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Problem L2.2
A woman begins a diet and exercise regimen and loses 30 lb. Will her total body water increase, decrease, or stay the same? Why?
Problem L2.3
Explain how the amount of water in the body affects the concentration of ions and solutes in the ECF.
Problem L2.4
Diabetic ketoacidosis is characterized by an increased level of ketone bodies, which causes metabolic acidosis. A patient in diabetic ketoacidosis will have an altered rate of ventilation. Will the patient be hyperventilating or hypoventilating? How will a change in the rate and depth of ventilation compensate for an acidosis that is metabolic in nature?
Problem L3.1
Elise Anderson is a 6-year-old girl who presents to the emergency department with a history of vomiting for the past 3 days. The nurse notices that her respiratory rate is abnormally low. What is the likely reason for this change in ventilation? Predict what Elise's arterial blood gas values would show.
Problem L3.2
What do you think has happened to Elise's ECF volume and osmolarity over the past 3 days? Will this lead to a change in the volume of water in the cytosol of her cells? Explain.
Problem L3.3
Ms. Johanssen is a patient in the hospital. The nurse examines her laboratory reports and notices that she has developed hyperkalemia and acidosis over the past several days. On closer examination of her medical chart, the nurse also sees that her physician recently doubled her dose of spironolactone, an aldosterone-blocking diuretic. How does this explain her laboratory findings?
Problem L3.4
A laboratory printout of arterial blood gases indicates that a patient has an increased Pco₂ , decreased pH, and normal bicarbonate ion concentration. Is this patient in acidosis or alkalosis? Is the pH disturbance respiratory or metabolic in nature? Explain your reasoning. How long do you think the patient has had this pH disturbance? (Hint: Look at the bicarbonate ion concentration. What system controls the concentration of bicarbonate ions, and how quickly does it compensate for pH disturbances?)
Problem L3.5
What happens to the concentration of sodium ions in the ECF if you consume a large amount of salt without consuming any water? How will this affect the osmotic pressure of the ECF? Why could this lead to an elevation in blood pressure?
Problem L2.1
Your friend argues that all water conducts electricity, regardless of what it contains. You prepare three liquids to test this hypothesis: one with distilled water (with no solutes, only water molecules), one with 5% glucose in distilled water, and one with 5% sodium chloride in water. Which of these solutions, if any, will conduct an electric current? Explain.
Problem 1
List the effects of each of the following hormones on electrolyte balance. Note that some hormones affect more than one electrolyte.
a. Angiotensin-II
b. Aldosterone
c. Parathyroid hormone
d. Vitamin D
e. Atrial natriuretic peptide
Problem 2
How does an electrolyte differ from a nonelectrolyte?
Problem 3
What happens to the pH of a solution when hydrogen ions are added?
a. The pH increases.
b. The pH decreases.
c. The pH does not change.
d. The pH does not measure hydrogen ion concentration.
Problem 4
As a percentage of body weight, the total body water tends to be higher in ________ and lower in ________ .
a. infants; men
b. women; men
c. men; infants
d. infants; women
Problem 5
A cell in a/an ________ fluid will lose water, and a cell in a/an ________ fluid will gain water.
Problem 6a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
a. The thirst mechanism is mediated by osmoreceptors located in the cerebral cortex.
Problem 6b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
b. The sensible water loss includes the water lost from the body via the skin and the respiratory system.
Problem 6c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
c. The main hormone that regulates fluid balance is antidiuretic hormone (ADH).
Problem 6d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
d. Atrial natriuretic peptide promotes water retention in the kidneys and increases the amount of water in the body.
Problem 6e
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
e. Dehydration is characterized by a decreased volume and increased osmolarity of the ECF.
Problem 7
Which of the following is false with respect to sodium ions in human physiology?
a. Sodium ions are the most abundant extracellular cation.
b. Sodium ions are an important osmotic particle in the ECF.
c. The entry of sodium ions into a cell causes depolarization.
d. Sodium ions are more concentrated in the cytosol than in the ECF.
Problem 8
Which of the following statements best describes the principle of mass balance?
a. The amount of a variable that is gained by the body through ingestion equals the amount that is lost from the body.
b. The body maintains a stable mass at all times.
c. The amount of each variable brought into the body must be balanced by all other variables.
d. The amount of a variable ingested is regulated by a positive feedback loop.
Problem 9
Which of the following effects tend to be caused by hypernatremia?
a. Inhibition of ADH secretion
b. Cellular crenation
c. Cellular swelling
d. Increased urine production
Problem 10a
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
a. Potassium ions are responsible for the repolarization phase of the action potential.
Problem 10b
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
b. Insulin, aldosterone, and epinephrine stimulate the uptake of potassium ions into cells.
Problem 10c
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
c. Hyperkalemia tends to decrease the resting membrane potential and hyperpolarize excitable cells.
Problem 10d
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
d. Hypocalcemia causes neurons to become hyperexcitable, leading to potential tetanic contractions.
Problem 10e
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
e. Chloride ions are generally reabsorbed from the kidneys, along with bicarbonate ions.
Problem 11
The biggest source of metabolic acids in the body is:
a. Lactic acid
b. Ketone bodies
c. Carbon dioxide
d. Uric acid
Problem 12
What is the main buffer system of the ECF?
a. Protein buffer system
b. Carbonic acid–bicarbonate ion buffer system
c. Phosphate buffer system
d. None of the above
Problem 13
Explain what happens to the pH of a buffered solution when hydrogen ions are added. Why does this happen?