Question 1

Which stimulates vasopressin secretion?

Accepted Answer

Vasopressin secretion is stimulated by an increase in plasma osmolarity, which indicates that the body needs to conserve water. Vasopressin helps to increase water reabsorption in the kidneys, leading to a decrease in urine output and an increase in plasma volume. Increased plasma volume (choice B) would actually lead to a decrease in vasopressin secretion because the body does not need to conserve water in this situation. Ingestion of alcohol (choice C) can inhibit vasopressin secretion, leading to increased urine output and dehydration. Decreased aldosterone secretion (choice D) would not have a direct effect on vasopressin secretion, as these hormones have different functions in regulating electrolyte and fluid balance. Increased pressure in afferent arterioles (choice E) may have an effect on renal blood flow and glomerular filtration rate, but it is not directly related to the regulation of vasopressin secretion.

Question 2

If a patient with pulmonary disease began to hypoventilate,how would plasma levels of [H⁺],HCO₃⁻,and PCO₂ be changed,compared to normal?

Accepted Answer

Hypoventilation leads to an accumulation of CO₂ in the blood, which increases PCO₂. This in turn increases the concentration of H⁺ (lowering pH) and stimulates the renal compensation mechanism, which retains HCO₃⁻ to buffer the increased acidity, thus increasing [HCO₃⁻].

Question 3

Which of the following would cause a decrease in the excretion of Na⁺ and water?

Accepted Answer

Decreased atrial natriuretic peptide (ANP) secretion would lead to decreased excretion of Na⁺ and water because ANP promotes natriuresis and diuresis.

Question 4

Which of the following statements about renal control of blood acid-base balance is TRUE?

Accepted Answer

Increased metabolism of glutamine by renal tubular cells generates new bicarbonate ions, which can be reabsorbed into plasma and increase plasma bicarbonate concentration. Option B is incorrect because excretion of hydrogen bound to phosphate buffers decreases plasma phosphate concentration, not bicarbonate concentration. Option C is incorrect because H⁺ that binds to filtered bicarbonate in the tubular fluid is reabsorbed by the tubular cells and helps generate new bicarbonate ions, rather than being excreted in the urine. Option D is incorrect because when hypoventilation occurs, the kidneys compensate by increasing, not reducing, glutamine metabolism. Option E is incorrect because the kidneys compensate for a metabolic alkalosis by excreting bicarbonate in the urine, not increasing CO₂ production.

Question 5

Following a series of high-intensity training runs,lactic acid was generated by the leg muscles and is now circulating in the blood.Which of the following is likely to occur?

Accepted Answer

Lactic acid is an acid that can contribute hydrogen ions to the blood. In order to maintain acid-base balance (pH) in the blood, the kidneys will excrete more hydrogen ions and reabsorb more bicarbonate ions during periods of increased acidity. This leads to a decrease in urinary pH, as more hydrogen ions are excreted. Therefore, the correct answer is D, decreased urinary pH.

Question 6

Which would NOT be caused by a decrease in plasma Ca²⁺ levels in an otherwise normal person?

Accepted Answer

A decrease in plasma Ca²⁺ levels would typically trigger a cascade of responses to increase Ca²⁺ levels in the blood, including an increase in parathyroid hormone levels and 1,25-dihydroxyvitamin D₃ levels, as well as an increase in nerve and muscle excitability. However, a decrease in plasma Ca²⁺ levels would not lead to an increase in bone density. In fact, chronic low Ca²⁺ levels can lead to decreased bone density and osteoporosis.

Question 7

In the presence of aldosterone,which nephron region reabsorbs the greatest fraction of the filtered Na⁺?

Accepted Answer

The proximal tubule reabsorbs the greatest fraction of the filtered Na⁺, approximately 65-70%, even though aldosterone primarily acts on the distal convoluted tubule and cortical collecting duct to increase Na⁺ reabsorption.

Question 8

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?

Accepted Answer

The diuretic would cause increased excretion of potassium, leading to hypokalemia. Hypokalemia can lead to cardiac arrhythmias, which can be dangerous for a patient with hypertension. Choice A is incorrect because a diuretic would actually decrease blood volume. Choice B is incorrect because depolarized neuronal cell membranes are not a side effect of a potassium-wasting diuretic. Choice C is incorrect because hyperkalemia is not a side effect but rather the opposite of what would occur due to potassium-wasting diuretics.

Question 9

Following an intense workout your clothes are drenched in sweat.You estimate you lost at least 0.5 L of sweat.Your (similarly sized)friend skipped her workout to donate blood and you found out she donated 0.5 L of plasma.After these activities,which of you will have a greater increase in vasopressin secretion and why?

Accepted Answer

Sweat is generally hypoosmotic compared to plasma, meaning it has a lower concentration of solutes. When you lose hypoosmotic fluid through sweating, your body's remaining extracellular fluid becomes more concentrated. This increase in osmolality stimulates the secretion of vasopressin (also known as antidiuretic hormone or ADH) to promote water reabsorption in the kidneys and help restore fluid balance. In contrast, donating blood removes a volume of isosmotic fluid (plasma), which does not immediately alter the osmolality of the body fluids. Therefore, the loss of hypoosmotic sweat would lead to a greater increase in vasopressin secretion compared to the isosmotic loss of plasma through blood donation.

Question 10

Which of the following most accurately describes the actions of aldosterone?

Accepted Answer

Aldosterone increases Na⁺ reabsorption and K⁺ secretion in the cortical collecting ducts of the nephron. It does not affect the proximal tubule. This hormone works to increase blood volume and pressure by causing the kidneys to reabsorb more sodium ions and excrete more potassium ions. This action takes place primarily in the cortical collecting ducts of the kidney, which is where aldosterone binds to and activates specific receptors on the cells of this duct. Thus, choice E is the most accurate description of the actions of aldosterone.

Question 11

You are the CEO of a drug company where you've asked five teams of scientists to generate new drugs to decrease blood pressure.You can only send four of the drugs to market.Which of these drugs is least likely to decrease blood pressure and can be eliminated from potential development?

Accepted Answer

Angiotensin-converting enzyme (ACE) inhibitors are commonly used medications for hypertension because they decrease the activity of angiotensin II, a potent vasoconstrictor. Therefore, enhancing the activity of ACE (as with drug D) would be counterproductive in decreasing blood pressure.

Question 12

Following a few months of noticeably high urine volume,Stephanie's doctor diagnosed her with diabetes insipidus and prescribed her desmopressin,which is a synthetic drug form of vasopressin.A few weeks later,Stephanie accidentally takes two doses instead of one.On that day,what is Stephanie likely to experience?

Accepted Answer

The answer of Following a few months of noticeably high...

Question 13

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.

Accepted Answer

The majority of calcium reabsorption occurs in the proximal convoluted tubule in an unregulated manner, while additional regulated reabsorption, influenced by parathyroid hormone levels, occurs in the distal convoluted tubule.

Question 14

When blood Ca²⁺ levels fall below normal,in what ways do the kidneys help restore them toward normal?

Accepted Answer

When blood Ca²⁺ levels fall below normal, the kidneys help restore them toward normal by increasing the formation of 1,25-dihydroxyvitamin D₃, which enhances the absorption of calcium in the intestines. The kidneys also decrease the reabsorption of phosphate in the tubules, as phosphate tends to inhibit calcium uptake in the intestines. Additionally, the kidneys increase the reabsorption of calcium in the tubules, thus conserving calcium in the body. This is the best choice among the given options.

Question 15

Which of the following statements regarding Ca²⁺ homeostasis is TRUE?

Accepted Answer

Parathyroid hormone directly stimulates Ca²⁺ reabsorption by the kidneys.

Question 16

How would the kidneys respond to hypoventilation?

Accepted Answer

Hypoventilation leads to an accumulation of CO₂ in the blood, causing respiratory acidosis. The kidneys respond by increasing the secretion of H⁺ to remove excess acid and by increasing the production of new bicarbonate (HCO₃⁻) to buffer the increased acidity.

Question 17

Which would result in the greatest stimulation of aldosterone secretion?

Accepted Answer

Increasing plasma K⁺ concentration and increasing plasma angiotensin II concentration both stimulate the secretion of aldosterone. Plasma K⁺ concentration is the most important factor that regulates aldosterone secretion, and high levels of K⁺ in the blood would activate aldosterone secretion. Angiotensin II also stimulates aldosterone secretion by activating the renin-angiotensin-aldosterone system. The other options either decrease aldosterone secretion (A and E) or are not as potent stimuli as D.

Question 18

Andres has a parathyroid hormone deficiency.He first approached the doctor because he was experiencing ________ and the early blood tests found that he had ________.

Accepted Answer

Parathyroid hormone helps regulate calcium levels in the blood. A deficiency in this hormone would lead to low plasma calcium levels, which in turn increases neuromuscular excitability due to the lowered threshold for nerve and muscle activation.

Question 19

You are an EMT and arrive at the scene of an opioid overdose.The overdose victim is breathing extremely slowly and shallowly.When you arrive at the ER,you report that the medical team should watch out for signs of

Accepted Answer

The shallow and slow breathing pattern of the overdose victim indicates that they are likely experiencing respiratory depression which can lead to a buildup of carbon dioxide in the body, ultimately leading to respiratory acidosis. Therefore, the medical team should watch out for signs of respiratory acidosis as a potential complication of the overdose.

Question 20

After prolonged exertion in a hot climate,baroreceptors would ________ firing,leading to ________ secretion of ________ and thus ________ renal reabsorption of ________.

Accepted Answer

After prolonged exertion in a hot climate, baroreceptors would decrease firing due to decreased blood volume, leading to increased secretion of vasopressin and thus increased renal reabsorption of water. This helps to rehydrate the body and maintain blood pressure. Renin and Na⁺ reabsorption levels are not affected by baroreceptor firing in this scenario.

Quiz 14: The Kidneys and Regulation of Water and Inorganic Ions

Which stimulates vasopressin secretion?

If a patient with pulmonary disease began to hypoventilate,how would plasma levels of [H⁺],HCO₃⁻,and PCO₂ be changed,compared to normal?

Which of the following would cause a decrease in the excretion of Na⁺ and water?

Which of the following statements about renal control of blood acid-base balance is TRUE?

Following a series of high-intensity training runs,lactic acid was generated by the leg muscles and is now circulating in the blood.Which of the following is likely to occur?

Which would NOT be caused by a decrease in plasma Ca²⁺ levels in an otherwise normal person?

In the presence of aldosterone,which nephron region reabsorbs the greatest fraction of the filtered Na⁺?

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?