Chapter 25 - Fluid, Electrolyte, and Acid-Base Homeostasis

Substances that function to resist large swings in pH are called __________.

buffers *Buffers utilize weak acids and weak bases to minimize pH changes in the ECF and the ICF.

Which of the following accounts for about 60% of our total body water?

cytosol

What is the most common cause for hypernatremia?

dehydration

Which of the following is an excess accumulation of interstitial fluid?

edema

This electrolyte imbalance can be caused by renal failure, aldosterone insufficiency, cellular destruction from severe burns or trauma, and accidental administration or ingestion of excess potassium salts.

hyperkalemia

The most common cause of this electrolyte imbalance is dehydration.

hypernatremia

Which of the following is an effect of dehydration or total body water decrease?

hypernatremia *Loss of total body water will result in increased extracellular electrolyte concentrations, particularly that of sodium ions, causing hypernatremia. Return to Assignment

This electrolyte imbalance is normally caused by diuretics.

hypokalemia

This electrolyte imbalance is caused by an abnormal decrease in the plasma sodium ion concentration.

hyponatremia

What condition accompanies overhydration, or hypotonic hydration?

hyponatremia

What leads to respiratory acidosis?

hypoventilation

Which ions are critical for the activation of some enzymes?

magnesium ions

Which hormone has NO role in potassium ion regulation?

parathyroid hormone (PTH)

A patient is given excessive IV fluids and is experiencing overhydration. Which of the following would you expect?

plasma hydrostatic pressure will increase *Overhydration will result in an increase in blood pressure and in plasma hydrostatic pressure. This will result in a larger hydrostatic pressure gradient driving water out of plasma into interstitial fluid.

What is most abundant intracellular cation?

potassium ion

How much water does the average person lose per day?

2.5 liters

Select the blood pH that represents acidosis.

7.24

The normal range of blood pH is __________.

7.35 to 7.45 *The body must maintain the pH within this narrow, slightly alkaline range, because even a slight deviation can have disastrous consequences for our cells.

Determine the effect of hypocalcemia on the heart.

As a result of hypocalcemia, the plateau phase of the cardiac muscle cell action potential is lengthened.

Why are chlorine ions important?

Chlorine ions are involved in the production of stomach acids.

What effect does an increase in antidiuretic hormone (ADH) have on the volume of extracellular fluid (ECF)?

ECF increases when antidiuretic hormone (ADH) is present.

What best describes hydrostatic pressure?

Hydrostatic pressure is the force that fluids exert against the capillary wall.

Mrs. Frykholm is experiencing diabetic ketoacidosis, which causes metabolic acidosis. She has experienced damage to her kidneys from diabetes mellitus. Predict how her body compensates to return her blood pH to normal.

Hyperventilation.

Which of the following ions is a component of hydroxyapatite crystals in bone matrix?

PO43− *Calcium ions and phosphate ions (PO43−) are found together in hydroxyapatite crystals.

Which of the following is NOT a compensation for respiratory acidosis?

The kidney tubule cells will increase reabsorption of calcium ions from the filtrate.

Which of the following represents appropriate compensation for metabolic acidosis?

The retention of bicarbonate ions in the kidneys *The bicarbonate ions will then be used by the carbonic acid bicarbonate buffer system to neutralize the extra acid.

Metabolic water (or water of oxidation) amounts to a total gain of about 250 ml of water per day.

True

The hormone PTH causes __________.

a decrease in the reabsorption of phosphate ions *When phosphate ions are present in large numbers, they bind calcium ions and so reduce the number of free calcium ions. Therefore, the body must excrete more phosphate ions and retain more calcium ions; PTH is responsible for this regulation.

Which hormone influences the concentration of hydrogen ions in the filtrate formed by the kidneys?

aldosterone

Identify the hormones responsible for increasing sodium ion retention.

angiotensin-II and aldosterone

A patient present with severe metabolic alkalosis. The appropriate respiratory compensation would be __________.

decreased respiratory rate *Decreasing the respiratory rate increases Pco2 and therefore decreases pH

A child is brought to the ER after prolonged vomiting and diarrhea. Which of the following is one of the symptoms this child will present with?

decreased urine production *This child is dehydrated; therefore, ADH and the RAAS system will stimulate water reabsorption in the kidneys and reduce urine production, a condition known as oliguria.

Which of the following is not an electrolyte?

glucose *Electrolytes are substances that break down, or dissociate, into ions when placed in water. Since glucose is covalently bound, it would not dissociate into ions when in water.

The pH of the blood primarily depends upon a normal concentration of:

hydrogen ions.

This electrolyte imbalance is normally caused by hyperparathyroidism.

hypercalcemia

Which condition is usually due to hyperparathyroidism?

hypercalcemia

Water loss from the body that we do not notice is known as:

insensible water loss.

What leads to metabolic alkalosis?

prolonged vomiting and the loss of acidic stomach contents

To compensate for this acid-base imbalance, the kidneys secrete more bicarbonate ions and reabsorb more hydrogen ions.

respiratory alkalosis

Hyperventilation causes __________, and hypoventilation causes __________.

respiratory alkalosis; respiratory acidosis *Hyperventilation can be caused by anxiety, whereas hypoventilation can be caused by COPD.

What is the most abundant extracellular cation?

sodium ion

Which system is responsible for the most common route of water loss from the body?

urinary system

Under what conditions might it be beneficial to administer a hypertonic saline solution to a patient?

If the patient is overhydrated, then a hypertonic solution could be used to draw the water out of their cells. *Overhydration, also known as hypotonic hydration, results when the volume of the ECF increases and its osmotic pressure falls. Cells exposed to the hypotonic ECF swell as water enters the cells by osmosis. If a patient is overhydrated, then a hypertonic saline could be used to draw the excess water out of the cells.