BIO 2301 HUMAN PHYSIOLOGY -
LECTURE EXAM #4 QUESTIONS WITH
COMPLETE SOLUTIONS
Capsular hydrostatic pressure (CHP) - ANSWER-- This pressure also opposes
filtration
- Due to the presence of fluid and solutes in Bowman's capsule
- Causes fluid and solutes to be pushed out of the Bowman's capsule and go back to
the glomerulus
Net filtration pressure (NFP) equation - ANSWER-GHP - (GOP + CHP)
Glomerular filtration rate (GFR) - ANSWER-- 125 ml/min
- Definition: the volume of filtrate formed every minute - it is directly related to the net
filtration pressure
Clearance - ANSWER-- A measure of how quickly a substance is removed/cleared
from your blood done either by your kidneys or liver
- For substances handled by the kidneys, it is determined by measuring the amount
of that substance in your blood and your urine over a 24 hour period
Determining GFR by measuring clearance - ANSWER-- If you measure the
clearance of a substance that is removed from the blood only by filtration and not by
reabsorption or secretion
- The best substances to use is inulin but it is only used experimentally, not clinically
What substance do they used clinically to determine someone's GFR? - ANSWER--
Creatinine
- Creatinine is filtered and not reabsoprbed and only minimally secreted so the
clearance of creatinine is about equal to GFR
- Advantage of using this: normal product secreted by a person so you don't have to
give it to them, just collect and measure the blood
Why is it important that GFR is regulated? (Renal autoregulation) - ANSWER-It must
stay at 125 ml/min because the rate or reabsorption depends on the rate of filtration
What happens if GFR goes below normal? - ANSWER-Everything moves through
the nephron so slowly that you have time to reabsorb more than usual and you end
up saving waste products in the blood
What happens if GFR goes above normal? - ANSWER-Everything rushes through
the nephron so quickly that you don't have time to reabsorb and you end up losing
substances in the urine that you want to keep
How do the kidneys keep GFR within a normal range? - ANSWER-If the GFR is not
normal, it can be brought back to normal by changing the diameter of the afferent
,arteriole which alters the volume of blood coming to the afferent arteriole and the
glomerulus
Parameters monitor in renal autoregulation - ANSWER-- Blood pressure: the
pressure as it flows through the afferent arterioles because this affects the
glomerular hydrostatic pressure, the main pressure that causes filtration and affects
GFR
- Tubular osmolarity: concentration of the filtrate as it flows through the distal
convoluted tubules
Response to increased BP or increased osmolarity - ANSWER-- This means GFR is
high
- Constriction of the afferent arteriole which will decrease blood volume and get GFR
down to normal
Response to decreased BP or decreased osmolarity - ANSWER-- This means GFR
is low
- Dilation of the afferent arteriole to increase the blood volume and get GFR up to
normal
Kidneys also work to fix a low ______________________ - ANSWER-systemic BP
Renin-Angiotensin-Aldosterone System - ANSWER-Works to fix a low systemic BP
(think of separately as the renal autoregulation)
Renin - ANSWER-- Produced by specialized cells of the afferent arteriole (called
juxtaglomerular (JG) cells)
- Released when BP is low
- Converts angiotensinogen to angiotensin I which then gets converted to
angiotensin II by ACE
Angiotensin II - ANSWER-- Causes vasoconstriction which increased BP
- Causes release of aldosterone
Aldosterone - ANSWER-Causes Na+ and water reabsorption (saves them) which
causes an increase in blood volume and thereby increases BP
What effect does the sympathetic nervous system have on the renal system? -
ANSWER-- These occur when BP is low
- Constriction of afferent arterioles: causes decreased urine formation so the water
remains in the blood and increases BP
- Increased renin secretion: acts to increase BP
What is involved in reabsorption? - ANSWER-- Proximal convoluted tubule
- Nutrients
- Excretion by lack of reabsorptive mechanism
- Reabsoption of sodium and water
- Collecting duct
, What are the special capillaries that run parallel to the loop of Henle on some
nephrons? - ANSWER-Vasa recta
What are the three processes involved in making urine? - ANSWER-- Filtration
- Reabsorption
- Secretion
Filtration - ANSWER-- Fluid and solutes leave the blood of the glomerulus and enter
into the renal tubule at the Bowman's capsule
- This is due to a pressure gradient
- It is a relatively nonspecific process
- Anything that is small enough to get through the holes in the glomerulus will be
present in the filtrated, and that includes a lot of stuff you do not want to lose from
the body
Reabsorption - ANSWER-Substances are taken out of the filtrate at the proximal
convoluted tubule and put back into the blood of the peritubular capillaries
Secretion - ANSWER-Substances/wastes are taken out of the blood in the
peritubular capillaries, put into the filtrate, and will come out in the urine
Glomerular membrane - ANSWER-- The glomeruli are tufts of capillaries present in
the cortex of the kidney
- Since they are capillaries, blood is flowing through them
- Unique in 2 ways: they have a fenestrated endothelium (has holes in it) and they
are both fed and drained by arterioles (usually the arteriole only brings blood)
What does the filtration require? - ANSWER-A filter and a pressure gradient
What do the fenestrations provide? - ANSWER-The filter
Where does the pressure gradient come from? - ANSWER-- The fact that the
glomeruli are both fed and drained by arterioles
- Arterioles are high pressure vessles so a high pressure coming in (via afferent
arteriole) and high pressure leaving (via efferent arteriole)
Is pressure higher going in or out of the glomerulus? Why? - ANSWER-Afferent
arterioles have a larger diameter than efferent aterioles so there is a higher pressure
coming into the glomerulus (afferent) than leaving it (efferent)
Three filtration pressures at work at the glomerulus - ANSWER-- Glomerular
hydrostatic pressure (GHP)
- Glomeruluar Osmotic Pressure (GOP)
- Capsular hydrostatic pressure (CHP)
Glomerular hydrostatic pressure (GHP) - ANSWER-- Main pressure pushing for
filtration
- Due to the volume of blood in the glomerulus and the blood pressure in the
glomerulus (GHP = BV x BP)
LECTURE EXAM #4 QUESTIONS WITH
COMPLETE SOLUTIONS
Capsular hydrostatic pressure (CHP) - ANSWER-- This pressure also opposes
filtration
- Due to the presence of fluid and solutes in Bowman's capsule
- Causes fluid and solutes to be pushed out of the Bowman's capsule and go back to
the glomerulus
Net filtration pressure (NFP) equation - ANSWER-GHP - (GOP + CHP)
Glomerular filtration rate (GFR) - ANSWER-- 125 ml/min
- Definition: the volume of filtrate formed every minute - it is directly related to the net
filtration pressure
Clearance - ANSWER-- A measure of how quickly a substance is removed/cleared
from your blood done either by your kidneys or liver
- For substances handled by the kidneys, it is determined by measuring the amount
of that substance in your blood and your urine over a 24 hour period
Determining GFR by measuring clearance - ANSWER-- If you measure the
clearance of a substance that is removed from the blood only by filtration and not by
reabsorption or secretion
- The best substances to use is inulin but it is only used experimentally, not clinically
What substance do they used clinically to determine someone's GFR? - ANSWER--
Creatinine
- Creatinine is filtered and not reabsoprbed and only minimally secreted so the
clearance of creatinine is about equal to GFR
- Advantage of using this: normal product secreted by a person so you don't have to
give it to them, just collect and measure the blood
Why is it important that GFR is regulated? (Renal autoregulation) - ANSWER-It must
stay at 125 ml/min because the rate or reabsorption depends on the rate of filtration
What happens if GFR goes below normal? - ANSWER-Everything moves through
the nephron so slowly that you have time to reabsorb more than usual and you end
up saving waste products in the blood
What happens if GFR goes above normal? - ANSWER-Everything rushes through
the nephron so quickly that you don't have time to reabsorb and you end up losing
substances in the urine that you want to keep
How do the kidneys keep GFR within a normal range? - ANSWER-If the GFR is not
normal, it can be brought back to normal by changing the diameter of the afferent
,arteriole which alters the volume of blood coming to the afferent arteriole and the
glomerulus
Parameters monitor in renal autoregulation - ANSWER-- Blood pressure: the
pressure as it flows through the afferent arterioles because this affects the
glomerular hydrostatic pressure, the main pressure that causes filtration and affects
GFR
- Tubular osmolarity: concentration of the filtrate as it flows through the distal
convoluted tubules
Response to increased BP or increased osmolarity - ANSWER-- This means GFR is
high
- Constriction of the afferent arteriole which will decrease blood volume and get GFR
down to normal
Response to decreased BP or decreased osmolarity - ANSWER-- This means GFR
is low
- Dilation of the afferent arteriole to increase the blood volume and get GFR up to
normal
Kidneys also work to fix a low ______________________ - ANSWER-systemic BP
Renin-Angiotensin-Aldosterone System - ANSWER-Works to fix a low systemic BP
(think of separately as the renal autoregulation)
Renin - ANSWER-- Produced by specialized cells of the afferent arteriole (called
juxtaglomerular (JG) cells)
- Released when BP is low
- Converts angiotensinogen to angiotensin I which then gets converted to
angiotensin II by ACE
Angiotensin II - ANSWER-- Causes vasoconstriction which increased BP
- Causes release of aldosterone
Aldosterone - ANSWER-Causes Na+ and water reabsorption (saves them) which
causes an increase in blood volume and thereby increases BP
What effect does the sympathetic nervous system have on the renal system? -
ANSWER-- These occur when BP is low
- Constriction of afferent arterioles: causes decreased urine formation so the water
remains in the blood and increases BP
- Increased renin secretion: acts to increase BP
What is involved in reabsorption? - ANSWER-- Proximal convoluted tubule
- Nutrients
- Excretion by lack of reabsorptive mechanism
- Reabsoption of sodium and water
- Collecting duct
, What are the special capillaries that run parallel to the loop of Henle on some
nephrons? - ANSWER-Vasa recta
What are the three processes involved in making urine? - ANSWER-- Filtration
- Reabsorption
- Secretion
Filtration - ANSWER-- Fluid and solutes leave the blood of the glomerulus and enter
into the renal tubule at the Bowman's capsule
- This is due to a pressure gradient
- It is a relatively nonspecific process
- Anything that is small enough to get through the holes in the glomerulus will be
present in the filtrated, and that includes a lot of stuff you do not want to lose from
the body
Reabsorption - ANSWER-Substances are taken out of the filtrate at the proximal
convoluted tubule and put back into the blood of the peritubular capillaries
Secretion - ANSWER-Substances/wastes are taken out of the blood in the
peritubular capillaries, put into the filtrate, and will come out in the urine
Glomerular membrane - ANSWER-- The glomeruli are tufts of capillaries present in
the cortex of the kidney
- Since they are capillaries, blood is flowing through them
- Unique in 2 ways: they have a fenestrated endothelium (has holes in it) and they
are both fed and drained by arterioles (usually the arteriole only brings blood)
What does the filtration require? - ANSWER-A filter and a pressure gradient
What do the fenestrations provide? - ANSWER-The filter
Where does the pressure gradient come from? - ANSWER-- The fact that the
glomeruli are both fed and drained by arterioles
- Arterioles are high pressure vessles so a high pressure coming in (via afferent
arteriole) and high pressure leaving (via efferent arteriole)
Is pressure higher going in or out of the glomerulus? Why? - ANSWER-Afferent
arterioles have a larger diameter than efferent aterioles so there is a higher pressure
coming into the glomerulus (afferent) than leaving it (efferent)
Three filtration pressures at work at the glomerulus - ANSWER-- Glomerular
hydrostatic pressure (GHP)
- Glomeruluar Osmotic Pressure (GOP)
- Capsular hydrostatic pressure (CHP)
Glomerular hydrostatic pressure (GHP) - ANSWER-- Main pressure pushing for
filtration
- Due to the volume of blood in the glomerulus and the blood pressure in the
glomerulus (GHP = BV x BP)
