Question 1

Periodontal disease can be exacerbated by a deficiency of calcium.Oral signs of osteoporosis may include increased density of the lamina dura.

Accepted Answer

The first statement is true; the second is false.It is true that the breakdown of periodontal tissue is exacerbated by osteoporosis.Oral signs of osteoporosis can include loss of calcium in the alveolar bone.The lamina dura,the radiolucent area adjacent to the periodontal ligament,does not increase in density.Any effects related to osteoporosis would be degenerative.

Question 2

Milk and other dairy products are preferred sources of calcium because lactose enhances calcium absorption.

Accepted Answer

Both the statement and the reason are correct and related.Milk and other dairy products supply most of the available calcium,so they are the preferred sources of calcium.Not only are dairy products naturally high in calcium content,but also their inherent lactose and other nutrient content enhance calcium absorption.Milk also provides other essential nutrients.

Question 3

High levels of calcium within the urine is called:

Accepted Answer

An increased level of calcium within the urine is called hypercalciuria.Hypercalcemia is high levels of calcium within the blood.Hyperplasia is an increase in cell size,whereas hypoplasia is a decrease in cell size.

Question 4

Magnesium plays a major role in blood pressure regulation.The strongest benefit occurs when magnesium is obtained from supplements.

Accepted Answer

The first statement is true; the second is false.Magnesium is vital to the structural integrity of heart muscle and plays a major role in blood pressure regulation.It is also vital to other muscles and nerves.The strongest benefit of magnesium is derived from foods rather than supplements.

Question 5

Calcium supplements combined with vitamin D result in small but significant reductions in bone loss.Benefits of this combination are significant because the bioavailability of both vitamin D and calcium is enhanced in combined supplements.

Accepted Answer

The first statement is true; the second is false.The benefits of combined vitamin D and calcium supplementation are less than expected because of the limited bioavailability of supplemental calcium.Bioavailability refers to the amount of a nutrient available physiologically based on its absorption rate.

Question 6

Consumption of soft drinks is often recommended to increase serum phosphorus levels.Hyperphosphatemia can be a risk factor cardiac disease.

Accepted Answer

The first statement is false; the second is true.Consumption of more than two to three cans of soft drink daily in place of milk can interrupt the calcium-to-phosphorus balance.Adequate intake of phosphorus from dairy products is thought to control blood pressure.Note that phosphorus is widespread in foods,and a deficiency is unlikely.Soft drinks are never recommended to increase phosphorus levels.

Question 7

Each is true of calcium supplements,except one.Which is the exception?

Accepted Answer

Calcium citrate is 21% calcium by weight.Other forms of calcium in supplements or fortified foods include calcium gluconate,calcium sulfate,and calcium lactate.

Question 8

Each is true of osteoporosis,except one.Which is the exception?

Accepted Answer

Osteoporosis is caused by numerous factors including decreased estrogen,inadequate calcium or vitamin D intake,and lack of weight-bearing exercise.It is an age-related disorder that is characterized by decreased bone mass.

Question 9

Individuals should consume 30% of the daily value or 300 mg of calcium per serving three or four times daily because under normal conditions,less than one third of the calcium consumed is absorbed.

Accepted Answer

Both the statement and the reason are correct and related.Calcium is best absorbed by the body when consumed in smaller amounts and ingested several time throughout the day.

Question 10

Rickets cannot occur when calcium levels are sufficient because formation of rickets is solely dependent upon blood (serum)calcium level.

Accepted Answer

Neither the statement nor the reason is correct.Rickets results in porous,soft,and sometimes twisted bones.It is the result of an inadequate amount of calcium deposits in the bone during childhood.Interestingly,rickets can occur during times of adequate calcium intake if vitamin D is insufficient,because absorption and utilization of calcium is dependent on adequate vitamin D levels.

Question 11

Magnesium is the third most prevalent mineral in teeth.Enamel contains about three times more magnesium than dentin.

Accepted Answer

The first statement is true; the second is false.Dentin contains about two times the amount of magnesium as does enamel.

Question 12

Which percentage most approximates the dietary phosphorus absorbed in the jejunum?

Accepted Answer

Approximately 60% to 70% of dietary phosphorus is absorbed in the jejunum.Its absorption can be inhibited by the same dietary factors affecting calcium absorption-phytate,excessive amounts of fats,iron,aluminum,and calcium.Note that the jejunum is the middle part of the small intestine.

Question 13

Each is true of the calcium-to-phosphorus ratio,except one.Which is the exception?

Accepted Answer

Decreased bone density caused by insufficient calcium is a slow process.Despite wide variation in calcium intake,serum calcium is relatively constant because each cell has a vital need for calcium.

Question 14

Hypocalcemia,or deficient levels of calcium in the blood,can be caused by overdoses of cholecalciferol or excessive amounts of vitamin D preparations.Hypocalcemia results in tetany,a neuromuscular disorder.

Accepted Answer

The first statement is false; the second is true.Hypocalcemia is not caused by cholecalciferol.Depressed serum calcium levels (hypocalcemia)may be caused by hypoparathyroidism,some bone diseases,certain kidney diseases,and low serum protein levels.It is true that hypoglycemia results in tetany,a neuromuscular disorder of uncontrollable cramps and tremors involving the muscles of the face,hands,feet,and eventually the heart.Note that overdoses of cholecalciferol,vitamin D₃,can cause hypercalcemia.

Question 15

Calcium balance,an intake that equals excretion,depends solely on adequate calcium intake.Although hormones such as PTH are involved in phosphorus balance,hormonal influence on calcium balance is insignificant.

Accepted Answer

Both statements are false.Calcium balance does not depend solely on adequate calcium intake.Several hormones,including parathyroid hormone (PTH),estrogen,glucocorticoids,and thyroid hormone help to regulate calcium absorption.

Question 16

Magnesium supplements are frequently recommended by dietitians because it is difficult to get enough magnesium from food alone.

Accepted Answer

Neither the statement nor the reason is correct.Excessive amounts of magnesium can be obtained from supplements.For this reason,supplements are reserved for patients with specific diseases or under stressful conditions.Note that decreased food intake,impaired magnesium absorption,and the use of certain diuretics may be situations in which magnesium supplements are advised.

Question 17

Each is true of phosphorus,except one.Which is the exception?

Accepted Answer

Phosphorus,the second most abundant mineral in the body,is present in all body cells and is necessary for almost every aspect of metabolism.It is vital to transfer and release of energy stores as adenosine triphosphate (ATP,composition of phospholipids,DNA,and RNA).

Question 18

Patients with achlorhydria (absence of hydrochloric acid in the stomach)should not take calcium with meals.Mineral oils and some laxatives can decrease calcium absorption.

Accepted Answer

Both statements are false.Patients with achlorhydria (absence of hydrochloric acid in the stomach)might not absorb calcium supplements on an empty stomach and should take them with meals.Although mineral oil and some laxatives can decrease calcium absorption,forms of sugar such as lactose,dextrose,and sucrose enhance calcium absorption.

Question 19

Hypercalcemia,high levels of calcium in the blood,is almost always caused by excess dietary calcium intake.This can result in renal proliferation and increased kidney function.

Accepted Answer

Both statements are false.Hypercalcemia is increased level of calcium in the blood.Rarely the result of dietary intake,hypercalcemia can result in renal insufficiency,kidney stones or hypercalciuria (high levels of calcium in the urine).

Question 20

Magnesium toxicity has been associated with kidney failure because the kidneys regulate plasma magnesium levels.

Accepted Answer

Both the statement and the reason are correct and related.Because kidneys regulate plasma magnesium levels,toxicity has been associated with kidney failure.Pertinent to kidney function,magnesium is involved in more than 300 enzymatic reactions,including energy metabolism,insulin activity,and glucose use.All these functions rely on proper kidney function for processing and excretion of by-products.

Quiz 9: Minerals Essential for Calcified Structures