P1
Which of the following is TRUE about how water is handled by the nephron?
Water is filtered out of glomerular capillaries by bulk flow.
Which would occur as a result of a decrease in the total body content of Na+?
a decrease in plasma volume, which induces a decrease in GFR and an increase in Na+ reabsorption rate
Which of the following drugs is least likely to decrease blood pressure?
a drug that enhances the activity of angiotensin-converting enzyme
A man with hypertension takes a diuretic that is not potassium-sparing, and he does not increase his ingestion of potassium. Which of the following side-effects would the drug be most likely to cause?
cardiac arrhythmia
Which of the following would be most likely to increase GFR?
constricting efferent arterioles
What is the rate-limiting (regulated) step for stimulating the secretion of aldosterone?
conversion of angiotensinogen to angiotensin I in the blood
After prolonged exertion in a hot climate, baroreceptors would ________ firing, leading to ________ secretion of ________ and thus ________ renal reabsorption of ________.
decrease; increased; vasopressin; increased; water
Which of the following would cause a decrease in the excretion of Na+ and water?
decreased atrial natriuretic peptide secretion
Which would you observe in a person experiencing metabolic acidosis?
decreased urinary pH
Which of the following types of drugs would inhibit spontaneous emptying of the bladder (incontinence)?
drugs that block the effects of parasympathetic neurons on the detrusor muscle
The amount of a substance that is excreted in the urine is equal to the amount that is ________ plus the amount that is ________ minus the amount that is ________
filtered; secreted; reabsorbed
All of the following substances are present in proximal tubular fluid in the kidney, but which one is NOT normally present in urine?
glucose
Which one of the following substances is LEAST dependent on the kidney for regulation of its plasma concentration?
glucose
Where do Na+/K+ ATPase pumps play an active role in reabsorbing Na+?
in the basolateral membrane of cells of the cortical collecting duct
If a patient with pulmonary disease began to hypoventilate, how would plasma levels of [H+], HCO3-, and PCO2 be changed, compared to normal?
increased [H ], increased PCO2, and increased [HCO3 ]
Which of these would result in an increase in the osmolarity of urine?
increased levels of vasopressin in the plasma
Which stimulates vasopressin secretion?
increased plasma osmolarity
Which would result in the greatest stimulation of aldosterone secretion?
increasing plasma K+ concentration and increasing plasma angiotensin II concentration
How would the kidneys respond to hypoventilation?
increasing secretion of H and increasing production of new HCO3
Compared to the normal plasma osmolarity, the tubular fluid is ________ as it enters Bowman's space, ________ at the beginning of the loop of Henle, ________ at the tip of the loop, and ________ at the beginning of the distal convoluted tubule.
isosmotic; isosmotic; hyperosmotic; hypoosmotic
Which of the following symptoms would a patient with a deficiency of parathyroid hormone be most likely to experience?
low plasma calcium levels and increased muscular excitability
Which of the following is least likely to be filtered into Bowman's capsule in a normal, healthy person?
plasma protein
What region of the nephron reabsorbs about two-thirds of filtered Na+ and Cl-?
proximal convoluted tubule
Most of the reabsorption of filtered calcium is unregulated and occurs in the ________, but an additional amount can be reabsorbed in the _________, depending on the plasma concentration of parathyroid hormone.
proximal convoluted tubule, distal convoluted tubule
In the presence of aldosterone, which nephron region reabsorbs the greatest fraction of the filtered Na+?
proximal tubule
Which is NOT a function of the kidneys in maintaining homeostasis?
regulation of blood glucose concentration
Which of these directly results from hypoventilation?
respiratory acidosis
Which would result from ingesting a large amount of salt?
secretion of atrial natriuretic factor would increase
In which region of the nephron does the fractional reabsorption of water vary the most in response to variation in the state of hydration?
the collecting duct
In what segment of the nephron is the greatest fraction of filtered water reabsorbed?
the proximal tubule
Which of the following describes tubular reabsorption in the kidney?
transepithelial transport from the lumen of the tubule into renal interstitial fluid
The loss of 0.5 L of sweat would stimulate a greater increase in vasopressin secretion than the loss of an equal amount of blood plasma over the same period of time. This statement is:
true, because sweat is hypoosmotic to plasma.
Water and NaCl reabsorbed from the loop of Henle directly reenter what blood vessels?
vasa recta
Which of these is deficient in the disease, diabetes insipidus?
vasopressin
How does the renal countercurrent multiplier mechanism allow the creation of a concentrated urine?
By concentrating NaCl in the renal medullary interstitium, it allows water to be reabsorbed from the collecting ducts when vasopressin is present.
Which of the following statements about renal control of blood acid-base balance is TRUE?
Increased metabolism of glutamine by renal tubular cells increases the plasma bicarbonate concentration.
Which correctly describes the composition of the glomerular filtrate?
It is highly similar to plasma, except it does not contain plasma proteins.
Which correctly describes renin?
It is secreted by juxtaglomerular cells in renal afferent arterioles.
Which is TRUE about the juxtaglomerular apparatus?
It is the site of renin secretion.
Which is TRUE about the hormone vasopressin (also known as antidiuretic hormone, ADH)?
It triggers insertion of aquaporins into the apical membranes of collecting duct cells.
Which of the following substances undergo renal tubular secretion?
K+
Which of the following statements regarding renal handling of Na+ is correct?
Na+ is actively reabsorbed in the ascending limb of the loop of Henle.
Which is NOT a transport mechanism typically seen in renal tubular epithelial cells?
Na+-K+ ATPase pumps in the luminal membrane of proximal tubule epithelial cells that move Na+ from inside the cell into the tubule and K+ from the tubule lumen into the cell
Which of the following statements regarding Ca2+ homeostasis is TRUE?
Parathyroid hormone directly stimulates Ca2+ reabsorption by the kidneys.
Which of the following most accurately describes the renal transport of Na+?
Primary active transport of Na+ allows for secondary active transport of glucose and H+ in the proximal tubule.
Which is TRUE regarding renal tubular reabsorption?
Reabsorption of glucose saturates at a maximum transport rate.
At the tip of the loop of Henle, the osmolarity of the tubular fluid is more than four times greater than that of the glomerular filtrate when a person is in an antidiuretic state.
T
Both Na+ and Cl- freely filter from the glomerular capillaries into Bowman's space, with no secretion along the renal tubule.
T
Cardiac arrhythmias may be a clinical sign of either K+ depletion or excess.
T
In healthy individuals, the amount of glucose present in urine will be virtually zero because the amount of glucose reabsorption from the filtrate back into the blood prevents excretion.
T
Increasing the GFR tends to increase the excretion rate of sodium.
T
Most of the body's water is located inside cells, whereas most of the body's Na+ is in the interstitial fluid and plasma.
T
The anatomic arrangement of juxtamedullary nephrons in the kidneys is such that the glomerulus, proximal tubule, and distal convoluted tubule are in the renal cortex, while the loop of Henle and collecting ducts lie mainly in the renal medulla.
T
The countercurrent mechanism of the kidney enables the formation of hypertonic urine.
T
The filtered load of water in an average person is approximately 180 L/day.
T
The fluid entering the distal convoluted tubule is hypoosmotic with respect to plasma.
T
The reabsorption of water in the nephron is accomplished as it follows the osmotic gradient created by Na+ reabsorption.
T
The spinal reflex for micturition involves stretch receptors in the wall of the bladder that send messages about distension to sympathetic, parasympathetic, and motor neurons in the spinal cord.
T
The total solute concentration in the extracellular fluid is mainly dependent upon the concentration of Na+ in the extracellular fluid.
T
Total-body balance of water and Na+ is largely maintained by regulating urinary loss of these substances.
T
Unlike Na+, K+ is secreted by the nephron tubules.
T
Unlike the renal cortical interstitial fluid, the interstitial fluid of the medulla is hyperosmotic.
T
Voluntary control of micturition involves controlling somatic motor input to the muscles of the external urethral sphincter.
T
Water absorption from the proximal tubule is mainly driven by the active reabsorption of Na+.
T
In the condition diabetes mellitus, why does glucose appear in the urine?
The filtered load of glucose becomes greater than the tubular maximum for its reabsorption.
Which is NOT true about the countercurrent multiplier system of the kidney?
The fraction of filtered NaCl reabsorbed from the ascending limb equals the fraction of filtered water reabsorbed from the descending limb.
Which of the following statements concerning the process of glomerular filtration is correct?
The hydrostatic pressure in Bowman's space opposes filtration.
Which would occur if a person lost the ability to synthesize vasopressin?
The urine would become hypoosmotic compared to plasma.
Which of the following does NOT correctly describe kidney function?
They produce urine of a constant composition at all times, in order to maintain homeostasis of extracellular fluid.
Which is true for a man who is in balance for total body water?
He must ingest more water than is lost in the urine.
Which equation is equal to the net glomerular filtration pressure?
= hydrostatic pressure in glomerular capillaries - hydrostatic pressure in Bowman's capsule - osmotic force due to proteins in plasma
Which of the following most accurately describes the actions of aldosterone?
Aldosterone increases Na+ reabsorption and K+ secretion in the cortical collecting ducts.
A consequence of lack of vasopressin is excretion of sugar in the urine, which occurs in the condition diabetes mellitus.
F
A fall in the osmolarity of the blood supplying the hypothalamus is a powerful stimulus for thirst.
F
A person lacking vasopressin would have to drink 180 L of water per day to make up for the water lost in the urine.
F
A stimulus for increased aldosterone secretion is decreased plasma K+ concentration.
F
A substance that interferes with the active transport of Na+ in the cortical collecting ducts will also interfere with K+ reabsorption.
F
Atrial distension is a stimulus for the secretion of atrial natriuretic factor, which stimulates the reabsorption of sodium by the kidneys.
F
Because fluid loss as sweat is isoosmotic, the baroreceptor reflexes are more important than osmoreceptor activity in restoring extracellular fluid volume after sweating.
F
Following hemorrhage, vasopressin secretion increases because of increased firing of hypothalamic osmoreceptors.
F
If water intake (ingestion) is decreased, the kidney can decrease the amount of water excreted in urine by increasing the amount of water reabsorbed at the renal corpuscle.
F
In the absence of vasopressin, urine is isoosmotic with plasma.
F
In the proximal convoluted tubule the reabsorption of Na+ is unaffected by the presence or absence of other substances such as glucose or H+ in the filtrate.
F
Ingestion of large amounts of K+ triggers reflexes to limit the amount of K+ reabsorbed by the cortical collecting ducts.
F
Large amounts of protein in a person's urine indicate that the person is eating a high- protein diet.
F
Only substances that are filtered by the kidneys can be excreted by them.
F
Regulation of extracellular K+ is not critical to body function because only about 2% of the total-body K+ is in the extracellular fluid.
F
Stimuli that cause increased Na+ reabsorption decrease K+ secretion.
F
The distal convoluted tubules drain directly into the renal pelvis, which in turn drains into the ureter, a tube that carries urine to the bladder.
F
The kidneys regulate the plasma concentrations of water, sodium, and glucose.
F
The main force responsible for water reabsorption from the collecting ducts is the low hydrostatic pressure in the surrounding interstitial space.
F
The three basic processes of kidney function are filtration from the glomerulus into Bowman's capsule, secretion from the tubule into the peritubular capillaries, and reabsorption from the capillaries into the tubular lumen.
F
The walls of the ascending limb of the loop of Henle are freely permeable to water.
F
Water, sodium, and glucose all undergo tubular reabsorption, but urea does not.
F
Which correctly describes a basic renal process?
Fluid moves by bulk flow from glomerular capillaries into Bowman's space.
Which of the following organs is the main site of aldosterone secretion?
adrenal glands
Constriction of the ________ decreases hydrostatic pressure in _________.
afferent arterioles, glomerular capillaries
Which would NOT be caused by a decrease in plasma Ca2+ levels in an otherwise normal person?
an increase in bone density
What change in renal regulation of H+ would help compensate for a metabolic acidosis?
an increase in the production of new plasma HCO3
When blood Ca2+ levels fall below normal, in what ways do the kidneys help restore them toward normal?
by increasing 1,25-dihydroxyvitamin D3 formation, decreasing tubular phosphate reabsorption, and increasing tubular Ca2+ reabsorption