Homeostasis is the body's ability to keep a stable internal environment despite changes inside and outside the body.
Missing Word
Homeostasis
Homeostasis keeps variables such as temperature, fluid balance, pH, and blood glucose within a narrow range. It depends on organ systems working together through feedback loops.
Category: Homeostasis Basics
Question 2
During childbirth, oxytocin is the hormone that strengthens uterine contractions in a positive feedback loop.
Missing Word
oxytocin
Oxytocin is released from the posterior pituitary gland. Stronger contractions push the baby against the cervix, which triggers more oxytocin release until delivery ends the cycle.
Category: Feedback Loops
Question 3
The pump that moves Na+ out of cells and K+ into them uses energy released from ATP.
Missing Word
ATP
ATP, adenosine triphosphate, is the cell's energy molecule. Active transport pumps break it down to power the movement of ions against their concentration gradients.
Category: Osmotic Equilibrium
Question 4
Interstitial fluid is the extracellular fluid that surrounds tissue cells outside the blood vessels.
Missing Word
Interstitial
Interstitial fluid lies between cells and is part of the extracellular compartment, along with intravascular and transcellular fluid. Fluid shifts between it and the capillaries are governed by hydrostatic and oncotic pressure.
Category: Fluid Compartments
Question 5
A cation is an ion that has fewer electrons than protons, giving it a positive charge.
Missing Word
cation
Cations form when atoms lose electrons. Calcium, magnesium, potassium, and sodium are the major cations in body fluids.
Category: Ions and Electrolytes
Question 6
Tonicity is a solution's ability to make a cell gain or lose water, measured relative to the cell's cytoplasm.
Missing Word
Tonicity
Tonicity describes the effect of a solution on cell volume. It is related to osmolality but not identical, because it depends on solutes that cannot freely cross the cell membrane.
Category: Osmolality and Tonicity
Question 7
An anion is an ion that has gained one or more electrons, so it carries an overall negative charge.
Missing Word
anion
An anion has more electrons than protons, which gives it a negative charge. Chloride, bicarbonate, and phosphate are important anions in body fluids, balancing the positive charge of cations.
Category: Ions and Electrolytes
Question 8
Solutes are substances that are dissolved in a solvent such as water.
Missing Word
Solutes
In body fluids the solutes include electrolytes, glucose, urea, and proteins. Their concentration determines osmolality and drives water movement by osmosis.
Category: Osmolality and Tonicity
Question 9
Hyponatremia is an abnormally low blood level of the electrolyte that is most abundant outside cells, and older adults are at increased risk for it.
Missing Word
Hyponatremia
Hyponatremia means low sodium in the blood. Age-related changes in the kidneys make older adults more vulnerable to it.
Category: Special Populations
Question 10
Calcium is the positively charged electrolyte that is stored mainly in bone and is required for blood clotting.
Missing Word
Calcium
Calcium is a major cation in body fluids. Most of the body's supply is held in bones and teeth, and the ion in blood is needed for clotting, muscle contraction, and nerve signaling.
Category: Ions and Electrolytes
Question 11
Bicarbonate is the negatively charged ion that acts as the main pH buffer in extracellular fluid.
Missing Word
Bicarbonate
Bicarbonate, written HCO3-, combines with excess hydrogen ions to limit changes in pH. This buffering helps keep blood pH within its narrow normal range.
Category: Ions and Electrolytes
Question 12
Urea, a nitrogen waste product made by the liver, is one of the dissolved particles measured to estimate blood osmolality.
Missing Word
Urea
Urea forms when the liver breaks down amino acids and is excreted by the kidneys. It is included with sodium and glucose in the calculated serum osmolality, and it raises osmolality noticeably when kidney function fails.
Category: Osmolality and Tonicity
Question 13
Shivering is an involuntary contraction of skeletal muscles that generates heat when body temperature falls.
Missing Word
Shivering
Shivering is an effector response in the temperature negative feedback loop. The rapid muscle contractions produce heat while skin blood vessels constrict to keep that heat in.
Category: Temperature Regulation
Question 14
Hyperkalemia is an abnormally high level of potassium in the blood, a risk when aging kidneys excrete potassium less effectively.
Missing Word
Hyperkalemia
Hyperkalemia means high blood potassium. Because the kidneys remove most excess potassium, declining kidney function in older adults raises the risk.
Category: Special Populations
Question 15
Sodium is the most abundant positively charged ion in extracellular fluid.
Missing Word
Sodium
Sodium is the main cation outside cells and the largest contributor to the osmolality of extracellular fluid. Where it goes, water tends to follow, so it strongly influences fluid balance.
Category: Ions and Electrolytes