the
people with severe kidney disease, severe anemia develops as result of
decreased erythropoietin production.
6. Regulation of 1,25-Dihydroxy vitamin D3 production: The
kidneys produce the active form of D3 (1,25-Dihydroxy vitamin D3)
calcitriol, which is essential for normal calcium deposition in bone
and calcium reabsorption by gastro-intestinal tract. It play role in
calcium and phosphate regulation.
7. Glucose synthesis: the kidneys synthesis glucose from amino acid
during prolonged fasting (gluconeogenesis).
Functional anatomy of the kidney
General organization of the kidney and urinary tract: Two kidneys lie
on the posterior wall of the abdomen, outside the peritoneal cavity. Each
kidney of adult human weight about 150 grams. Through hilum pass the
renal artery, vein, lymphatic, nerve supply and ureter that carries the urine
from the kidney to the bladder where it is stored urine until it is emptied
by micturition. Kidney contain outer cortex and inner medulla. The
medulla is divided into multiple cone shaped masses of tissue called renal
pyramids, terminate into renal pelvis.
Renal blood flow:
Blood flow to the two kidneys is normally about 22% of COP (1100 ml/
minute).
Renal artery is a branch of abdominal aorta enter the kidney through the
hilum, then branching to give rise the renal segmental arteries, this
divided to interlobar arteries, divided to arcuate arteries, and this
branched to give an interlobular arteries, to enter the glomerulus as an
afferent arterioles to forming a glomerulus capillary bed and exit as
efferent arterioles then peritubular capillaries, interlobular veins, arcuate
veins, interlobar veins, this veins drain in renal veins and this drain in to
the inferior vena cava.
Nerve supply:
The kidney has a rich adrenergic sympathetic nerve supply distributed to
the:
1. Vascular smooth muscle to cause vasoconstriction.
2. Juxtaglomerular cells to cause renin secretion.
3. Tubular cells to stimulate Na and water reabsorption.