Term
| (04-24) What do mesangial cells do? |
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Definition
| support and regulate blood flow in glomerular capilaries |
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Term
| (04-24) What kidney cell/s have fenestrations? |
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Definition
| Capillary endothelial cells (podocytes have "slit pores") |
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Term
| (04-24) What other type of muscle does a mesangial cell resemble? Why? |
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Definition
| It is reminiscent of smooth muscles; it is capable of contracting. |
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Term
| (04-24) How many layers of what kind of membrane must filtrate pass through? What are the layers' names? |
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Definition
| filtrate must pass trough 3 layers of glomerular membrane: Capillary endothelial cell, basement membrane, epithelial cells |
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Term
| (04-24) How much plasma moves into the filtrate? |
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Definition
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Term
| (04-24) Define glomerular filtration rate (GFR). |
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Definition
| The amount of plasma filtered per unit time |
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Term
| (04-24) From the glomerulus, where does filtrate go? |
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Definition
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Term
| (04-24) We filter more than 6 L of plasma through our body every hour. Why don't we have to pee constantly? |
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Definition
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Term
| (04-24) Define glomerular filtration pressure (GFP). What is used to calculate it? |
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Definition
| GFP is the driving force for filtration. It is the sum of the "Starling forces" |
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Term
| (04-24) What are the factors in GFP that favor movement from blood to filtrate? |
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Definition
| 1) PGC = hydrostatic pressure in the glomerular capillaries (mean arterial pressure matters here); 2) (Pi)BC = Bowman's capsule osmotic pressure |
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Term
| (04-24) How effective is the capsule osmotic pressure in the movement from blood to filtrate? |
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Definition
| It's not. Not really. We can assume the value is zero. |
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Term
| (04-24) What are the factors of glomerular filtration pressure that influence movement from filtrate back to blood? |
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Definition
| 1) (Pi)GC = the osmotic pressure in glomerular capillaries (affected by protiens like albumin and globulins) 2) PBC = the hydrostatic pressure in Bowman's capsule |
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Term
| (04-24) What is the formula for glomerular filtration pressure? (given on an exam) |
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Definition
| GFP = PGC + (Pi)BC - PBC - (Pi)GC |
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Term
| (04-24) What is the main driving force (factor with the highest value) in glomerlar filtration pressure? |
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Definition
| Hydrostatic pressure in the glomerular capillaries (PGC) |
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Term
| (04-24) GFR is CONSTANT/VARIABLE across a range of blood pressures. |
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Definition
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Term
| (04-24) What types of control influence Glomerular filtration rate? |
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Definition
| 1) Local , or intrinsic, control 2) Zone of autoregulation. |
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Term
| (04-24) Define zone of autoreglation. |
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Definition
| An area on a GFR graph between ~70 and ~180 that keeps GFR constant. |
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Term
| (04-24) what are the three mechanisms of inrinsic control within the zone of autoregulation? |
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Definition
| 1) Myogenic regulation (smooth muscle of the afferent arteriole) 2) Tubuloglomerular feedback (macula densa senses fluid flow and contracts afferent arteriole) 3) Mesangial cell contraction (contract in response to stretching) |
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Term
| (04-24) In myogenic regulation of GFR, what are the physical changes made when there is an increase in pressure? |
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Definition
| the afferent arteriole contracts, increasing resistance and decreasing glomerular filtration rate |
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Term
| (04-24) What physiological structures does tubuloglomerular feedback affect? |
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Definition
| cells of the macula densa in the distal tubule |
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Term
| (04-24) In tubuloglomerular feedback, what reacts to an increase in fluid flow? |
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Definition
| The macula densa cells sense increases in fluid flow in the distal tubule. An increase in flow leads to a contraction of the afferent arteriole and a decrease in Glomerular Filtration Rate. |
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Term
| (04-24) What do mesangial cells do to help keep GFR lower? |
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Definition
| An increases blood presure sretches mesangial cells, which contract. This leads to decreased filtration surface and a decrease in glomerular filtration rate. |
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Term
| (04-24) Outside the zone of autoregulation, how is GFR controlled? What is the control dependent on? |
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Definition
| Extrinsic control of GFR (You can think of this as "non-local"). It has to do with the baroreceptor reflex. |
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Term
| (04-24) What's the formula for mean arterial pressure? |
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Definition
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Term
| (04-24) What does the extrinsic control of GFR do when it senses a large amount of blood loss? |
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Definition
| It increases cardiac output and total periferal resistance, lowering GFR |
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Term
| (04-24) Define filtered load. What is its one caveat? |
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Definition
| How much of a particular solute is filtered per unit. Caveat: the solute must freely cross the glomerular membrane |
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Term
| (04-24) What is the formula for the filtered load (FL)? |
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Definition
| FL = (glomerular filtration rate) ([concentration X in plasma]) |
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Term
| (04-24) If you have a filtered load of 125 mL/min, and you're measuring glucose at 1 mg/mL, what is the FL of glucose? |
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Definition
| FL of glucose = (125 mL/min) (1 mg/mL) = 125 mg/min |
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Term
| (04-24) Define clearance, in terms of GFR |
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Definition
| The volume of plasma cleared of a substance per unit time |
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Term
| (04-24) What is the volume for clearance? |
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Definition
| Clearance = ((concentration of X in urine)(rate of urine production))/(concentration of X in plasma) AKA Cx = (([X]urine])(dU/dt))/([X]plasma) |
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Term
| (04-24) Why is the clearance of glucose zero -- even when the filtered load of glucose is greater than zero? |
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Definition
| Clearance indicates a volume of plasma that is completely cleared of a substace. Glucose is freely filtered and completely reabsorbed, so the concentration of [glucose]urine will always be 0 (in the numerator on the clearance formula |
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Term
| (04-24) What is the rule about clearance about a freely filtered, not secreted nor reabsorbed substance? |
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Definition
| If a substance x is freely filtered and is not secreted or reabsorbed, then clearance of that substance equals GFR |
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