BIO 431 URINARY SYSTEM EXAM
QUESTIONS WITH CORRECT ANSWERS
Juxtaglomerular (JG) Apparatus - Answer-Located between ascending loop & the
afferent arteriole
regulates blood pressure in the glomerulus (autoregulation)
Asc. loop contains macula densa cells
Aff. arteriole contains smooth muscle cells called juxtaglomerular cells
1.Glomerular Filtration
2.Reabsorption
3.Secretion - Answer-Steps in Urine filtration
Excretion rate of solute - Answer-filtration rate of solute + secretion rate of solute −
reabsorption rate of solute
Glomerular Filtration - Answer-Driven by blood pressure (aka GBHP)& opposed by
capsular hydrostatic pressure (CHP) & blood colloid osmotic pressure (BCOP)
150-180 liters of filtrate/day
Net Filtration Pressure (NFP) - Answer-the difference between net hydrostatic pressure
and net osmotic pressure
GBHP-CHP-BCOP
Glomerular filtration rate (GFR) - Answer-the amount of filtrate formed by both kidneys
each minute
125 ml/min (males) & 105 ml/min (women)
High GFR - Answer-substances pass too quickly & are not reabsorbed
Low GFR - Answer-nearly all substances are reabsorbed & waste excretion is
inadequate
Renal Autoregulation
Neural Regulation
Hormonal Regulation - Answer-regulators that controls GFR
Renal Autoregulation - Answer-nephrons adjust their own blood flow and GFR without
external (nervous or hormonal) control
Myogenic mechanism of Renal Autoregulation - Answer-Smooth muscle cells in afferent
arterioles contract in response to elevated blood pressure
decrease GFR
, Tubuloglomerular feedback of Renal Autoregulation - Answer-High GFR reduces
reabsorption
Macula densa inhibits release of nitric oxide by JG cells
Afferent arterioles constrict
decrease GFR to allow reabsorption
Neural Regulation - Answer-Kidneys are richly supplied by sympathetic fibers.
Strong stimulation (exercise or hemorrhage)-afferent arterioles are constricted.
decrease GFR
Urine output is reduced
More blood is available for other organs
Hormonal Regulation - Answer-Angiotensin II constricts afferent & efferent arterioles,
decreasing GFR
Atrial natriuretic peptide (ANP) relaxes mesangial cells, increasing capillary surface
area & GFR
Angiotensin II - Answer-Low blood volume or pressure:
Constriction of afferent and efferent arterioles
Decrease GFR
Atrial natriuretic peptide (ANP) - Answer-Stretching of atria of the heart:
Relaxation of mesangial cells in glomerulus increases capillary surface area available
for filtration
+urine output
Increase GFR
Much of the filtrate is reabsorbed (returned to the blood), especially water, glucose,
amino acids, & ions
Secretion helps to manage pH & remove toxic & foreign substances from the blood -
Answer-Tubular Reabsorption & Secretion
Paracellular reabsorption (next to) - Answer-Passive fluid leakage between cells
Transcellular reabsorption - Answer-Directly through tubule cells crossing both the
apical & basolateral membranes
Primary active transport - Answer-Uses ATP, like Na+/K+pumps
At rest, accounts for 6% total body ATP use
Secondary active transport - Answer-Driven by ion's electrochemical gradient
Symporters move substances in same direction
Antiporters move substances in opposite directions
Water Reabsorption Mechanisms - Answer-Obligatory water reabsorption -90%
Facultative water reabsorption -10%
QUESTIONS WITH CORRECT ANSWERS
Juxtaglomerular (JG) Apparatus - Answer-Located between ascending loop & the
afferent arteriole
regulates blood pressure in the glomerulus (autoregulation)
Asc. loop contains macula densa cells
Aff. arteriole contains smooth muscle cells called juxtaglomerular cells
1.Glomerular Filtration
2.Reabsorption
3.Secretion - Answer-Steps in Urine filtration
Excretion rate of solute - Answer-filtration rate of solute + secretion rate of solute −
reabsorption rate of solute
Glomerular Filtration - Answer-Driven by blood pressure (aka GBHP)& opposed by
capsular hydrostatic pressure (CHP) & blood colloid osmotic pressure (BCOP)
150-180 liters of filtrate/day
Net Filtration Pressure (NFP) - Answer-the difference between net hydrostatic pressure
and net osmotic pressure
GBHP-CHP-BCOP
Glomerular filtration rate (GFR) - Answer-the amount of filtrate formed by both kidneys
each minute
125 ml/min (males) & 105 ml/min (women)
High GFR - Answer-substances pass too quickly & are not reabsorbed
Low GFR - Answer-nearly all substances are reabsorbed & waste excretion is
inadequate
Renal Autoregulation
Neural Regulation
Hormonal Regulation - Answer-regulators that controls GFR
Renal Autoregulation - Answer-nephrons adjust their own blood flow and GFR without
external (nervous or hormonal) control
Myogenic mechanism of Renal Autoregulation - Answer-Smooth muscle cells in afferent
arterioles contract in response to elevated blood pressure
decrease GFR
, Tubuloglomerular feedback of Renal Autoregulation - Answer-High GFR reduces
reabsorption
Macula densa inhibits release of nitric oxide by JG cells
Afferent arterioles constrict
decrease GFR to allow reabsorption
Neural Regulation - Answer-Kidneys are richly supplied by sympathetic fibers.
Strong stimulation (exercise or hemorrhage)-afferent arterioles are constricted.
decrease GFR
Urine output is reduced
More blood is available for other organs
Hormonal Regulation - Answer-Angiotensin II constricts afferent & efferent arterioles,
decreasing GFR
Atrial natriuretic peptide (ANP) relaxes mesangial cells, increasing capillary surface
area & GFR
Angiotensin II - Answer-Low blood volume or pressure:
Constriction of afferent and efferent arterioles
Decrease GFR
Atrial natriuretic peptide (ANP) - Answer-Stretching of atria of the heart:
Relaxation of mesangial cells in glomerulus increases capillary surface area available
for filtration
+urine output
Increase GFR
Much of the filtrate is reabsorbed (returned to the blood), especially water, glucose,
amino acids, & ions
Secretion helps to manage pH & remove toxic & foreign substances from the blood -
Answer-Tubular Reabsorption & Secretion
Paracellular reabsorption (next to) - Answer-Passive fluid leakage between cells
Transcellular reabsorption - Answer-Directly through tubule cells crossing both the
apical & basolateral membranes
Primary active transport - Answer-Uses ATP, like Na+/K+pumps
At rest, accounts for 6% total body ATP use
Secondary active transport - Answer-Driven by ion's electrochemical gradient
Symporters move substances in same direction
Antiporters move substances in opposite directions
Water Reabsorption Mechanisms - Answer-Obligatory water reabsorption -90%
Facultative water reabsorption -10%
