ch 26 questions Flashcards
What is the major cation in the extracellular fluid (ECF)?
NA
Which fluid compartment of the body contains the greatest volume of water?
intracellular fluid
Select the route of water output that is considered to be insensible water loss.
expired air
Choose the correct statement regarding disturbances in water balance.
In dehydration, excessive water is lost from ECF, ECF osmotic pressure falls, and cells shrink.
In dehydration, the loss of water from the ECF causes solutes to become more concentrated, thereby increasing the ECF osmotic pressure. This greater ECF osmotic pressure pulls water out of cells, causing them to shrink.
In hypotonic hydration, the ECF osmotic pressure falls, cells lose water to ECF by osmosis, and cells shrink.
In hypotonic hydration, the falling ECF osmotic pressure causes cells to swell when water moves into them by osmosis.
In dehydration, the ECF osmotic pressure rises, water moves into cells by osmosis, and cells swell.
In dehydration, the rising ECF osmotic pressure causes cells to shrink as water moves by osmosis out of the cells towards the more concentrated ECF environment.
In hypotonic hydration, excessive water enters the ECF, water enters cells by osmosis, and cells swell.
In hypotonic hydration, excessive water enters the ECF, water enters cells by osmosis, and cells swell.
Which pH value for arterial blood indicates acidosis?
7.3
Select the true statement regarding chemical buffer systems.
The protein buffer system is the most important buffer inside cells.
Which of the following describes how the kidneys normally handle hydrogen and bicarbonate ions?
The kidneys secrete bicarbonate ions and reabsorb hydrogen ions.
The kidneys secrete hydrogen ions and reabsorb bicarbonate ions.
The kidneys secrete both hydrogen and bicarbonate ions.
The kidneys reabsorb both hydrogen and bicarbonate ions.
The kidneys secrete hydrogen ions and reabsorb bicarbonate ions.
What is the most important urinary buffer of H+?
phosphate buffer system
What removes nonvolatile (fixed) acids from the body?
kidneys
How does the body compensate for respiratory acidosis?
kidneys retain more bicarbonate in blood
What could cause metabolic alkalosis?
Vomiting
Describe the thirst mechanism, indicating how it is triggered and terminated.
The thirst mechanism is primarily triggered by an increase in blood osmolality or a decrease in blood volume, both of which are detected by osmoreceptors in the hypothalamus. When osmolality rises, it causes the sensation of thirst, prompting water intake. The mechanism is terminated when the osmolality returns to normal or when stretch receptors in the stomach signal the hypothalamus that fluid intake has occurred.
Explain why and how ECF osmolality is maintained.
ECF osmolality is maintained to ensure proper cell function, as water movement depends on osmotic gradients. The body regulates ECF osmolality through antidiuretic hormone (ADH), which increases water reabsorption in the kidneys when osmolality is high, and decreases reabsorption when osmolality is low.
Explain why and how total body sodium content, ECF volume, and blood pressure are jointly regulated.
Sodium levels directly affect ECF volume because water follows sodium to maintain osmotic balance. Higher sodium levels increase ECF volume, which, in turn, raises blood pressure. The body regulates this through mechanisms like aldosterone (which promotes sodium reabsorption) and the renin-angiotensin-aldosterone system (RAAS), which controls blood pressure and sodium balance.
Describe the role of the respiratory system in controlling acid-base balance.
The respiratory system controls acid-base balance by regulating the levels of carbon dioxide (CO₂) in the blood. When CO₂ levels rise, it combines with water to form carbonic acid, lowering pH. The respiratory system responds by increasing breathing rate to expel CO₂, thereby reducing acidity. Conversely, a lower CO₂ level reduces acidity, and the breathing rate decreases.
Explain how the chemical buffer systems resist changes in pH.
Chemical buffers, such as bicarbonate, phosphate, and protein buffers, resist pH changes by binding or releasing hydrogen ions (H⁺). If pH drops, buffers bind excess H⁺, and if pH rises, buffers release H⁺ to stabilize the pH.
Plasma carbon dioxide levels:
High CO₂ levels lead to the formation of carbonic acid, which dissociates to release H⁺, prompting the kidneys to excrete H⁺ to maintain pH.
Phosphate
Phosphate acts as a buffer in the kidneys, helping to neutralize H⁺ and allowing its excretion.
Sodium bicarbonate reabsorption:
The kidneys reabsorb sodium bicarbonate to neutralize excess H⁺, thus helping to maintain acid-base balance.
Body water content is greatest in:
infants
Potassium, magnesium, and phosphate ions are the predominant electrolytes in:
intracellular fluid
Sodium balance is regulated primarily by control of amount(s):
excreted in urine
Two main substances regulated by the influence of aldosterone on the kidney tubules.
Sodium (Na⁺) and potassium (K⁺).
Two substances regulated by parathyroid hormone.
Calcium (Ca²⁺) and phosphate (PO₄³⁻).
Two substances secreted into the proximal convoluted tubules in exchange for sodium ions.
Hydrogen ions (H⁺) and potassium ions (K⁺).
Part of an important chemical buffer system in plasma.
Bicarbonate (HCO₃⁻) buffer system.
Two ions produced during catabolism of glutamine.
Ammonium (NH₄⁺) and bicarbonate (HCO₃⁻).
Substance regulated by ADH’s effects on the renal tubules.
Water
Which of the following factors will enhance ADH release?
increase in ECF osmolality
In an individual with metabolic acidosis, a clue that the respiratory system is compensating is provided by:
rapid, deep breathing
Intracellular fluid (ICF)
Located inside cells, approximately 25 liters in an average adult.
