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30 Cards in this Set
- Front
- Back
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Glomerular blood hydrostatic pressure
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Pressure that promotes filtration by forcing water and solutes through the membrane
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Blood colloid osmotic pressure
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Opposes filtration through the presence of proteins in blood plasma
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Capsular hydrostatic pressure
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Opposes filtration by pressure being exerted on membrane from fluid already in the capsular space and renal tube
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Proteinuria
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Protein in urine from kidney
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Hematuria
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Blood in urine lost from kidney
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Edema
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Abnormally high volume of interstitial fluid due to loss of plasma proteins
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Glomerular filtration rate
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amount of filtrate formed in both kidneys each minute
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How is GFR regulated?
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Constricting and dilating afferent and efferent arteries
Altering glomerular capillary surface area available for filtering |
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How do the kidneys autoregulate?
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Autoregulation
Myogenic mechanism Tubulo-glomerular feedback Neural regulation Hormonal regulation Angiotensin II ANP |
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Myogenic regulation (GFR)
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Stretching triggers contraction of smooth muscle cells in walls of afferent arteriole
i. Blood pressure rises → Smooth muscle fibers contract → Blood flow decrease → GFR decrease. ii. Normalizes renal blood flow and GFR within seconds after change in blood pressure |
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Tubulo-glomerular feedback (GFR)
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Macula densa provides feedback to glomerulus
High GFR → Increased delivery of Na+, Cl-, and water → Macula densa inhibits release of nitric oxide in juxtaglomerular apparatus → afferent arterioles constrict → Less blood flow into glomerular capillaries → Lower GFR |
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Neural GFR regulation
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NE is released by ANS
a. Afferent and efferent arterioles are both constricted to similar distance. b. Causes vasoconstriction and GFR drops through the lowering of blood flow. |
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Angiotensin II
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Vasoconstrictor that narrows afferent and efferent arterioles (reduces renal blood flow) and decreases GFR
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ANP
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An increase in blood volume (stretching of atria) stimulates the secretion
It increases capillary surface are to promote filtration which raises GFR |
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Route of reabsorption
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Tubule
Interstitial fluid Capillary Blood stream |
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Paracellular reabsorption
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Fluid moves between cells in a passive process
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Transcellular reabsorption
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A substance passes from the fluid in the tubular lumen through the apical membrane of a tubule cell → Cytosol → ISF through the basolateral membrane; K+ is pumped in while Na+ is pumped out.
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Obligatory water reabsorption
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Water follows solutes and is reabsorbed (obligated to)
Occurs in PCT and descending loop of Henle |
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Facultative water reabsorption
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Regulated by diuretic hormones (ADH)
Mainly in collecting duct |
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Where does the maximal amount of reabsorption occur?
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PCT
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Types of transporters in PCT
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Na symporter: 2 Na + 1 glucose pumped in
Na/H antiporter: Na reabsorbed into blood and H secreted into tubular fluid |
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Where does water reabsorption occur in the loop of Henle?
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descending limb (ascending limb not permeable to water)
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Transporters in ascending loop of Henle
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NKCC: Na/Cl active in, K = leaky channels out
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Types of transporters in distal convoluted tubule?
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Na/Cl symporters cause reabsorption
Parathyroid hormone also stimulates Ca reabsorption |
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Cells of collecting duct
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Principal cells: reabsorb Na, secrete K
Intercalated cells: reabsorb K and bicarbonate, secrete H |
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RAA system
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Juxtaglomerular cells secrete renin-> renin clips angiotensin 1 from angiotensinogen-> angiotensin 1+ACE -> angiotensin II -> (decreases GFR by vasoconstriction of afferent arteriole) -> adrenal cortex releases aldosterone -> Principal cells of collecting duct reabsorb more Na and Cl and secrete K, which raises blood volume
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ADH
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Increases water permeability of principal cells in DCT and collecting duct
Stimulates insertion of aquaporin II overall result is more concentrated urine, increased BV and BP |
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ANP
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Occurs due to a large increase in blood volume
• It can inhibit reabsorption of Na+ and water in the PCT and collecting duct. • Also suppresses the secretion of aldosterone and ADH → increase the excretion of urine and Na+ in urine (GFR)→ decreased blood volume and pressure |
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Functions of urinary system
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Regulates blood pressure and blood volume
Regulates blood pH Excretes wastes Regulates blood ions Maintains blood osmolarity Regulates blood glucose level |
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Layers of filtration membrane
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1 Fenestrations allow solutes through (no RBC or platelets)
2 Mesangial cells = contractile 3 Basal lamina prevents larger proteins 4 Filtration slits allow extremely small molecules |
