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10 Cards in this Set
- Front
- Back
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What layers must be passed to get filtered to the Bowman's capsule? |
Glomerulus capillary (lumen) -epithelial cell (pores) Basement membrane (basal lamina) Inner layer of Bowman's capsule (lumen) -filtration slits between the foot processes of the podocytes in the inner layer of Bowman's capsule |
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What does filtration depend on? |
Molecular size -no hindrance to movement of molecules less than 700d -small ions, glucose, urea, amino acids, and many hormones -Filtration barrier excludes plasma albumin (66kd): filtrate is protein-free Electrical charge -negatively charged macromolecules are filtered to a lesser extent, and positively charged molecules are filtered to a greater extent -polyanions repel negatively charged macromolecules during filtration |
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What are the 3 physical forces involved in glomerular filtration? |
Glomerular capillary blood pressure Plasma-colloid osmotic pressure (COP) Bowman's capsule hydrostatic pressure |
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Explain how the physical forces affect glomerular filtration. |
Glomerular capillary blood pressure: favours filtration (55) Plasma-colloid osmotic pressure: opposes filtration (30) Bowman's capsule hydrostatic pressure: opposes filtration (15) Net filtration pressure: favours filtration (10) |
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Explain glomerular capillary blood pressure. |
Pressure depends on -contraction of the heart -resistance to blood flow by afferent and efferent arterioles Afferent end: 60 mmHg Efferent end: 58 mmHg |
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Explain plasma-colloid osmotic pressure. |
-caused by unequal distribution of plasma protein Afferent end: 21 mmHg Efferent end: 33 mmHg |
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Explain bowman's capsule hydrostatic pressure. |
-opposes filtration -15 mmHg |
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Explain net filtration pressure. |
-Afferent end: 60 -(21 + 15) = 24 mmHg -Efferent end: 58 -(33 + 15) = 10 mmHg |
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What does glomerular filtration depend on? |
Net filtration pressure, surface area, permeability of the glomerular membrane |
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How is the GFR controlled? |
-autoregulation (local control) -myogenic mechanism -tubuloglomerular feedback (TGF) -extrinsic sympathetic control (aimed at long-term regulation of blood pressure); Global control -SNS input to afferent arterioles -baroreceptor reflex |
