180 Questions
Which of the following factors can impair calcium absorption?
Increased stomach acid
What is the recommended dietary allowance (RDA) of calcium for females aged 19 to 50 years?
1000 mg/day
Which of the following food sources has the highest bioavailability of calcium?
Dairy products
What is the effect of sodium intake on urinary calcium excretion?
It increases urinary calcium excretion
What is the effect of protein intake on renal calcium excretion?
It increases renal calcium excretion
What is the effect of calcium intake on non-heme iron absorption?
It decreases non-heme iron absorption
Which type of bone is primarily non-living material?
Cortical bone
What is the main function of osteoclasts?
To resorb (dissolve) bone
What is the bioavailability of a nutrient?
The rate at which a nutrient is absorbed
What is the main component of the bone matrix?
Collagen
What is the primary source of calcium in the body?
The skeleton (bones)
What are provitamins?
Inactive forms of some vitamins found in foods
Which hormone stimulates bone resorption (dissolving of bone)?
Parathyroid hormone (PTH)
At what age does peak bone mass development occur?
Between 12 and 30
What is the purpose of bone modeling (remodeling)?
To replace damaged bones
What is the most common intracellular messenger involved in various functions such as muscle contraction and glucose breakdown?
Calcium
What is the main role of calcium in the body?
All of the above
What is the primary location of calcium absorption in the digestive system?
Small intestine
Which of the following is NOT a risk factor for osteoporosis?
High body weight
What is the range of age when peak bone mass (PBM) is achieved?
20-30 years
What is the most efficient absorption rate for calcium supplements?
35%
Where is the majority of phosphorus (P) found in the body?
Bone
Which of the following is NOT a food source of phosphorus?
Spinach
What is the Recommended Dietary Allowance (RDA) for phosphorus for individuals aged 9-18 years?
1250 mg/day
Which of the following is a symptom of hypophosphatemia?
Muscle weakness
What is the Tolerable Upper Intake Level (UL) for phosphorus for people aged 9-70 years?
4 g/day
What is the function of magnesium in the body?
Supports immune function
What are the food sources of magnesium?
All of the above
What is the recommended dietary allowance (RDA) of magnesium for males aged 19-30 years?
400 mg/day
What is the primary function of fluoride in the body?
Protects against demineralization of bone & teeth
Which type of bone is primarily non-living material?
Cortical bone
What is the main component of the bone matrix?
Collagen
What is the primary function of osteoclasts?
Resorb (dissolve) bone
What are provitamins?
Inactive forms of some vitamins found in foods
What is the main role of calcium in the body?
Muscle contraction
What is the bioavailability of a nutrient?
The extent to which a nutrient is absorbed
Which of the following factors can impair calcium absorption?
Decreased stomach acid
What is the Tolerable Upper Intake Level (UL) for calcium for individuals aged 9-18 years?
2500 mg/day
What is the effect of protein intake on renal calcium excretion?
Protein intake increases renal calcium excretion
What is the primary location of calcium absorption in the digestive system?
Small intestine
What is the bioavailability of calcium supplements?
30%
What is the recommended dietary allowance (RDA) of calcium for females aged 51+ years?
1200 mg/day
Which of the following is a symptom of hyperphosphatemia?
Bone pain
What is the Tolerable Upper Intake Level (UL) for magnesium for people aged 9-70 years?
4 g/day
What is the primary function of phosphorus in the body?
Bone mineralization
What is the bioavailability of magnesium from food sources?
About 50%
What is the Recommended Dietary Allowance (RDA) of phosphorus for males aged 9-13 years?
240 mg/day
What is the most abundant divalent cation in cells?
Magnesium
What is the primary function of calcitonin in the body?
Inhibits bone resorption
What is the main role of PTH (parathyroid hormone) in the body?
Stimulates bone resorption (dissolving of bone)
What is the primary source of vitamin D in the body?
Sunlight exposure
What is the main function of growth factors in bone cell action?
Promote bone development and repair
What is the primary role of glucocorticoids in bone cell action?
Stimulate bone resorption (dissolving of bone)
What is the primary function of osteocytes in bone cell action?
Maintain bone integrity and function
Which of the following is a risk factor for osteoporosis?
Postmenopausal (no protection from estrogen)
What is the primary function of fluoride in the body?
A component of hydroxy- and fluorapatite; phospholipids in cell membranes; nucleic acids (RNA, DNA); and almost all enzymes
What is the effect of sodium intake on urinary calcium excretion?
Increases urinary calcium excretion
What is the primary location of calcium absorption in the digestive system?
Small intestine
What is the recommended dietary allowance (RDA) of magnesium for males aged 19-30 years?
450 mg/day
What is the most efficient absorption rate for calcium supplements?
40%
Which of the following factors can increase urinary calcium excretion?
Increased sodium intake
What is the bioavailability of calcium from supplements?
30%
Which of the following is the most potent inhibitor of calcium absorption?
Oxalic acid
What is the effect of protein intake on renal calcium excretion?
Increases renal calcium excretion
Which of the following is NOT a risk factor for osteoporosis?
High protein intake
What is the primary function of calcitonin in the body?
Decrease blood calcium levels
Which type of bone is primarily non-living material?
Cortical bone
What is the primary function of osteocytes in bone cell action?
To fill in pits left by osteoclasts
What is the main role of calcium in the body?
To maintain bone health
What is the primary source of vitamin D in the body?
Sunlight exposure
What is the effect of protein intake on renal calcium excretion?
Increases renal calcium excretion
What is the primary function of fluoride in the body?
To enhance bone growth
Which of the following is a risk factor for osteoporosis?
Postmenopausal (no protection from estrogen)
What is the primary function of osteoblasts in bone cell action?
Bone formation
What is the main function of vitamin D in the body?
Calcium absorption in the intestines
What is the primary role of PTH (parathyroid hormone) in the body?
Bone resorption
What is the primary source of vitamin D in the body?
Sun exposure
What is the recommended dietary allowance (RDA) of calcium for females aged 19 to 50 years?
1000 mg/day
Which of the following is the primary function of magnesium in the body?
Enzyme cofactors
What is the primary function of fluoride in the body?
Protects against demineralization of bone & teeth
What is the primary function of phosphorus in the body?
Bone mineralization
What is the primary role of vitamin D in the body?
Promotes calcium absorption in the small intestine
What is the Tolerable Upper Intake Level (UL) for phosphorus for people aged 9-70 years?
4 g/day
What is the bioavailability of magnesium from food sources?
50%
What is the primary function of osteocytes in bone cell action?
To replace damaged bones
What is the main role of calcium in the body?
To maintain blood calcium and phosphorus levels
What is the bioavailability of magnesium from food sources?
Low
What is the primary function of fluoride in the body?
To prevent tooth decay
What is the primary location of calcium absorption in the digestive system?
Small intestine
What is the most common intracellular messenger involved in various functions such as muscle contraction and glucose breakdown?
Calcium
Which hormone stimulates bone resorption (dissolving of bone)?
Parathyroid hormone (PTH)
During which phase of bone development does bone resorption exceed bone formation?
Age 30 to 40
What is the primary role of calcitonin in the body?
Prevents renal calcium reabsorption
What is the main function of osteoblasts?
Bone formation
What is the primary function of growth factors in bone cell action?
Promote bone formation
What is the primary location of calcium absorption in the digestive system?
Small intestine
Which type of bone is primarily non-living material?
Cortical bone
What is the primary function of osteoblasts in bone cell action?
To create a matrix and conditions for mineralization
What is the primary location of calcium absorption in the digestive system?
Small intestine
What is the primary role of PTH (parathyroid hormone) in the body?
To increase calcium reabsorption in the kidneys
What is the primary function of calcitonin in the body?
To decrease calcium resorption in bone
What are provitamins?
Inactive forms of some vitamins found in foods
Which of the following is a risk factor for osteoporosis?
Anorexia nervosa
What is the primary function of calcitonin in the body?
To decrease blood calcium levels
What is the primary function of osteoblasts in bone cell action?
To maintain bone mineralization
What is the primary role of glucocorticoids in bone cell action?
To stimulate bone resorption
What is the primary function of fluoride in the body?
To promote tooth mineralization
What is the primary function of phosphorus in the body?
To support growth and replace excretory losses
What is the recommended dietary allowance (RDA) of phosphorus for females aged 14-18 years?
410 mg/day
What is the primary function of magnesium in the body?
Enzyme cofactors
What is the bioavailability of magnesium from food sources?
About 50%
Which of the following is NOT a symptom of hypophosphatemia?
Osteomalacia
What is the primary role of fluoride in the body?
Protects against demineralization of bone & teeth
Which of the following is the most potent inhibitor of calcium absorption?
Phytate
Which of the following factors can impair calcium absorption?
Decreased stomach acid
What is the primary function of osteoclasts in bone cell action?
Bone resorption
What is the bioavailability of magnesium from food sources?
30%
What is the recommended dietary allowance (RDA) of phosphorus for individuals aged 9-18 years?
1100 mg/day
What is the primary source of vitamin D in the body?
Sunlight
What is the effect of protein intake on renal calcium excretion?
Increases renal calcium excretion
Which of the following factors can impair calcium absorption?
Decreased stomach acid
What is the bioavailability of calcium from dairy products?
30%
Which of the following is the most potent inhibitor of calcium absorption?
Oxalic acid
What is the recommended dietary allowance (RDA) of calcium for males aged 19 to 70 years?
1000 mg/day
What is the most efficient absorption rate for calcium supplements?
30%
Which of the following factors can increase urinary calcium excretion?
Protein intake
Which type of bone is primarily non-living material?
Cortical bone
What is the main function of vitamin D in the body?
Enhances calcium absorption
What is the primary function of osteoclasts?
Resorb (dissolve) bone
What is the primary function of growth factors in bone cell action?
Stimulate osteoblast activity
What is the primary role of PTH (parathyroid hormone) in the body?
Promotes bone resorption
What is the primary location of calcium absorption in the digestive system?
Small intestine
Which hormone stimulates bone resorption (dissolving of bone)?
Parathyroid hormone (PTH)
At what age does peak bone mass development occur?
Age 12 to 30
What is the primary function of calcitonin in the body?
Inhibits bone resorption
What is the main role of vitamin D in the body?
Increases blood calcium levels
What is the primary function of osteoclasts in bone cell action?
Stimulate bone resorption
What is the primary role of glucocorticoids in bone cell action?
Stimulate bone resorption
Which of the following is a risk factor for osteoporosis?
Chronic steroid use
What is the primary function of phosphorus in the body?
Plays a role in energy production
What is the relationship between low milk intake in childhood and hip fractures in post-menopausal women?
Increased risk of hip fractures
What is the most efficient absorption of calcium supplements?
With meals
What is the recommended daily intake of phosphorus for individuals aged 9-18 years?
1250mg/day
What is the primary location of phosphorus in the body?
Bone
Which of the following is a symptom of hypophosphatemia?
Rickets
What is the primary function of fluoride in the body?
Protects against demineralization of bone & teeth
What is the recommended dietary allowance (RDA) of magnesium for males aged 19-30 years?
420 mg/day
What is the primary function of magnesium in the body?
Enzyme cofactors
What is the Tolerable Upper Intake Level (UL) for phosphorus for people aged 9-70 years?
4 g/day
What is the bioavailability of calcium from supplements?
10-20%
Which hormone stimulates bone resorption (dissolving of bone)?
Parathyroid hormone (PTH)
What is the primary function of osteocytes in bone cell action?
Continual resorption and replacement of bone
What is the main function of osteoclasts?
Bone resorption
What is the primary role of glucocorticoids in bone cell action?
Bone resorption
What is the primary function of calcitonin in the body?
Bone formation
What is the primary role of fluoride in the body?
Mineralization of bone
Which of the following factors can impair calcium absorption?
Decreased stomach acid
Which of the following is NOT a source of calcium in the diet?
Spinach
What is the Recommended Dietary Allowance (RDA) of calcium for males aged 19 to 70 years?
1000 mg/day
Which of the following is a concern of hypercalcemia at high calcium intakes?
Milk alkali syndrome
Which of the following factors can increase urinary calcium excretion?
Protein intake
What is the bioavailability of calcium from dairy products?
30%
Which of the following is a risk factor for osteoporosis?
Postmenopausal (no protection from estrogen)
What is the primary function of growth factors in bone cell action?
Promote bone formation
What is the primary role of PTH (parathyroid hormone) in the body?
Stimulate bone resorption (dissolving of bone)
What is the main function of vitamin D in the body?
Regulate calcium absorption in the intestines
What is the primary function of calcitonin in the body?
Inhibit bone resorption (dissolving of bone)
What is the effect of protein intake on renal calcium excretion?
Increase renal calcium excretion
Which of the following is the primary function of magnesium in the body?
Enzyme cofactors
What is the primary function of fluoride in the body?
Protects against demineralization of bone & teeth
What is the recommended dietary allowance (RDA) of magnesium for males aged 19-30 years?
320 mg/day
What is the primary function of phosphorus in the body?
Bone mineralization
What is the recommended dietary allowance (RDA) of phosphorus for individuals aged 9-18 years?
360 mg/day
What is the primary function of osteocytes in bone cell action?
Bone remodeling
Which type of bone is primarily non-living material?
Cortical bone
What is the main component of the bone matrix?
Collagen
What is the primary function of osteoclasts in bone cell action?
Resorb (dissolve) bone
What is the primary role of vitamin D in the body?
Enhance calcium absorption
What is the bioavailability of a nutrient?
The rate at which a nutrient is absorbed and used by the body
What is the primary function of glucocorticoids in bone cell action?
Resorb (dissolve) bone
Study Notes
Bone Building Nutrients
- Factors affecting bioavailability of nutrients include digestive efficiency, nutritional status, concurrent intake of inhibitors/promoters, food preparation methods, and nutrient source.
- Bones are made up of trabecular bone (spongy) and cortical bone (compact), with the majority being non-living material.
- The matrix of bones consists of collagen and other proteins, with a mineral coating that includes calcium, phosphate, carbonate, and other ions.
- There are four main types of bone cells: lining cells, osteoblasts, osteoclasts, and osteocytes.
- Bone cell action is controlled by hormones, including parathyroid hormone, calcitriol, glucocorticoids, growth factors, and calcitonin.
- Bone development occurs from birth to approximately age 20, with peak bone mass development between 12 and 30.
- Bone modeling and remodeling involve the continual resorption and replacement of bone, controlled by parathyroid hormone.
- Functions of bone include providing mechanical rigidity, protecting organs, permitting ambulation, acting as a homeostatic buffer, and serving as a storage form.
- Calcium is a key nutrient for bone formation and is mostly found in bones and teeth as hydroxyapatite or fluoroapatite.
- Blood calcium levels are tightly regulated by parathyroid hormone and calcitonin.
- Calcium absorption occurs through active transfer and passive diffusion, with factors such as vitamin D status, intestinal transit time, and age influencing absorption.
- Calcium is lost through urine, feces, sweat, skin sloughing, hair, and nails, with a total daily loss of approximately 60 mg.
- Good dietary sources of calcium include dairy products, plant-based alternatives, dried seaweed, almonds, spinach, and calcium-fortified foods.
Test your knowledge on factors that influence the absorption of calcium in the body. Explore topics such as vitamin D status, intestinal transit time, age, and calcium excretion. Learn how these factors affect the efficiency of calcium absorption and understand the importance of maintaining optimal levels of calcium in the body.
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