Water makes up a larger percentage of body mass in infants than in older adults.
Correct Answer
True
True. Infants have the highest proportion of body water, and the percentage declines through adulthood into old age, partly as fat and other tissues change.
Category: Fluid Compartments
Question 2
The sodium-potassium pump moves sodium into cells and potassium out of cells.
Correct Answer
False
False. The pump uses ATP to move sodium out of cells and potassium into cells, against their concentration gradients, which keeps sodium high outside and potassium high inside.
Category: Fluid Compartments
Question 3
Insensible water loss occurs through the skin and through air exhaled from the lungs.
Correct Answer
True
True. Insensible losses are water losses a person does not notice, such as evaporation from the skin and water vapor in exhaled breath, separate from visible sweating and urine.
Category: Water Balance
Question 4
Plasma makes up the largest portion of the extracellular fluid.
Correct Answer
False
False. Interstitial fluid, the fluid between cells, is the largest part of the extracellular fluid. Plasma is a smaller fraction confined to blood vessels.
Category: Fluid Compartments
Question 5
Most of the body's daily water output leaves in the urine.
Correct Answer
True
True. Urine is the largest route of water loss, with smaller amounts lost through the skin, the lungs and the feces.
Category: Water Balance
Question 6
Antidiuretic hormone is released into the blood by the anterior pituitary gland.
Correct Answer
False
False. Antidiuretic hormone is made in the hypothalamus and released by the posterior pituitary gland.
Category: Water Balance
Question 7
Angiotensin II stimulates thirst in addition to triggering the release of aldosterone.
Correct Answer
True
True. When blood volume is low, angiotensin II acts on the brain to stimulate thirst and on the adrenal cortex to release aldosterone, and it also constricts blood vessels.
Category: Hormonal Regulation
Question 8
Aldosterone increases the reabsorption of potassium by the kidney tubules.
Correct Answer
False
False. Aldosterone increases sodium reabsorption and increases potassium secretion into the urine, so it lowers blood potassium.
Category: Hormonal Regulation
Question 9
Hyperkalemia can disturb heart rhythm and may lead to cardiac arrest.
Correct Answer
True
True. A high blood potassium level alters the membrane potential of excitable cells, impairing nerve, skeletal muscle and cardiac function, and it can be fatal.
Category: Electrolyte Balance
Question 10
Most of the body's calcium is stored in skeletal muscle.
Correct Answer
False
False. Nearly all of the body's calcium is stored in bone as calcium phosphate salts, which serve as a reservoir for blood calcium.
Category: Electrolyte Balance
Question 11
Most of the body's phosphate is bound in bone and teeth.
Correct Answer
True
True. The majority of phosphate is locked in the calcium phosphate salts of bone and teeth, with the rest in cells as part of ATP, nucleotides and phospholipids.
Category: Electrolyte Balance
Question 12
In hyponatremia, cells shrink as water moves out of them.
Correct Answer
False
False. In hyponatremia the extracellular fluid is too dilute, so water moves into cells and they swell. Swelling of brain cells is what makes severe hyponatremia dangerous.
Category: Electrolyte Balance
Question 13
Carbon dioxide combines with water to form carbonic acid, so retaining carbon dioxide lowers blood pH.
Correct Answer
True
True. Carbonic acid releases hydrogen ions, so any rise in blood carbon dioxide, as when breathing is depressed, makes the blood more acidic.
Category: Respiratory and Renal Control
Question 14
The kidneys correct changes in blood pH faster than the respiratory system does.
Correct Answer
False
False. The respiratory system adjusts pH within minutes by changing the rate of carbon dioxide removal, while renal correction takes hours to days.
Category: Respiratory and Renal Control
Question 15
The phosphate buffer system uses a weak acid form and a weak base form of phosphate to neutralize excess base or acid.
Correct Answer
True
True. Dihydrogen phosphate acts as the weak acid and monohydrogen phosphate as the weak base, so the pair can absorb either added base or added acid. It is especially important inside cells and in urine.
Category: Buffer Systems
Question 16
A blood pH of 7.50 indicates acidosis.
Correct Answer
False
False. Normal blood pH is 7.35 to 7.45, so a pH of 7.50 is above normal and indicates alkalosis. Acidosis is a pH below 7.35.
Category: Acid-Base Disorders
Question 17
Renal tubule cells secrete hydrogen ions into the filtrate in exchange for sodium ions.
Correct Answer
True
True. An antiporter in the apical membrane of tubule cells moves hydrogen ions into the filtrate while bringing sodium back into the cell, which lets the kidney excrete acid and conserve bicarbonate.
Category: Respiratory and Renal Control
Question 18
In respiratory acidosis, the kidneys compensate by excreting more bicarbonate.
Correct Answer
False
False. To compensate for respiratory acidosis, the kidneys conserve bicarbonate and secrete more hydrogen ions, which raises blood pH back toward normal.
Category: Acid-Base Disorders
Question 19
Severe diarrhea can cause metabolic acidosis through the loss of bicarbonate.
Correct Answer
True
True. Intestinal secretions are rich in bicarbonate, so prolonged diarrhea removes base from the body and lowers blood pH.
Category: Acid-Base Disorders
Question 20
Respiratory compensation for metabolic alkalosis involves breathing faster.
Correct Answer
False
False. To compensate for metabolic alkalosis, breathing slows so that carbon dioxide is retained and more carbonic acid forms. This compensation is limited because the body can tolerate only so much carbon dioxide retention.
Category: Acid-Base Disorders