Small uncharged molecules such as oxygen and carbon dioxide cross the lipid bilayer by simple diffusion, moving from higher to lower concentration.
Missing Word
diffusion
Diffusion is the passive movement of a substance down its concentration gradient. Simple diffusion needs no carrier protein or energy, which suits small nonpolar molecules.
Category: Fluid Balance
Question 2
Fluid volume excess often causes visible swelling of the ankles, legs and feet, called edema.
Missing Word
edema
Edema is the buildup of excess fluid in the interstitial space. It is a key sign of fluid overload from heart failure, kidney disease or drugs that retain sodium and water.
Category: Fluid Balance
Question 3
An IV solution whose osmolality matches that of plasma, causing no net movement of water into or out of cells, is called isotonic.
Missing Word
isotonic
Isotonic solutions such as 0.9% sodium chloride and lactated Ringer's solution expand extracellular volume without shifting water into or out of cells, so they are used to treat dehydration.
Category: IV Solutions
Question 4
Albumin, dextran and hydroxyethyl starch are colloids, large-molecule solutions that remain in the vascular space and expand blood volume.
Missing Word
colloids
Colloids contain molecules too large to cross capillary walls, so they raise oncotic pressure and pull fluid from the tissues into the bloodstream.
Category: IV Solutions
Question 5
The adrenal mineralocorticoid aldosterone causes the kidneys to retain sodium and excrete potassium.
Missing Word
aldosterone
Aldosterone, made by the adrenal cortex, acts on the distal nephron to reabsorb sodium and water while secreting potassium, which links sodium retention to potassium loss.
Category: Electrolyte Regulation
Question 6
Parathyroid hormone raises serum calcium, while calcitonin, made by the parafollicular cells of the thyroid gland, lowers it.
Missing Word
calcitonin
Calcitonin inhibits osteoclasts, which reduces calcium release from bone, so it opposes parathyroid hormone. It can be given to treat hypercalcemia.
Category: Electrolyte Regulation
Question 7
A serum sodium level below the normal range, often from excess water intake, heart failure or kidney disease, is called hyponatremia.
Missing Word
hyponatremia
Hyponatremia is a low serum sodium concentration. Because water moves into cells, severe cases cause headache, confusion, seizures and coma.
Category: Electrolyte Regulation
Question 8
A transfusion reaction in which the recipient's antibodies break apart the donor's red blood cells is called a hemolytic reaction.
Missing Word
hemolytic
A hemolytic reaction occurs when antibodies attack incompatible donor red cells, often from an ABO mismatch. It can cause fever, back pain, hypotension and kidney injury, and the transfusion must be stopped at once.
Category: Blood Products
Question 9
Severe vitamin C deficiency causes scurvy, a disease marked by bleeding gums and poor wound healing.
Missing Word
scurvy
Scurvy results from a lack of ascorbic acid, which is needed to make collagen. Without collagen, blood vessels and healing tissue become weak.
Category: Vitamins
Question 10
In children, severe vitamin D deficiency causes soft, deformed bones in a disease called rickets.
Missing Word
rickets
Rickets is the childhood disease of poorly mineralized bone caused by vitamin D deficiency. In adults the same deficiency causes osteomalacia.
Category: Vitamins
Question 11
Vitamin B12 must bind intrinsic factor from the stomach before it can be absorbed in the ileum, the final section of the small intestine.
Missing Word
ileum
The ileum is the last part of the small intestine, where vitamin B12 bound to intrinsic factor is taken up. Loss of intrinsic factor, as in pernicious anemia, or removal of the ileum prevents this absorption, so vitamin B12 is then replaced by injection or another route that does not depend on intrinsic factor.
Category: Vitamins
Question 12
Wilson disease is an inherited disorder in which the mineral copper builds up in the liver and brain.
Missing Word
copper
Copper is needed for red blood cell formation and collagen production, but in Wilson disease it accumulates to toxic levels and is removed with chelators such as penicillamine and trientine.
Category: Minerals
Question 13
The mineral zinc supports immunity and wound healing, and its deficiency can cause loss of taste.
Missing Word
zinc
Zinc is needed for immune function, protein and DNA synthesis, wound healing and taste. Deficiency can occur with Crohn disease, celiac disease and pregnancy.
Category: Minerals
Question 14
The inherited disorder in which the body absorbs and stores too much iron is called hemochromatosis.
Missing Word
hemochromatosis
Hemochromatosis causes iron to build up in organs such as the liver, heart and pancreas. Treatment removes iron by phlebotomy or with iron chelating drugs.
Category: Minerals
Question 15
Drugs such as deferoxamine and succimer bind heavy metals into stable complexes that are excreted, a process called chelation.
Missing Word
chelation
Chelation is the binding of a metal ion by a drug into a complex that the body can excrete in urine or feces. It is used for iron overload, copper overload and lead poisoning.
Category: Minerals