Term
| What percentage of cardiac output do the kidneys take in? |
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Definition
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Term
| How do you tell “good pee” from “bad pee”? |
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Definition
| A combination of values from both blood and urine tests |
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Term
| True or False: the kidneys excrete approx. 1-3 L/day and filter 180 L/day. |
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Definition
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Term
| What percentage of filtered volume is excreted in the urine by nephrons and what percent is reabsorbed back into the peritubular capillaries? |
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Definition
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Term
| When the 65-75% of fluid passing through the proximal tubule is reabsorbed, is the fluid hypotonic or hypertonic? |
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Definition
| Trick question, its is reabsorbed at the same osmolality as the filtrate. |
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Term
| What perecent of plasma entering the renal artery makes it through the glomerular capillaries? |
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Definition
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Term
| Which part of the nephron is essential in regulating K, Na, H2O, and acid? |
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Definition
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Term
| What percent of nephrons are cortical versus juxtamedullary? |
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Definition
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Term
| What is the juxtaglomerular apparatus and what does it do? |
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Definition
| It is a group of rennin-containing smooth muscle cells on the afferent arteriole, it responds to the adjoining macula densa signals when Cl absorption is high/low and it regulates glomerular filtration rate. |
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Term
| True or False: fluid is filtered across these 3 structures in this order - fenestrae of endothelium, 3 part basement membrane, thru slit pores between podocytes and visceral epithelium. |
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Definition
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Term
| The glomerulus is an ultrfiltration device, what does this mean? |
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Definition
| It is filtration through a barrier that excludes colloidal (protein) molecules but allows small molecules to pass indiscriminately. |
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Term
| Of the 3 different tissue layers in the glomerulus, which one is the main filtration barrier? |
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Definition
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Term
| Why is albumin excluded from filtration in the glomerulus? |
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Definition
| Because the filtration layer has fixed negative charges repulsing the negative charges on albumin. Both size and charge are its limitation (positive charges can make it through). |
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Term
| The largest number of kidney diseases affect which crucial component of the nephron? |
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Definition
| The glomerulus. This can lead to loss of the entire nephron. Proteinuria is an early warning sign of damage. |
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Term
| True or False: what makes glomerular capillaries unique is their low filtration coefficient, low filtering force, long length, high resistance, filtration slows or stops before its efferent end. |
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Definition
| False, it is due to high filtration coefficient, high filtering force, short length, low resistance, and filtration slows or stops before its efferent end. |
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Term
| What is colloid osmotic pressure? |
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Definition
| It is where proteins left behind in the glomerular capillaries concentrate sufficiently to raise osmotic pressure near the efferent arterioles. |
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Term
| Over what range does renal blood flow and glomerular filtrate rate change as mean arterial pressure varies between 90-1700mmHg. |
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Definition
| The rates are nearly constant, and only drop off below 90mm Hg |
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Term
| True or False: renal blood flow and glomerular fitration rate are regulated by nerves. |
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Definition
| False, they are autoregulated. |
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Term
| What determines renal blood flow and GFR? |
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Definition
| Renal - sum of afferent and efferent resistances, GFR - ratio of eff/aff resistances and capillary pressure. |
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Term
| What would happen if you increased afferent tone or efferent tone in nephron sphincters? |
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Definition
| Afferent - decrease pressure, GFR, and renal perfusion; efferent - increase pressure, GFR, but decrease renal perfusion |
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Term
| How are afferent and efferent tone regulated differently? |
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Definition
| Afferent - direct SNA, Ca mediated response to stretch, tubuloglomerular feedback, mild response to angiotensin II; efferent- contract preferentially to locally produced angiotensin II |
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Term
| What clinical use are ACE inhibitors used for in kidneys? |
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Definition
| To slow renal failure by reducing filtration pressure |
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Term
| What is the equation for excretion rate? |
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Definition
| Excretion rate = [urine] x urine flow rate, E=U x V |
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Term
| What is the formula for filtration rate? |
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Definition
| Filtration rate = GFR x P(plasma concentration) |
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Term
| What is the formula for clearance or for GFR? |
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Definition
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Term
| True or False: Normal Glomerular filtration rates for men and women are 85-125ml/min and 75-115 ml/min respectively. |
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Definition
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Term
| True or False: the normal [Creatinine] is .5-1.3 mg/dL. |
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Definition
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Term
| As creatinine concentration ________, GFR _________? |
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Definition
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Term
| If a substance has a clearance that is greater than GFR then it is ________, and if it has a clearance less than GFR it is ___________. |
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Definition
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Term
| In the early proximal tubule which antiporter is the most important mechanism? |
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Definition
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Term
| The reabsorbate in the proximal tubule is always: hyperosmotic, isosmotic, hypoosmotic? |
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Definition
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Term
| True or False: in the proximal tubule urea is absorbed by an active mechanism. |
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Definition
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Term
| What two ions are the epithelium tight junctions leaky to in the proximal tubule? |
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Definition
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Term
| What is glomerulotubular balance in the proximal tubule? |
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Definition
| The rate of fluid reabsorption in the proximal tubule is a constant percentage of GFR, 65-70%. |
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Term
| True or False: the reabsorption mechanisms in the latter half of the proximal tubule use the exact same mechanisms as the first half. |
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Definition
| False, they use different mechanisms because the fluid composition has changed |
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Term
| Fluid absorption in the proximal tubule depends on the rate of uptake by _________ _____________? |
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Definition
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Term
| Sometimes the peritubular capillaries can’t reabsorb fluid fast enough from the proximal tubule causing a backleak of salt, what happens with a moderate backleak versus a high back leak? |
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Definition
| Moderate - can still have a high reabsorption rate, High - has low reabsorption rate |
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Term
| Name the part of the nephron that reabsorbs 25% of salt in filtrate, impermeable to water, absorbs 2Cl and 1 Na thru cell, has +20mV potential that drives passive absorption of Mg and Ca thru tight junctions, minimal K absorption, site of action of loop diuretics is Na/2Cl/K transporter, and glomerulotubular balance is rate-limited by [Cl]. |
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Definition
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Term
| Name the part of the nephron that absorbs 5% of salt in filtrate, impermeable to water, no paracellular flux or electrical potential, has glomerulotubular balance, Na/Cl transporter blocked by thiazide diuretics, mediates hormonally regulated Ca reabsorption. |
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Definition
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Term
| Name the part of the nephron that is the principal site where Na, K, H, and water are regulated, where ADH and aldosterone principally act, has tight junctions with lumen potential of -50mV, with very little glomerulotubular balance, and made of principal cells and intercalated cells. |
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Definition
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Term
| What type of cell in the nephron reabsorb water due to ADH, modulate the last 1-2% of filtered Na with aldosterone, secrete K which can be affected by aldosterone, is affected by potassium sparing diuretics like amiloride and spironolactone. |
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Definition
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Term
| What type of cell in the nephron do not transport Na or water, but do reabsorb K and HCO3, and acidify the urine by excreting H? |
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Definition
| a-intercalated cells in collecting tubule. |
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Term
| What type of cell in the nephron has only primary proton pumps which pump protons into the plasma, and HCO3 is secreted into the urine, and help acidify the body plasma that has become alkaline? |
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Definition
| B-intercalated cells in collecting tubule. |
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Term
| What are the two steps required to form concentrated urine? |
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Definition
| 1- Counter current multiplication by the loops of Henle increasing osmolality of extracellular fluid near collecting ducts, and 2 - the modulation of ADH and water channels to reabsorb water in the principal cells of the collecting duct. |
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Term
| Describe the basics of how the counter-current multiplier works. |
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Definition
| The thin ascending loop throws NaCl into the interstitium from the constantly osmolar fluid passing through the tubule, which creates a driving force for water to enter the interstitium from the thin descending loop. This cycle repeats itself and multiplies due to the constant flow of fresh fluid. |
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Term
| What is the name of counter current exchanger capillary that supplies blood and O2 to the interstitium without dissipating the osmotic gradient? |
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Definition
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Term
| Which molecule activates urea channels in the inner medullary collecting tubule which allows it to diffuse into the interstitium which can double the osmolality of the medulla when urine is being concentrated? |
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Definition
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Term
| Brain osmoreceptors lie outside the blood brain barrier to detect fluid osmolality, what is osmolality that the body tries to keep constant? |
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Definition
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Term
| What are the large-bodied cells that osmoreceptors synapse with that release ADH from the posterior pituitary? |
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Definition
| Supraoptic and paraventricular nerves |
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Term
| Which type of receptor does ADH bind to in the collecting tubule to insert more type-2 aquaporins? |
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Definition
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Term
| True or False: drinking behavior can maintain water balance without good renal function. |
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Definition
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Term
| How does circulating volume being either normal or significantly depleted modify the kidneys priorities? |
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Definition
| When volumes are normal water balance is regulated to keep osmolality constant, when volumes are depleted volume stimuli for ADH and thirst override the need to maintain that osmolality constant. |
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Term
| True or False: due to normal kidney function humans tend toward hypernaturemia. |
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Definition
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Term
| What two factors contribute to the fact that increased distal solute load can overwhelm normal mechanisms that dilute and concentrate urine? |
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Definition
| Increased medullary flow would wash out counter-current osmotic gradients, and high flow rates would reduce the amount of time available for the fluid to become osmotically equilibriated with interstitium. |
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Term
| Rank the following from highest to lowest in total percentage of body water - child, man, woman. |
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Definition
| Child, man, woman; the percentage decreases as you age |
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Term
| What proportion of body water is in the intracellular, extracellular, and plasma compartments? |
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Definition
| 2/3 in intracellular, 1/3 in extracellular, and the plasma takes ¼ of the extracellular water with the rest going to interstitial fluid |
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Term
| What is osmotic pressure? |
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Definition
| The hydrostatic pressure that has to be applied to a compartment to prevent water flowing down its osmotic gradient. |
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Term
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Definition
| The total mmoles of all independent solute molecules per kg of water |
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Term
| What is an ineffective osmole? |
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Definition
| When urea concentrations increase osmolality without causing cell shrinkage. |
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Term
| What is the difference between an ideal and non-ideal osmotic response and list a tissue type for each? |
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Definition
| An ideal response, like in skeletal muscle, is when a cell changes its volume inversely proportional to the osmolality, a non-ideal response, like in the brain, is where the cell adjusts its volume acutely but then has either an RVI or RVD |
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Term
| Since the extra osmolality in the plasma causes an osmotic pressure of 25 mm Hg by what two ways does the body maintain cell volume despite this oncotic pressure (osmotic pressure difference)? |
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Definition
| Maintaining a constant extracellular osmolality and use of energy to keep osmoles on the outside of the cell from accumulating inside. |
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Term
| The following symptoms are likely due to what problem - apathy, somnolence, disorientation and coma, severe thrist. |
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Definition
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Term
| The following symptoms are likely due to what problem - difficulty concentrating, increasing severity causes anorexia/nausea/vomiting, worsening severity causes coma and death. |
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Definition
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Term
| In hypo and hyperosmolar syndromes why is it that aggressive treatment is appropriate early but be disastrous if begun 48 hours later? |
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Definition
| If treated acutely and symptoms are serious the best course of action is to correct osmolality, if however the patient has had time for the cells to have RVI or RVD then aggressive treatment would cause a dangerous rebound reaction to the change in osmolality. |
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Term
| True or False: as long as ADH and thirst regulate plasma to a constant osmolality the volume of the ECF depends on the total amount of solute/Na in that compartment. |
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Definition
| True, so changing the amount of Na in the body does not change its concentration because the body will adjust the amount of water to maintain osmolality |
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Term
| What are the two important sensors in the kidney? |
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Definition
| The volume sensor in the afferent arteriolar stretch and the distal salt load at the macula densa. |
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Term
| Why does it take so long for the body to adjust to the daily addition or subtraction of salt? |
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Definition
| The feedback system starts to work as soon as enough Na is added to result in significant volume expansion changing control signals. |
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Term
| What is aldosterones function and which cell is its most important site of action? |
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Definition
| It works in the principal cells of the collecting tubule to reabsorb the last 1-2% of the original Na that was filtered. |
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Term
| What is the direct effect of angiotensin II on the proximal tubule? |
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Definition
| Increases Na reabsorption by stimulating Na/H transport. |
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Term
| What is the purpose of atrial natriuretic peptides and natriuretic hormones? |
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Definition
| ANP slow Na absorption in response to volume expansion states, and NH causes Na loss by inhibiting the Na/K ATPase in the proximal tubule |
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Term
| As volume depletion increases in the body the SNA to kidney increase their firing rate, what effect do these efferents have at low, intermediate, and high frequencies? |
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Definition
| Low - increases renin secretion via b1 receptors, Medium - increases Na reabsorption directly via a1 receptors in the proximal tubule and thick ascending limb, High - decreases blood flow by increasing tone to afferent arterioles |
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Term
| What happens to salt and water absorption in the proximal tubule when oncotic pressure or hydrostatic pressure increases in the peritubular capillaries? |
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Definition
| Oncotic - would increase absorption, hydrostatic - decrease absorption |
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Term
| True or False: extracellular volume is regulated primarily by adjustments to sodium balance |
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Definition
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Term
| Identify the 3 volume-related stimuli that interact with JG cells to release renin and ultimately aldosterone. |
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Definition
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Term
| Understand this pathway for aldosterone creation. |
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Definition
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Term
| Recognize the transporters in the latter proximal tubule. |
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Definition
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Term
| Recognize the transporters in the early proximal tubule. |
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Definition
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Term
| Recognize the transporters in the distal tubule. |
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Definition
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Term
| Recognize the transporters in the thick ascending limb. |
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Definition
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Term
| Recognize the transporters in the principle cells in the collecting tubule. |
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Definition
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Term
| Recognize the transporters in the a-intercalated cells in the collecting tubule. |
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Definition
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