A&P 103B Mastering Hw Kidney 1

Match the following. Efferent arterioles, Afferent arterioles, vasa recta, peritubular capillaries, and Glomerular capillaries 1. May form meandering vessels or bundles of long straight vessels. 2. High pressure vessel that forces fluid and solutes into the glomerular capsule. 3. Play a role in urine concentration. 4. Low pressure, porous vessels that reabsorb solutes and water from the tubule cells. 5. Fenestrated vessels allow passage of all plasma elements, but not blood cells.

1. May form meandering vessels or bundles of long straight vessels. ; Efferent Arterioles 2. High pressure vessel that forces fluid and solutes into the glomerular capsule. ; Afferent Arterioles 3. Play a role in urine concentration. ; Vasa Recta 4. Low pressure, porous vessels that reabsorb solutes and water from the tubule cells. ; Peritubular capillaries 5. Fenestrated vessels allow passage of all plasma elements, but not blood cells. ; Glomerular capillaries

True or False? If the GFR is too low, needed substances may pass so quickly through the renal tubules that they are not absorbed and instead are lost in the urine. A) True B) False

B) False

-Part G Through the tubuloglomerular feedback mechanism, how would an increase in filtrate NaCl concentration affect afferent arteriole diameter? a) Afferent arteriole diameter would decrease. b) Afferent arteriole diameter would stay about the same. c) Afferent arteriole diameter would increase.

a) Afferent arteriole diameter would decrease. *High NaCl concentration in the filtrate at the JGA indicates that GFR is too high. By decreasing the diameter of the arteriole delivering blood to the glomerulus, HPg is decreased, resulting in lower GFR.

What is the function of the macula densa cells of the juxtaglomerular complex (JGC)? a) The macula densa cells monitor the NaCl content of the filtrate entering the distal convoluted tubule. b) The macula densa cells pass regulatory signals between the extraglomerular mesangial cells. c) The macula densa cells sense blood pressure in the afferent arteriole. d) The macula densa cells produce filtrate.

a) The macula densa cells monitor the NaCl content of the filtrate entering the distal convoluted tubule.

What is the juxtaglomerular apparatus? a) a system that regulates the rate of filtrate formation and systemic blood pressure b) a system for diluting urine c) a system for concentrating urine d) a system that protects the nephron from some chemicals found in blood

a) a system that regulates the rate of filtrate formation and systemic blood pressure

-Part E The myogenic mechanism of renal autoregulation primarily involves smooth muscle in which blood vessels? a) afferent arterioles b) efferent arterioles c) systemic arterioles d) glomeruli

a) afferent arterioles *By regulating afferent arteriole diameter, the myogenic mechanism affects HPg and therefore GFR. Under normal physiological conditions, this intrinsic control works to maintain GFR despite moderate changes in systemic blood pressure.

Which of the following is not reabsorbed by the proximal convoluted tubule? a) creatinine b) Na+ c) K+ d) glucose

a) creatinine

-Part C Which of the following are mechanisms of intrinsic control of glomerular filtration (renal autoregulation)? a) myogenic mechanism and tubuloglomerular feedback b) tubuloglomerular feedback and the renin-angiotensin mechanism c) sympathetic nervous system control and the renin- angiotensin mechanism d) myogenic mechanism and sympathetic nervous system control

a) myogenic mechanism and tubuloglomerular feedback *Both of these mechanisms occur strictly within kidney (i.e., intrinsic controls). The myogenic mechanism is mediated by smooth muscle within the afferent arteriole. In contrast, tubuloglomerular feedback is mediated by macula densa cells of the juxtaglomerular apparatus (JGA).

-Part D If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease? a) net filtration would decrease b) net filtration would not be altered c) net filtration would increase

a) net filtration would decrease *osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.

-Part H Granular cells of the juxtaglomerular apparatus (JGA) regulate GFR indirectly through which mechanism? a) renin-angiotensin mechanism b) myogenic mechanism c) sympathetic nervous system controls d) tubuloglomerular feedback mechanism

a) renin-angiotensin mechanism *When systemic blood pressure decreases, granular cells release renin which ultimately causes the formation of angiotensin II. Angiotensin II causes widespread vasoconstriction of systemic arterioles and the increase of blood volume due to aldosterone release.

Calculate the net filtration pressure if blood pressure in the glomerulus is unusually high, around 68 mm Hg. a) 83 mm Hg b) 23 mm Hg c) 15 mm Hg d) 113 mm Hg

b) 23 mm Hg

Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________. a) potassium b) sodium c) water d) glucose

b) sodium

-Part A Which of the following best describes glomerular filtration rate (GFR)? a) the volume of blood flowing through the glomerular capillaries per minute b) the volume of filtrate created by the kidneys per minute c) the volume of filtrate created at the glomerulus per liter of blood flowing through the glomerular capillaries d) the volume of urine leaving the kidneys per minute

b) the volume of filtrate created by the kidneys per minute *Fluid and small solutes that leave the glomerulus are collectively termed filtrate. Glomerular filtration is driven by glomerular hydrostatic pressure (HPg) and produces ~125 ml of filtrate per minute.

-Part D Macula densa cells of the juxtaglomerular apparatus (JGA) regulate GFR through which intrinsic mechanism? a) renin-angiotensin mechanism b) tubuloglomerular feedback c) sympathetic nervous system control d) myogenic mechanism

b) tubuloglomerular feedback *The JGA is a region of the nephron where the afferent arteriole and its associated tubule are closely apposed. This anatomical arrangement allows macula densa cells to adjust GFR according to the NaCl concentration in filtrate. This is called tubuloglomerular feedback because it allows the contents of the tubules (tubulo-) to affect the glomerular filtration rate.

-Part E Calculate the net filtration pressure if capillary hydrostatic pressure is 60 mm Hg, capillary osmotic pressure is 25 mm Hg, and capsular hydrostatic pressure is 10 mm Hg. a) 35 mm Hg b) 60 mm Hg c) 25 mm Hg d) 50 mm Hg

c) 25 mm Hg *60 - (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.

What would happen if the capsular hydrostatic pressure were increased above normal? a) Net filtration would increase above normal. b) Filtration would increase in proportion to the increase in capsular pressure. c) Net filtration would decrease. d) Capsular osmotic pressure would compensate so that filtration would not change.

c) Net filtration would decrease.

If the Tm for a particular amino acid is 120 mg/100 ml and the concentration of that amino acid in the blood is 230 mg/100 ml, the amino acid will ________. a) be actively secreted into the filtrate b) be completely reabsorbed by secondary active transport c) appear in the urine d) be completely reabsorbed by the tubule cells

c) appear in the urine

-Part A Which of the following substances is not normally found in filtrate? a) ions, such as sodium and potassium b) water and small solutes c) blood cells and large particles d) nitrogenous waste particles, such as urea

c) blood cells and large particles *both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane.

The macula densa cells respond to ________. a) changes in pressure in the tubule b) antidiuretic hormone c) changes in solute content of the filtrate d) aldosterone

c) changes in solute content of the filtrate

What type of capillaries make up the glomerulus? a) continuous b) sinusoids c) fenestrated d) vasa recta

c) fenestrated

-Part B GFR regulation mechanisms primarily affect which of the following? a) capsular hydrostatic pressure (HPc) b) capsular osmotic pressure (OPc) c) glomerular hydrostatic pressure (HPg) d) blood osmotic pressure (OPg)

c) glomerular hydrostatic pressure (HPg) *Much like other capillaries in the body, hydrostatic pressure within the glomerular capillaries produces net outward movement of fluid. Unique to glomerular capillaries, HPg is consistently higher than other capillaries (~55 mm Hg), which ensures the one-way movement of fluid and solutes out of the glomerulus under normal conditions.

-Part B What is the primary driving force (pressure) that produces glomerular filtration? a) gravity b) colloid osmotic pressure of blood c) hydrostatic pressure of blood (blood pressure)

c) hydrostatic pressure of blood (blood pressure) *hydrostatic pressure of blood forces fluid out of the glomerular capillaries.

-Part F What does a high concentration of NaCl in the renal tubule at the juxtaglomerular apparatus (JGA) most likely indicate? a) insufficient NaCl reabsorption due to low GFR b) excessive NaCl reabsorption due to high GFR c) insufficient NaCl reabsorption due to high GFR d) excessive NaCl reabsorption due to low GFR

c) insufficient NaCl reabsorption due to high GFR *After glomerular filtration, NaCl is actively reabsorbed at many locations along the renal tubule. If the filtrate is moving through the tubule quickly, less reabsorption is possible, so more NaCl gets left behind. This means that at the JGA, the NaCl concentration within the filtrate will be high.

How can an angiotensin converting enzyme inhibitor (ACE inhibitor) such as captopril be effective as an antihypertensive? a) ACE inhibitors reduce blood pressure by causing less aldosterone to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure. b) ACE inhibitors reduce blood pressure by causing less antidiuretic hormone to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure. c) ACE inhibitors reduce blood pressure by causing vasodilation in the blood vessels. d) ACE inhibitors reduce blood pressure by causing less aldosterone and antidiuretic hormone to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure. e) ACE inhibitors reduce blood pressure by causing less atrial natriuretic peptide to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure.

d) ACE inhibitors reduce blood pressure by causing less aldosterone and antidiuretic hormone to be released, resulting in more water output and a lowering of the blood volume, which lowers the blood pressure.

A nonfasting urine sample from an individual who has previously ingested donuts and a soft drink showed the presence of sugar (glucose). Which of the following statement explains the presence of the glucose in the urine? a) The individual has diabetes mellitus. b) The individual is glucose intolerant. c) Some glucose is always present in the urine. d) The individual exceeded the transport maximum.

d) The individual exceeded the transport maximum.

Which pressure is the chief force pushing water and solutes out of the blood and across the filtration membrane of the glomerulus? a) colloid osmotic pressure in the capsular space b) hydrostatic pressure in the capsular space (HPcs) c) colloid osmotic pressure in glomerular capillaries (OPgc) d) hydrostatic pressure in glomerular capillaries (HPgc)

d) hydrostatic pressure in glomerular capillaries (HPgc)

The fluid in the glomerular (Bowman's) capsule is similar to plasma except that it does not contain a significant amount of ________. a) glucose b) hormones c) electrolytes d) plasma protein

d) plasma protein

-Part C Which substance would be found in higher concentration if the membrane were damaged? a) glucose b) chloride c) creatinine d) protein

d) protein *large proteins are not normally filtered by a healthy glomerular membrane.