PHM 819 Module 4 Exam UPDATED
QUESTIONS AND CORRECT ANSWERS
What is the main excretory route for the majority of drugs? (a) What are the other minor
routes of excretion? (b) - CORRECT ANSWER (a) Renal
(b) Fecal/Hepatic, Pulmonary, Sweat, Tears, Hair, Nails, Eggs, Milk, Saliva
How much of the systemic blood flow is supplied to the kidneys? (a) What does this help
ensure? (b) - CORRECT ANSWER (a) 25%
(b) Ensures the kidneys are continuously exposed to drug
What is the basic functional unit of the kidney? - CORRECT ANSWER Nephron
Renal secretion depends on the balance of what factors? (a) Where are the locations of each
factor? (b) - CORRECT ANSWER Filtration, Secretion, and Reabsorption (a)
(b) Filtration = glomerulus
Secretion = proximal tubule
Reabsorption = distal tubule
Where does the blood enter (a) and exit (b) prior to and after filtration at the glomerulus?
How much of the blood becomes filtrate? (c) - CORRECT ANSWER (a) Afferent
arteriole
(b) Efferent arteriole
(c) 20% (80% distributed to peritubular capillaries)
Describe factors that affect the rate of filtration at the glomerulus - CORRECT
ANSWER -Blood flow (increase flow = increase filtration)
-Extent of plasma-protein binding (only free, unbound drug can bind)
-Charge of chemical (negatively charged drugs cannot be filtered)
-Glomerular Filtration Rate (20% of blood reaching glomerulus actually becomes filtrate)
-Size of chemical (all chemical can be filtered for molecules of up to 5000 daltons in size)
,Why does plasma-protein bound drug affect the rate of filtration? - CORRECT
ANSWER Plama proteins are too large to filter at the glomerulus, so only the free drug
can filter at the glomerulus.
What does it mean if we see plasma protein (such as albumin) in someone's urine? -
CORRECT ANSWER It means that there is renal dysfunction at the glomerulus, as
plasma proteins are normally too large to fit through the glomerulus.
What substances are found in the urine of a healthy person without renal issues? - CORRECT
ANSWER Water, solutes (sodium/chloride, potassium, bicarbonate) amino acids, urea,
creatinine, and other excreted waste products
Why is filtrate production rate different than the production rate of urine? - CORRECT
ANSWER Of the blood that is filtered at the glomerulus, about 20% of it is actually
produced to make filtrate. For the average person with blood flow to kidney at 650 mL/min,
this is 125 mL/min for the GFR. Due to the body wanting to reabsorb as much water as
possible to prevent dehydration, urine production is much smaller (about 1 mL of urine/min).
How is water of excretion in the urine regulated by the body? - CORRECT
ANSWER There are two hormones that help regulate the amount of water excreted via
urine in the body.
Aldosterone acts on the distal tubule to regulate the rate of water excretion (water
reabsorption can be "fine tuned" at the distal tubules)
Anti Diuretic Hormone (ADH) or Vasopressin increases water reabsorption at the collecting
ducts
Describe filtration at the glomerulus. - CORRECT ANSWER It is the structure that
encapsulates the capillaries of the glomerulus where filtration occurs is Bowman's capsule. It
is composed of specialized endothelial cells (podocytes) that have negatively charged foot
processes that wrap around the capillaries (composed of anionic amino acids, sialic acid
residues, and proteoglycans). The fenestrations of the glomerulus capillaries allows filtration
at the podocytes into the Bowman's capsule. Negatively charged chemicals are repelled at the
, podocytes and cannot be filtered across the podocytes. The filtrate that is produced can then
enter the proximal tubule for further secretion/reabsorption of substances to produce urine.
What molecule is most accurately used to determine GFR? - CORRECT
ANSWER Inulin is a carbohydrate that is almost exclusively filtered (no substantial
amount of secretion or reabsorption). The renal clearance of inulin is equal to GFR.
Where does most of chemical secretion into the urine occur? - CORRECT
ANSWER The proximal tubules (movement from the peritubular capillaries to
proximal tubular cells to the tubular lumen).
Why is plasma-protein bound drug not a factor of secretion? (need clarification) - CORRECT
ANSWER The secretion of free drug into the proximal tubules is rapid enough via the
transport mechanisms that it alters the equilibrium between bound drug and free drug so that
even protein-bound drug is cleared (active transport steals drug from protein?)
Describe how so many drugs can be most effectively excreted in urine via secretion? -
CORRECT ANSWER The proximal tubules contain a diversity of non-specific
transporters (facilitated diffusion and active transport) that take advantage between the
similarities of drugs and naturally occuring substances.
What is a downside to the non-specificity of transport proteins of secretion? - CORRECT
ANSWER Drugs taken together may compete for uptake into cell/efflux into urine,
which may lead to adverse events since the drug is not clearing at the expected rate (build up
of toxic levels in the plasma)
What are the four varieties of transporters that are located at the proximal tubule cells? -
CORRECT ANSWER Cation transporters
Anion transporters
Peptide transporters
Nucleoside transporters
How does a chemical get secreted into the urine? - CORRECT ANSWER A chemical
in the peritubular capillaries crosses the basolateral membrane of the proximal tubule cells.
QUESTIONS AND CORRECT ANSWERS
What is the main excretory route for the majority of drugs? (a) What are the other minor
routes of excretion? (b) - CORRECT ANSWER (a) Renal
(b) Fecal/Hepatic, Pulmonary, Sweat, Tears, Hair, Nails, Eggs, Milk, Saliva
How much of the systemic blood flow is supplied to the kidneys? (a) What does this help
ensure? (b) - CORRECT ANSWER (a) 25%
(b) Ensures the kidneys are continuously exposed to drug
What is the basic functional unit of the kidney? - CORRECT ANSWER Nephron
Renal secretion depends on the balance of what factors? (a) Where are the locations of each
factor? (b) - CORRECT ANSWER Filtration, Secretion, and Reabsorption (a)
(b) Filtration = glomerulus
Secretion = proximal tubule
Reabsorption = distal tubule
Where does the blood enter (a) and exit (b) prior to and after filtration at the glomerulus?
How much of the blood becomes filtrate? (c) - CORRECT ANSWER (a) Afferent
arteriole
(b) Efferent arteriole
(c) 20% (80% distributed to peritubular capillaries)
Describe factors that affect the rate of filtration at the glomerulus - CORRECT
ANSWER -Blood flow (increase flow = increase filtration)
-Extent of plasma-protein binding (only free, unbound drug can bind)
-Charge of chemical (negatively charged drugs cannot be filtered)
-Glomerular Filtration Rate (20% of blood reaching glomerulus actually becomes filtrate)
-Size of chemical (all chemical can be filtered for molecules of up to 5000 daltons in size)
,Why does plasma-protein bound drug affect the rate of filtration? - CORRECT
ANSWER Plama proteins are too large to filter at the glomerulus, so only the free drug
can filter at the glomerulus.
What does it mean if we see plasma protein (such as albumin) in someone's urine? -
CORRECT ANSWER It means that there is renal dysfunction at the glomerulus, as
plasma proteins are normally too large to fit through the glomerulus.
What substances are found in the urine of a healthy person without renal issues? - CORRECT
ANSWER Water, solutes (sodium/chloride, potassium, bicarbonate) amino acids, urea,
creatinine, and other excreted waste products
Why is filtrate production rate different than the production rate of urine? - CORRECT
ANSWER Of the blood that is filtered at the glomerulus, about 20% of it is actually
produced to make filtrate. For the average person with blood flow to kidney at 650 mL/min,
this is 125 mL/min for the GFR. Due to the body wanting to reabsorb as much water as
possible to prevent dehydration, urine production is much smaller (about 1 mL of urine/min).
How is water of excretion in the urine regulated by the body? - CORRECT
ANSWER There are two hormones that help regulate the amount of water excreted via
urine in the body.
Aldosterone acts on the distal tubule to regulate the rate of water excretion (water
reabsorption can be "fine tuned" at the distal tubules)
Anti Diuretic Hormone (ADH) or Vasopressin increases water reabsorption at the collecting
ducts
Describe filtration at the glomerulus. - CORRECT ANSWER It is the structure that
encapsulates the capillaries of the glomerulus where filtration occurs is Bowman's capsule. It
is composed of specialized endothelial cells (podocytes) that have negatively charged foot
processes that wrap around the capillaries (composed of anionic amino acids, sialic acid
residues, and proteoglycans). The fenestrations of the glomerulus capillaries allows filtration
at the podocytes into the Bowman's capsule. Negatively charged chemicals are repelled at the
, podocytes and cannot be filtered across the podocytes. The filtrate that is produced can then
enter the proximal tubule for further secretion/reabsorption of substances to produce urine.
What molecule is most accurately used to determine GFR? - CORRECT
ANSWER Inulin is a carbohydrate that is almost exclusively filtered (no substantial
amount of secretion or reabsorption). The renal clearance of inulin is equal to GFR.
Where does most of chemical secretion into the urine occur? - CORRECT
ANSWER The proximal tubules (movement from the peritubular capillaries to
proximal tubular cells to the tubular lumen).
Why is plasma-protein bound drug not a factor of secretion? (need clarification) - CORRECT
ANSWER The secretion of free drug into the proximal tubules is rapid enough via the
transport mechanisms that it alters the equilibrium between bound drug and free drug so that
even protein-bound drug is cleared (active transport steals drug from protein?)
Describe how so many drugs can be most effectively excreted in urine via secretion? -
CORRECT ANSWER The proximal tubules contain a diversity of non-specific
transporters (facilitated diffusion and active transport) that take advantage between the
similarities of drugs and naturally occuring substances.
What is a downside to the non-specificity of transport proteins of secretion? - CORRECT
ANSWER Drugs taken together may compete for uptake into cell/efflux into urine,
which may lead to adverse events since the drug is not clearing at the expected rate (build up
of toxic levels in the plasma)
What are the four varieties of transporters that are located at the proximal tubule cells? -
CORRECT ANSWER Cation transporters
Anion transporters
Peptide transporters
Nucleoside transporters
How does a chemical get secreted into the urine? - CORRECT ANSWER A chemical
in the peritubular capillaries crosses the basolateral membrane of the proximal tubule cells.
