Term
| What do we use PAH to measure? What do we have to remember to do in calculating this? |
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Definition
RPF; add 10% to final value because a small portion cannot be secreted
(90% of PAH is cleared on a single pass – 20% gets filtered and most of the rest gets secreted. 10% gets returned to the body. ) |
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Term
| Is the reabsorption of glucose and amino acids into the peritubular capillaries active or passive? |
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Definition
| Active – it involves sodium-dependent secondary active transporters |
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Term
| If 100% of glucose and amino acids are reabsorbed into the peritubular capillaries, how is this broken up along the nephron? |
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Definition
| 80% in proximal tubule; 20% in distal tubule |
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Term
| What are the units for Tm (transport maximum)? |
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Definition
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Term
| What three loads are plotted on the glucose handling curve? Which are linear until glucose reaches about 200 mg/dl? |
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Definition
Filtration, reabsorption and excretion
F and R are linear until 200 mg/dl |
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Term
| What is the “splay region” on the glucose handling curve? |
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Definition
| The region from 200 mg/dl (RPT) to 375 mg/dl where some glucose is being excreted but some is also being reabsorbed. |
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Term
| What happens at 375 mg/dl on the glucose titration curve? |
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Definition
| ALL of the glucose transporters are saturated |
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Term
| What is the normal plasma glucose concentration on a 12 hour fast? |
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Definition
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Term
| What are most of the proteins that make up the 1.3-1.8 g/day of protein that is filtered? |
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Definition
| Albumin, angiotensin, insulin |
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Term
| How is albumin reabsorbed? |
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Definition
| Pinocytosis in the proximal tubule |
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Term
| How are angiotensin and insulin reabsorbed? |
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Definition
| They are broken up into constituent amino acids and reabsorbed in total |
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Term
| How and where do proteinaceous plugs form? |
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Definition
| They are formed by proteins that filter through damaged glomerular filtration barriers and they form in the hairpin turn of the loop of Henle |
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Term
| What direction of transport do organic anion transporters (OAT) and organic cation transporters (OCT) go in? |
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Definition
| peritubular blood to proximal tubule = secretion |
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Term
| Are OAT/OCTs passive or active? |
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Definition
| They can be both – either facilitated diffusion (passive) or sodium-coupled secondary active transport (active) |
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Term
| Is PAH a cation or anion? And is it endogenous or exogenous? |
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Definition
| It is an exogenous organic anion |
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Term
| How do inulin and PAH differ in measuring GFR? |
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Definition
Inulin is completely filtered and neither secreted nor reabsorbed.
PAH is partially filtered and not reabsorbed but the rest is secreted (there is usually about 10% left in the blood though). |
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Term
| How does urate (base part of uric acid) react in the nephron? |
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Definition
| It is partially secreted but preferentially reabsorbed in exchange for secreted anions |
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Term
| Are bile salts, fatty acids, oxalates, prostaglandins, and urate anions or cations? |
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Definition
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Term
| Are acetylcholine, choline, creatinine, dopamine, epinephrine, guanidine, histamine, serotonin, NE, and thiamine anions or cations? |
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Definition
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Term
| What would result from acidification of the tubular lumen? |
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Definition
There would be an increase in the reabsorption of weak acids (HA) and an increase in the secretion of weak bases (B)
HA and B are more lipid soluble than A- and BH+ |
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Term
| Where is the proton concentration in the nephron the highest? |
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Definition
| It is 1000x higher in the distal tubule than the rest of the nephron |
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Term
| Is the proton pump located in the apical or basal membrane? |
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Definition
| It is on the apical membrane between the tubular lumen and the renal tubular cells |
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Term
| What is special about HA (undissociated/weak acids) and B (weak bases)? |
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Definition
| They are lipid soluble and can be secreted/reabsorbed easily |
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Term
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Definition
| Elevated levels of nitrogen-containing compounds in the blood. It can be caused by uregenesis in the kidneys. |
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Term
| What is the normal deep medullary osmotic gradient? What happens with tubular blockade by proteinacious gels? |
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Definition
1200 mosm/l
Tubular blockade destroys the medullary osmotic gradient and it takes 3 days to reestablish |
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Term
| Where is the nephron urea impermeable? |
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Definition
| Thick ascending loop of Henle, distal nephron, cortical collecting duct |
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Term
| Where is urea secreted? Where is it reabsorbed? |
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Definition
secreted = thin loop of Henle
reasbsorbed = proximal tubule and medullary collecting duct |
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