Term
| The descending limb of the loop of Henle is highly permeable to __________, but not to __________. |
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Definition
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Term
| In the juxtaglomerular apparatus, what cells monitor and respond to changes in the osmolarity (or electrolyte concentration) of the filtrate in the tubules? |
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Definition
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Term
| The late distal tubule and cortical collecting duct contain two functional types of cells. Which cells change their permeability in response to hormones? |
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Definition
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Term
| The thick ascending limb of the loop of Henle is highly permeable to ____________, but not to ____________. |
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Definition
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Term
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Definition
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Term
| How much blood is filtered through the kidneys daily? |
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Definition
| About 180L/d, the body only has about 3L |
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Term
| Severe changes in MAP affect which of the Starling forces? |
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Definition
Hydrostatic pressure of the glomerular capillaries (Pgc)
(Pgc is not affected much by changes in MAP from 80-180mmHg because of intrinsic regulatory mechs, but severe hypertension or low blood volume causes more drastic changes) |
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Term
| What intrinsic control mechanisms allow for urine output to remain normal with relatively slight changes in MAP? |
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Definition
| Myogenic regulation (arteriole reacts to stretch) and tubuloglomerular feedback (macula densa secrete paracrine) |
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Term
| Which two Starling forces favor GFR? |
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Definition
| Hydrostatic pressure of the glomerular capillaries (Pgc) and osmotic pressure of the Bowman's capsule (πbc) |
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Term
| Which two Starling forces oppose GFR? |
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Definition
| Hydrostatic pressure of the Bowman's capsule (Pbc) and osmotic pressure of the glomerular capillaries (πgc) |
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Term
| Most filtered fluid is (reabsorbed/excreted). |
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Definition
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Term
| What happens to GFR in extreme cases of hypertension (MAP > 180mmHg)? |
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Definition
| GFR increases. The body interprets this as "helping" by increasing flow rate to decrease plasma volume. |
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Term
| What is myogenic regulation and where does it take place? |
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Definition
A rise in MAP causes the afferent arteriole to constrict in response to stretching, increasing resistance to blood flow. This decreases pressure in vessels downstream and counteracts (but does not change) the initial rise in pressure.
(Same for opposite stimulus) |
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Term
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Definition
| GFP = (Pgc + πbc) - (Pbc + πgc) |
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Term
Increased flow through distal tubule =
(increased/decreased) paracrine secretion from _________ cells =
(constriction/dilation) of afferent arteriole. |
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Definition
increased
macula densa
constriction |
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Term
| Because we filter so much blood every day, small deviations in _____ can result in huge deviations in ionic composition and volume of plasma, interstitial fliud, and ICF. |
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Definition
| GFR (this is why intrinsic control mechanisms - myogenic regulation and tubuluglomerular feedback - are important) |
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Term
| What is tubuluglomerular feedback? |
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Definition
| An intrinsic control mechanism that regulates GFR. A change in GFR causes a change in flow of tubular fluid past macula densa cells, which secrete paracrines to relax or contract the afferent arteriole |
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Term
| When is extrinsic control of GFR necessary and what system is responsible for extrinsic control? |
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Definition
When 80mmHg < MAP > 180mmHG and intrinsic control mechanisms can't keep up
Nervous system |
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Term
| Hemorrhage and excessive sweating are examples of stimuli that would cause a (rise/fall) in MAP. Which mechanism would kick in? |
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Definition
fall
Extrinsic control (SNS) |
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Term
| The juxttaglomerular apparatus involves contact between the _____ and _______. |
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Definition
| distal tbubule and afferent arteriole |
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Term
| An increase in renal sympathetic nervous activity causes vaso_______ of afferent and efferent arterioles which (increases/decreases) renal vascular resistance and (increases/decreases) GFR |
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Definition
constriction
increase
decrease
(We're losing blood! Constrict everything! - Decreases urine output and fluid loss) |
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Term
| Whar are the two barries to reabsorption and secretion? |
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Definition
| Renal tubule wall (more significant) and capillary wall (less significant) |
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Term
| Reabsorption refers to movement of _______ and ________ from the lumen of the _________ into the ______. |
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Definition
filtered solutes and water
tubules
plasma |
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Term
| What percent of filtered sodium is reabsorbed? |
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Definition
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Term
| Reabsorption of most solutes occurs in the ___________. |
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Definition
| proximal and distal convoluted tubules |
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Term
| What is the peritubular space? |
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Definition
| The space between the epithelium of the renal tubules and the peritubular capillaries. |
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Term
| The plasma membrane of the epithelial cells facing the tubule lumen is called the _____ membrance and has _______. |
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Definition
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Term
| What type of junctions are between the epithelial cells of renal tubules? |
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Definition
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Term
| What is the difference between primary ad secondary active transport? |
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Definition
| Primary active transport gets energy directly from ATP whereas secondary follows an electrochemical gradient created at the expense of ATP. |
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Term
| Transporter proteins for substance X are located on the apical membrane of the renal tubule epithelial cells. X is transported (passively/actively) out of the epithelial cells. |
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Definition
| Passively - facilitated diffusion. (Overall mechanism is secondary active transport - actively transported into cell using ATP and transport proteins, then passively transported out via carrier proteins by electrochemical gradient established) |
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Term
| Water reabsorption (from renal tubule to capillaries) follows ______ ________ __ ______. |
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Definition
| active reabsorption of solutes |
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Term
| If a solute can permeate the plasma membranes of the tubule epithelium and capillary epithelium, AND is in higher concentration in the tubular fluid than plasma, how will it diffuse? |
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Definition
| It will diffuse passively into the plasma and follow water reabsorption |
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Term
| For solutes that get reabsorbed 100% (such as urine), what happens when transport maximum is reached? |
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Definition
| Some of the solute will "spill over" into the urine. |
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Term
| How is glucose transported across the apical membrane and into the epithelial cell of the renal tubule? |
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Definition
| Actively cotransported with sodium |
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Term
| How is glucose transported across the basolateral membrane? |
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Definition
| Facilitated diffusion via carrier protein (secondary active transport b/c a high concentration inside cell was previously established by active transport of glucose at apical membrane) |
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Term
| How does tubular epithelium differ along the renal tubule? (3 main ways) |
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Definition
microvilli on the apical membrane
tight junctions
number of mitochondria |
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Term
| Proximal tubule reabsorption is (regulated/nonregulated) |
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Definition
nonregulated
MASS REABSORPTION!!! |
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Term
| 70% of sodium and water reabsorbed from which portion of the renal tubule? |
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Definition
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Term
| 100% of glucose is reabsorbed from which portion of the renal tubule? |
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Definition
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Term
DISTAL TUBULE AND COLLECTING DUCT
(small&few / large&more) microvilli
(less / more) mitochondria
(tight / loose) tight junctions |
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Definition
small & few microvilli
less mitochondria
"tight" tight junctions |
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Term
Hormone receptors are located in the
- distal tubule and collecting duct?
- proximal tubule? |
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Definition
| distal tubule and collecting duct (ADH, aldosterone, etc) |
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Term
| Glucose secretion can cause an (increase/decrease) in urine output) |
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Definition
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Term
Loop of Henle is located in
- juxtamedullary nephrons
- cortical neprons
- both |
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Definition
| both, but the loop of Henle in cortical nephrons only dips a little bit into the medulla, so it is less important for osmotic gradient/water conservation |
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Term
| Material that enters the renal tubule and is not reabsorbed is eventually ______. |
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Definition
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Term
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Definition
| elimation of solute and water in the form of urine |
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Term
| What are two ways substances can enter the renal tubule? |
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Definition
| Filtration through glomerular capillaries or secretion from plasma |
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Term
| 5 main things kidneys regulate |
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Definition
Plasma ionic composition
Plasma volume
Plasma osmolarity
Plasma pH
Removal of wastes/toxins from plasma |
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Term
Filtrate in the Bowman's capsule SHOULD be protein free. An excess of protein can cause forced filtration of protein into the renal tubule. Which Starling force would this contribute to?
Would this favor or oppose filtration? |
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Definition
| It would increase the osmotic pressure of the Bowman's capsule (πbc), which favors filtration |
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Term
| In periods of extreme stress, the sympathetic nervous system will override autoregulation and cause vasoconstriction of blood vessels. What happens to GFR? |
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Definition
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Term
| Kidneys represent about __% of body weight and receive about __% of cardiac output at rest |
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Definition
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Term
| The active transport of what ion is responsible for reabsorption of most substances in the nephron? |
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Definition
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Term
| What happens to the osmolarity of the filtrate as it moves up the ascending limb of the loop of Henle? |
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Definition
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