A&P II Ch. 24 Urinary System
The arteriole that delivers blood to the glomerulus is the __________.
afferent arteriole *The afferent arteriole is located between the interlobular artery and the glomerulus
Which of the following substances is not normally found in filtrate?
blood cells and large particles *Yes, both blood cells and large particles, such as proteins, are not allowed to filter through a healthy glomerular membrane
In which part of the renal tubule does aldosterone primarily target?
Distal tubule
Reabsorption moves water and solutes:
from filtrate to blood *Reabsorption reclaims substances from filtrate back to blood.
The functional unit of the kidney is the ___________.
nephron
Which of the following hormones causes sodium reabsorption in the distal tubule?
Aldosterone *Aldosterone from the adrenal cortex stimulates Na (and indirectly water) reabsorption and K secretion.
The kidneys __________________.
All these choices are correct. excrete nitrogenous wastes regulate acid-base balance produce renin maintain water balance
The amount of filtrate formed by both kidneys in 1 minute is defined as the __________.
GFR *The glomerular filtration rate is about 125 ml/min.
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.
25 mm Hg *Yes, 60 - (25 + 10) = 25 mm Hg. The two pressures that oppose filtration must be subtracted from the force favoring filtration.
Which of the following forces drives filtration?
Glomerular hydrostatic pressure (GHP) *Glomerular hydrostatic pressure (GHP) is the force with which blood pushes on the walls of glomerular capillaries and it drives filtration.
An increase in blood pressure will cause an increase in _______.
Glomerular hydrostatic pressure (GHP) *The GHP is largely determined by the systemic blood pressure.
Which of the following transporters in the luminal membrane results in secretion?
Na+-H+ countertransport *Yes, because this is a countertransporter, Na+ is transported into the cell and H+ is transported out of the cell into the lumen.
In what part of the renal tubule does most reabsorption of substances occur?
Proximal tubule
What determines whether a substance can move through the filtration membrane?
Size of the substance
Metabolic acidosis is a condition characterized by a decrease in blood pH below pH 7.35. What effect will this condition have in the urine?
The pH of urine would decrease.
Which of the following will result in a decrease of GFR?
constriction of the afferent arteriole *Constriction of the afferent arteriole and dilation of the efferent arteriole are the mechanisms of myogenic autoregulation, which will cause a decrease in GFR
Angiotensin II promotes:
constriction of the efferent arteriole *Constriction of the efferent arteriole increases GFR and ensures filtration will continue even when systemic blood pressure is low.
Filtration happens at the:
glomerulus *Filtration happens as blood flows through the glomerular capillaries.
The thick ascending limb of the nephron loop is mostly permeable to:
ions, such as Na and Cl
If the osmotic pressure in the glomerular capillaries increased from 28 mm Hg to 35 mm Hg, would net filtration increase or decrease?
net filtration would decrease *Yes, because osmotic pressure opposes filtration, increasing osmotic pressure would decrease net filtration.
The distal tubule is a site fo
reabsorption and secretion *Facultative reabsorption and secretion take place in the distal tubule of the nephron.
Released by the juxtaglomerular (JG) cells in response to a decrease in systemic blood pressure
renin
The thin descending limb of the nephron loop is freely permeable to __________.
water
During filtration, ___________ pressure forces water and solutes small enough to pass through the filtration membrane into the capsular space.
hydrostatic
What is the primary driving force (pressure) that produces glomerular filtration?
hydrostatic pressure of blood (blood pressure) *Yes, the hydrostatic pressure of blood forces fluid out of the glomerular capillaries.
Most nutrients, such as glucose, are reabsorbed in the __________.
proximal tubule *The proximal tubule is responsible for the reabsorption of nearly 100% of nutrients such as glucose, amino acids, and other organic substances.
Returning fluid and solutes from filtrate to blood happens via __________.
tubular reabsorption *Tubular reabsorption transports nutrients back into the blood. The nutrients were filtered due to their small size, allowing them to go through the filtration membrane.
What structure is located between the renal corpuscle and the nephron loop (loop of Henle)?
Proximal tubule
Which of the following functions is NOT one of the functions of the urinary system?
Regulation of leukocyte production *The urinary system is involved in the regulation of erythrocyte production, because the kidneys release the hormone erythropoietin, but it does not regulate production of leukocytes.
What affect would high blood pressure medication have on the GFR?
The GFR would temporarily increase due to dilation of the renal arteries and afferent arterioles. *Blood pressure medication will increase the GFR temporarily by increasing the glomerular hydrostatic pressure due to the dilation of renal arteries and afferent arterioles.
During reabsorption of water in the proximal convoluted tubule, what causes water to diffuse from the lumen into the interstitial space?
an increase in the osmolarity of the interstitium
Promotes the release of aldosterone by the adrenal glands
angiotensin-II (A-II)
Promotes vasoconstriction of efferent arterioles and systemic blood vessels
angiotensin-II (A-II)
Inserts aquaporins to increase water reabsorption by cells in the late distal tubule and cortical collecting duct
antidiuretic hormone (ADH)
Triggers urinary excretion of sodium ions
atrial natriuretic peptide (ANP)
The filtration membrane is created by the ________ and ________.
glomerulus; podocytes
If there was no reabsorption in the proximal tubule, which of the following useful substances would be lost in urine:
glucose *Glucose and other nutrients are rapidly reabsorbed in the proximal tubule. If not, they would be lost in the urine.
Which of the following will cause an increase in GHP and GFR?
Dilation of the afferent arteriole *Vasodilation of the afferent arteriole will allow more blood to get into the glomerular capillaries, therefore increasing GHP and GFR.
Secretion happens via:
Facilitated transport only *Pumps or carriers are always required for secretion.
Which of the following solutes are not able to pass through the filtration membrane in a healthy kidney?
albumin *Albumin is a plasma protein and is too large to pass through the filtration membrane.
Converts angiotensin-I (A-I) to active angiotensin-II (A-II)
angiotensin converting enzyme (ACE)
Which of the following is NOT a component of the filtration membrane?
epithelial cells of the glomerular capsule *Filtrate collects inside the glomerular capsule, but the capsule itself is not part of the filtration membrane.
If the osmotic pressure in the glomerular capillaries increased from 28 mmHg to 35 mmHg due to dehydration, would net filtration increase or decrease?
Net filtration would decrease
Which of the following solutes will NOT pass across the filtration membrane?
Plasma proteins *Plasma proteins, like albumin, are too large to pass through the filtration membrane.
When the macula densa detects an increase in NaCl concentration in the renal filtrate, what happens to the glomerular filtration rate (GFR)?
GFR decreases
The Net Filtration Pressure (NFP) is equal to:
GHP - (GCOP + CHP) *NFP is equal to the force that drives filtration (GHP) minus the combination of forces that oppose filtration (CHP + GCOP)
Which of the following events is the first step of urine formation?
Glomerular filtration
Which of the following would be a "potassium sparing diuretic," a drug that causes an increase in water loss, and a decrease in potassium loss in the kidneys?
a drug that blocks the effect of aldosterone •If Aldosterone is inhibited, there will be less Na reabsorption, less water reabsorption, and less potassium secretion. Therefore, there will be increased water loss in urine, while potassium is "spared" and remains in blood.
The most common type of nephrons, which have a relatively short nephron loop that does NOT extend deep into the medulla, are called __________ nephrons.
cortical *The renal corpuscles of cortical nephrons are situated in the outer renal cortex, and t. They have very short nephron loops that either just dip into the superficial part of the renal medulla, or never leave the cortex.
The hormone ANP causes an __________.
increase in GFR *ANP increases the GFR. High GFR leads to more fluid loss and therefore decreases blood volume and effectively lowers blood pressure.
Which of the following is not a factor that increases blood pressure?
increased parasympathetic activity *Elevated parasympathetic activity decreases peripheral resistance, decreases cardiac output, and decreases blood volume. These all lower blood pressure.
Which of the following cells or organs releases renin?
juxtaglomerular cells *The juxtaglomerular cells in the wall of the afferent arteriole release renin in response to low blood pressure.
Which of the following is NOT a component of the urinary tract?
kidneys *The kidneys are the organs that produce urine. The urinary tract stores urine and eliminates it. The kidneys are not part of the urinary tract.
A decrease in GFR will cause __________.
lower Na and Cl ion concentration in the distal tubule *Because less filtrate moves slower through the tubule and allows for more reabsorption, fewer sodium and chloride ions are delivered to the macula densa cells of the distal tubule. This activates the tubuloglomerular feedback mechanism, resulting in an increased GFR
What is the limiting factor for the reabsorption of most actively transported solutes in the proximal tubule?
number of transport carriers in the luminal membrane *Yes, the number of carriers is the rate-limiting factor. For example, in Diabetes Mellitus, plasma glucose levels are very high, and the sodium-glucose transporter cannot transport (reabsorb) all the glucose passing through the proximal tubule. Glucose is therefore found in the urine.
Which of the following is controlled voluntarily?
opening of the external urethral sphincter
Reabsorption in which substances pass between adjacent tubular cells is called:
paracellular *The paracellular route of reabsorption involves passage of substances between adjacent tubular cells.
Which substance would be found in higher concentration if the membrane were damaged?
protein *Yes, large proteins are not normally filtered by a healthy glomerular membrane.
The tight coiling and looping of the glomerular capillaries is functionally important, because it:
provides increased surface area for filtration *The combined area of all glomerular capillaries in one kidney combined is about 65 square feet. This large surface area makes filtration a very efficient process.
The active transport of which ion out of proximal convoluted tubule cells causes the reabsorption of both water and solutes?
sodium *Yes, the active transport of sodium out of the cell, across the basolateral membrane into the interstitium, provides the driving force for reabsorption of both water and solutes.
Which of the following is NOT part of the filtration membrane?
squamous epithelial cells of the glomerular capsule *The parietal layer of the glomerular capsule is not part of the filtration membrane. Instead it forms the chamber in which filtrate is collected.
The micturition reflex is initiated by __________
stretch receptors in the wall of the blade *The stretch receptors send a signal via sensory afferent fibers to the sacral portion of the spinal cord.
The urinary tract would not function as well if it was composed of simple squamous epithelium because:
the simple squamous epithelium is extremely thin, would not provide adequate protection, and be more prone to tearing
The decreased intracellular concentration of sodium in tubular cells during active transport is caused by which of the following mechanisms?
the sodium-potassium ATPase pump in the basolateral membrane *Yes, this pump moves sodium out of the cell into the interstitium, thus decreasing intracellular sodium.
Recall that the sympathetic nervous system causes activation of Angiotensin II. With this knowledge, how would the sympathetic nervous system be affected by a treatment for high blood pressure?
the sympathetic nervous system would be inhibited *If you prevent the sympathetic branch from working, there will be less activation of Angiotensin II and therefore blood pressure will stay low. Indeed one of the newest treatments for hypertension involves surgery to interfere with sympathetic innervation of the kidneys. Similarly, a common drug prescribed to patients with high blood pressure inhibits components of the RAAS system.
Most solutes that are reabsorbed in the proximal convoluted tubule use which of the following pathways?
transcellular *Yes, most substances are reabsorbed first through the luminal and then through the basolateral membranes of the proximal convoluted tubule.
Which of the following is a normal property of urine?
translucent
Consuming alcohol inhibits the release of ADH. As a result __________.
urine volume will increase *If ADH is reduced, there will be less water reabsorption, therefore more water will remain in the filtrate, and therefore more urine will be produced.