Processes involved in the human kidney Essay

-Blood enters each kidney via renal artery and leaves each kidney via renal vein -Urine exists the kidney through a duct called the ureter and the uruters of both kidneys drain into a common urinary bladder -Kidney consists of outer renal cortex and inner renal medulla -Nephron is functional unit of vertebrate kidney -Consists of single long tubule and ball of capillaries called the glomerulus -Bowman’s capsule surrounds the glomerulus -Kidney regulates the composition of the blood and produce urine -Filtration occurs as blood pressure forces water, urea, salts, and other small solutes from the blood in the glomerulus into the Bowman’s capsule -Nonselective -Filtrate goes into proximal tube, loop of Henle (a hairpin turn with a descending limb and ascending limb) and the distal tubule -Kidney consists of cortical nephrons and juxtamedullary nephrons (only in mammals and birds) -Most of filtrate is reabsorbed back into blood; the kidneys take out about 1% -Proximal and distal tubules are the most common sites of secretion -Very selective process with both passive and active transport of solutes -Proximal, distal tubules, and loop of Henle contribute to Reabsorption -Collecting duct also helps in Reabsorption -Mammalian’s kidney’s ability to conserve water is considered an important adaptation -Antidieretic hormone is important in osmoregulation -Made in hypothalamus and released when osmolarity in blood rises above certain point -ADH acts on the distal tubules and collecting ducts by increasing their permeability to water -Causes more water Reabsorption -Is turned off through negative feedback -Juxtaglomerulur apparatus located in the vicinity of the afferent arteriole, which supplies blood to the glomerulus -When blood pressure or blood volume in the afferent arteriole drops, the enzyme rennin causes chemical reactions that create a peptide called angiotensin II -Angiotensin II increases blood pressure and blood volume by constricting arterioles and decreasing blood flow to many capillaries like the kidney -Causes more salt and water reabsorption to increase blood volume -Causes release of aldosterone, which also acts on nephron’s distal tubules and helps, reabsorb more sodium and water -Negative feedback turns rennin production off -Called the rennin-angiotensin-aldosterone system -Atrial natriuretic factor opposes RAAS -Released by the heart in response to an increase in blood volume and pressure -Inhibits the release of rennin -Inhibits NaCl reabsorption and reduces aldosterone release from adren