Physiology Test 2

25 July 2022
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question
which of the following is not a function of the kidneys?
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regulation of plasma temperature
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The primary function of the kidneys involves regulating the ________ and the ________ of plasma and interstitial fluid.
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volume : composition
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Once produced, urine travels through the ________ until it reaches the bladder, from which it is released into the external environment through the ________.
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ureter : urethra
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What hormone is secreted by the kidneys to increase red blood cell synthesis?
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erythropoietin
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Despite being less than 1% of body weight, the kidneys receive what percent of resting cardiac output?
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20%
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What are the conical sections of the renal medulla called?
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renal pyramids
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Where do the collecting ducts of the renal tubules drain?
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minor calyces
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What is the functional unit of the kidney?
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nephron
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What two structures make up the renal corpuscle?
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Bowman's capsule and glomerulus
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Blood leaves the ________ and enters the glomerulus.
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afferent arteriole
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Where does blood leaving the glomerulus go next?
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efferent arteriole
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After fluid passes through the entire proximal tubule, the fluid will enter the
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loop of Henle.
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What type of nephron is located within the outer region of the kidney and comprises nearly 80% of the nephrons?
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cortical
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The juxtaglomerular apparatus describes the unique region of the nephron where the
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afferent and efferent arterioles are in contact with the distal tubule.
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What capillaries come off of the efferent arterioles associated with cortical nephrons?
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peritubular
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What capillaries come off of the efferent arterioles associated with juxtamedullary nephrons?
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vasa recta
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Which of the following is the correct order of blood supply to the kidneys?
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renal artery, segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arteriole, glomerulus, efferent arteriole
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During what renal process are molecules selectively removed from the tubule lumen, moved into the interstitial space, and removed from the kidneys by the peritubular capillaries and the vasa recta?
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reabsorption
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The peritubular capillaries and vasa recta drain into what veins?
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interlobular
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As fluid moves out of the glomerular capillaries, it passes through gaps in the podocytes called slit pores, whose size is regulated by what?
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slit diaphragm
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What is the process whereby molecules are selectively transported from the peritubular fluid to the lumen of the renal tubules?
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secretion
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What is the process whereby protein-free plasma moves by bulk flow from the glomerulus into Bowman's capsules?
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glomerular filtration
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Which of the following forms the filtration barrier?
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capillary endothelial cells, basement membrane, and podocytes
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What is the sum of Starling's forces within the renal corpuscle called?
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glomerular filtration pressure
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What Starling force, which drives fluid out of the glomerulus, is relatively high (~60 mm Hg) due to the resistance of the efferent arterioles?
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glomerular capillary hydrostatic
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Which of the following pressures across the glomerular capillaries approaches zero?
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Bowman's capsule oncotic pressure
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Which of the forces across the glomerular capillaries tends to increase from the afferent to the efferent arteriole ends?
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glomerular oncotic pressure
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Which equation describes the calculation of glomerular filtration pressure (BC = Bowman's capsule and GC = glomerular capillary)?
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(PGC + ฯ€BC) - (PBC + ฯ€GC)
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Which of the following conditions would increase glomerular filtration pressure?
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increased protein in Bowman's space
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Which of the following equations is correct for calculating the filtered load?
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glomerular filtration rate ร— plasma concentration of solute
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Changes in mean arterial pressure have the potential to alter glomerular filtration rate by directly altering which of the following?
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glomerular capillary hydrostatic pressure
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What is the normal glomerular filtration rate?
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125 mL/min
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If the glomerular filtration rate is 150 mL/min, renal blood flow is 750 mL/min, and the plasma concentration of solute X is 10 ng/mL, then what is the filtration fraction?
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20%
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If the glomerular filtration rate is 150 mL/min, renal blood flow is 750 mL/min, and the plasma concentration of solute X is 10 ng/mL, then what is the filtered load of X?
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1500 ng/min
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Which of the following can increase the filtered load of a particular solute?
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increasing the rate of secretion
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Over what range of mean arterial pressure does glomerular filtration rate remain stable due to intrinsic regulation?
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80-180 mm Hg
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During myogenic regulation of glomerular filtration rate, an increase in mean arterial pressure will cause the
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afferent arterioles to constrict and thereby maintain a relatively constant glomerular filtration pressure.
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In tubuloglomerular feedback, an increase in glomerular filtration rate would increase the ________, thereby stimulating the release of a paracrine factor from the macula densa that would ________.
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flow of tubular fluid : constrict the afferent arteriole
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Contraction of mesangial cells results in a(n) ________, which decreases glomerular filtration.
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decrease in surface area of capillaries available for filtration
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Which of the following is NOT a mechanism whereby glomerular filtration rate is regulated?
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granular cell contraction
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A hemorrhage-induced decrease in mean arterial pressure will decrease glomerular filtration rate by intrinsic and extrinsic mechanisms; the extrinsic mechanisms act through
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the sympathetic nervous system.
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How does the sympathetic nervous system decrease glomerular filtration rate?
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stimulates constriction of both the afferent and efferent arterioles
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What is the primary barrier to reabsorption in the renal tubules?
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tubule epithelial cell
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What condition(s) must exist for a solute to be passively reabsorbed from the renal tubules?
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The solute must be able to permeate the membrane of the tubule epithelial cells, and the solute must be in greater concentration in the tubule fluid than plasma.
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Within the kidneys, what membrane has microvilli
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apical membrane of renal tubule epithelial cells
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The apical membranes of the tubular epithelial cells contain ________ that increase the surface area for reabsorption.
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microvilli
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The diffusion of water across a tubule is driven by differences in ________ across the membrane.
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osmolarity
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When the solute concentration is high enough in the lumen of the renal tubules such that all of the carrier proteins or pumps for that solute are occupied, the system is operating at
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transport maximum.
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The concentration of glucose in tubular epithelial cells is maintained in an elevated state by what type of transporter on the apical membrane?
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sodium-linked secondary active transporter
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Which of the following is FALSE concerning glucose transport across the proximal tubule?
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Glucose moves by paracellular transport.
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Which of the following is FALSE concerning renal handling of glucose?
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The maximum rate of glucose filtration is 375 mg/min.
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Which of the following substances is NOT secreted at any point into the renal tubules?
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sodium
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By the time filtrate reaches the loop of Henle, what percentage of the sodium and water has been reabsorbed?
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70%
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By the time the filtrate reaches the loop of Henle, the reabsorption of water and ions has
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left the filtrate iso-osmotic.
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Which of the following is NOT an accurate description of differences between epithelial cells of the proximal and distal tubules
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greater paracellular transport in the epithelial cells of the distal tubule
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In diabetes mellitus, why does polyuria occur?
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Hyperglycemia causes some glucose to remain in the renal tubules which pulls water with it by osmosis.
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What is the brush border?
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microvilli on the apical membrane of the proximal tubule
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Most reabsorption occurs in the ________ and is ________.
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proximal tubule : not regulated
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Tubular epithelial cells of the collecting duct and distal tubule contain receptors for what hormone that stimulates sodium reabsorption?
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aldosterone
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Tubular epithelial cells of the collecting duct and distal tubule contain receptors for what hormone that stimulates water reabsorption?
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antidiuretic hormone
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What creates the osmotic gradient in the renal medulla?
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special transport systems of the loops of Henle of juxtamedullary nephrons
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Substances can enter the renal tubules by what renal processes?
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both filtration and secretion
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The amount of a substance excreted from the kidneys is calculated by which of the following equations?
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filtration + secretion - reabsorption
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Solutes that enter the lumen of the renal tubules are excreted unless they are
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reabsorbed
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If the amount of solute excreted per minute is greater than the filtered load, then the NET effect on the solute is
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secretion into the renal tubules.
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Which of the following equations for determining clearance is correct?
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clearance = excretion rate / plasma concentration
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Which of the following equations for determining clearance is correct?
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clearance = (urine concentration ร— urine flow rate) / plasma concentration
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Calculate renal clearance of X given the following information: GFR = 100 mL/min, urine flow rate = 5 mL/min, plasma concentration of X = 10 mg/mL, urine concentration of X = 50 mg/mL.
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Y is reabsorbed.
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Given that GFR is 125 mL/min and the clearance of substance Y is 200 mL/min, which of the following MUST be true of the renal handling of substance Y?
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Y is freely filterable.
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The clearance of what substance provides the best estimate of glomerular filtration rate?
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insulin
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The clearance of what substance provides the best estimate of renal blood flow rate?
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PAH
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The clearance of which of the following substances is normally zero?
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glucose
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If a substance is neither reabsorbed nor secreted, then its excretion rate is equal to the
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filtered load.
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What structure is formed by the thickening of the smooth muscle cell wall surrounding the bladder that regulates the flow of urine from the bladder?
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internal urethral sphincter
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How is urine moved through the ureter?
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wavelike contractions of the ureter
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Which muscle(s) that regulate(s) micturition is/are under involuntary control?
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detrusor and the internal urethral sphincter
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Which of the following occurs during micturition?
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The detrusor muscles contract, muscles of the internal urethral sphincter relax, and muscles of the external urethral sphincter relax.
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Stretching of the bladder reflexively causes all of the following EXCEPT
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excitation of sympathetic neurons, causing the internal urethral sphincter to relax.
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What effect does the sympathetic nervous system have on micturition?
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Sympathetic activity excites muscles of the internal urethral sphincter inhibiting micturition.
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Which of the following is smooth muscle?
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both the internal urethral sphincter and detrusor muscle
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To voluntarily control urination, the ________ nervous system innervates the ________.
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somatic : external urethral sphincter
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During micturition, neural activity to sphincters or detrusor muscles from which of the following is increased?
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parasympathetic nervous system only
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In older children and adults, the cerebral cortex is able to block micturition by inhibiting nerve activity to the
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detrusor muscle only.
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Substance X is freely filtered at the glomerulus. 3 mmole X is filtered, 2 mmole X is reabsorbed, and 2 mmole X is secreted per minute. How much X is excreted per minute?
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3 mmole
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During tubuloglomerular feedback of glomerular filtration rate, paracrines secreted from what structure(s) cause constriction of the afferent arteriole?
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macula densa
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In comparison to the distal tubule, the proximal tubule has a
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leakier epithelium and a larger apical surface area.
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What is the site where filtrate enters renal tubules?
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Bowman's capsule
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Most filtered solutes and water are reabsorbed in what region?
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proximal tubule
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Filtrate moves from what structure to the loop of Henle?
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proximal tubule
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Located entirely within the cortex, reabsorption of water and certain solutes from which region is under hormonal control?
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distal tubule
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In juxtamedullary nephrons, which region sets up the medullary osmotic gradient?
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loop of Henle
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Which tubule drains into the minor calyces?
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collecting duct
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What structure filters the blood to regulate its composition?
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kidneys
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What structure stores urine prior to micturition?
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bladder
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What structure transports urine from the kidneys to the bladder?
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ureter
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What structure transports urine from the bladder to outside of the body?
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urethra
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Which of the following describes movement from glomerular capillaries into Bowman's capsule
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filtration
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Which of the following describes movement from renal tubules into the peritubular capillaries?
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reabsorption
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Which of the following describes movement from peritubular capillaries into the renal tubules?
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secretion
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Which of the following describes elimination of urine from the body?
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excretion
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Constriction of which vessel, by intrinsic or extrinsic mechanisms, decreases glomerular filtration rate?
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afferent arteriole
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Substances that are reabsorbed from the proximal tubule enter which blood vessel?
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peritubular capillary
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Filtration occurs across which capillary bed?
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glomerulus
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After blood is filtered in the renal corpuscle, the blood continues moving through which blood vessel to another capillary bed?
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efferent arteriole
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Which capillary bed dips down into the renal medulla with the loop of Henle?
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vasa recta
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Which of the following are modified smooth muscle cells around the glomerulus that contract to decrease the surface area of the glomerulus available for filtration?
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mesangial cells
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Which of the following are epithelial cells of Bowman's capsule that form part of the filtration barrier?
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podocytes
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Which cells of the afferent arteriole secrete renin?
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granular cells
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Which cells of the distal tubule secrete a paracrine in response to changes in the filtrate flow rate?
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macula densa cells
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What is the GFR/renal plasma flow equal to?
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filtration fraction
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What is the GFR ร— plasma concentration equal to?
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filtered load
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What is the excretion rate/plasma concentration equal to?
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clearance
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What is the urine concentration ร— urine flow rate equal to?
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excretion rate
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What is the (urine concentration ร— urine flow rate)/plasma concentration equal to?
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clearance
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What is the (clearance of PAH)/(1 - hematocrit) equal to?
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renal blood flow
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What is the region of the kidney where the renal artery and vein enter?
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hilus
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What two structures make up the renal corpuscle?
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Bowman's capsule and the glomerulus
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What are the three components of the loop of Henle?
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descending limb, thin ascending limb, and thick ascending limb
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What are a small percentage of the nephrons in the kidneys that function in the maintenance of the osmotic gradient in the medullary region of the kidney called?
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juxtamedullary nephrons
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Which capillaries branch from efferent arterioles of cortical nephrons and which branch from efferent arterioles of juxtamedullary nephrons?
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peritubular and vasa recta, respectively
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What are the specialized cells of the juxtaglomerular apparatus in the distal tubule called?
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macula densa
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What are the specialized cells of the juxtaglomerular apparatus in the afferent arteriole (and, to a lesser extent, the efferent arteriole) called?
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granular cells
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Which layer of the filtration barrier in Bowman's capsule is the primary barrier to the movement of protein from the capillary?
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basement membrane
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Under normal conditions, the osmotic pressure gradient across the glomerular capillaries tends to move water
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back into the capillaries.
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Which of the four Starling forces for glomerular filtration is incorrectly paired with the direction it favors (filtration or absorption)?
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glomerular capillary osmotic pressure : filtration
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Given a GFR of 100 mL/min, and a plasma concentration of solute of 10 mg/mL, what is the filtered load of this solute?
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1000 mg/min
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When carrier proteins are saturated, they are said to be working at what?
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transport maximum
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The clearance of ________ provides a measure of renal plasma flow rate.
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PAH
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The clearance of what substance, which is not produced in the body but must be injected, provides a measure of glomerular filtration rate?
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inulin
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The clearance of what substance, a natural by-product of muscle metabolism, provides a non-invasive estimate of glomerular filtration rate?
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creatinine
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In terms of controlling micturition, the somatic nervous system innervates the ________, the parasympathetic nervous system innervates the ________, and the sympathetic nervous system innervates the ________.
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external urethral sphincter : detrusor muscle : internal urethral sphincter
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The micturition reflex is activated by the stretch of the bladder, which activates what?
answer
stretch receptors