Urinary system Flashcards
Organs of urinary system
-right and left kidney
-right and left ureters
-urinary bladder
-urethra
Kidney structure
-cortex= outer region
-medulla= inner
-renal artery and renal vein
-major and minor calyxes that flow down into ureter
Nephron structure
-afferent arteriole leads into glomerulus
-efferent arteriole leads out the glomerulus
-then into proximal convoluted tubule and loop of Henle
-then into distal convoluted tubule
-into collecting duct
-loop of Henle surrounded by vasa recta (blood vessels)
Function of nephron
Primary
-balance plasma, toxins
-filtration
-reabsorption
-secretion
Secondary
-control BP
-produce RBCs
-absorb Ca
Glomerulus
-high pressure capillary bed between afferent and efferent arterioles
-surrounded by bowman’s capsule
-podocytes extend to cover glomerular capillaries
Glomerulus filtration membrane
-pores in glomerular endothelial wall
-prevent RBCs from passing through but other components of blood can fit through
-basal lamina prevents filtration of larger proteins
-slit membrane prevents filtration of medium size proteins
Bladder structure
-ureters lead into bladder
-walls made of detrusor muscle which allows bladder to stretch
-detrusor muscle cells are pear shaped
Specific kidney functions
-regulate ions in blood eg. Na+ k+ Ca2+ Cl-
-regulate blood pH- excrete H+ and retain HCO3-
-regulate blood vol- conserving or excreting water and Na+
-regulate BP- secretes renin which activate angiotensin aldosterone pathway which causes vasoconstriction
-regulate blood glucose via gluconeogenesis
Glomerular filtration
-blood enters glomerular knot via afferent arteriole
-glomerular knot has a high hydrostatic pressure, causing ultrafiltration
-all that is filtered out of the blood enters the bowman’s capsule and into proximal convoluted tubule
-blood then leaves glomerulus via efferent arteriole
Pressures in glomerulus
Glomerular blood hydrostatic pressure:
-blood pressure in glomerular capillaries
-promotes filtration by forcing water and solutes into blood plasma
Capsular hydrostatic pressure:
-opposes filtration
-comes from fluid already in bowman’s capsule
Blood colloid osmotic pressure:
-opposes filtration
-occurs due to proteins, albumin, globulins, fibrinogen in the blood
Juxtaglomerular apparatus
-outside Bowman’s capsule and glomerulus
-partly formed by wall of distal convoluted tubule forming macula densa (part of the JGA)
-composition of fluids controlled by cuboid epithelial cells
Juxtaglomerular cells (afferent arteriole)
-smooth muscle cells line afferent arteriole
-if osmolarity of filtrate too high JG cells contract
-this decreases glomerular filtration rate
-if osmolarity too low JG cells dilate
Macula densa cells
-regulate renin from JG cells
-renin converts angiotensinogen to angiotensin 1
-A1 not active until converted to A2
-A2 is a systemic vasoconstrictor that regulates BP
Proximal convoluted tubule
-walls formed by cuboid cells with microvilli on surface forming a brush border
-SA maximises absorption of Na+ Cl- and water
-Na+ AT out of cells in wall into blood
-causes Na+ to enter the cells
-decreases WP inside wall, so water moves in via osmosis
-Na+, Cl-, glucose reabsorbed into blood
Distal convoluted tubule
-formed simple cuboid epithelium
-short than PCT
-fewer microvilli on surface
-mitochondria which pump ions against conc gradient
-fewer mitochondria than PCT
