12 Questions
Which of the following is NOT a biological role of calcium?
Immune system regulation
In the plasma, blood calcium is present in 3 fractions, except:
Intracellularly in red blood cells
Which of the following factors diminishes intestinal transport of calcium?
Adrenal glucocorticoids
What happens to any extra calcium absorbed from the intestine in a normal adult?
Excreted in the urine
What is the influence of Vitamin D on calcium absorption?
Increase in calcium absorption
How do organic acids, lactose, and basic amino acids in the diet affect calcium absorption?
Increase calcium absorption
What dietary factor decreases the absorption of calcium?
High concentration of magnesium
How does a high calcium intake affect its absorption?
Decreases the percentage of absorption
What is the main consequence of a decrease in ionized calcium in the serum?
Tetany
How much calcium, on average, is absorbed from the diet and how much is excreted as fecal calcium?
75% absorbed, 25% excreted
What is the primary route of excretion for calcium in the body?
Urine
How does vigorous physical exercise affect calcium loss in the body?
Increases urinary calcium excretion
Study Notes
Calcium Roles and Absorption
- Calcium has various biological roles, excluding:
- Blood clotting
- In the plasma, blood calcium is present in 3 fractions, excluding:
- Albumin-bound fraction
Calcium Absorption
- Factors that diminish intestinal transport of calcium:
- Oxalic acid and phytic acid
- In a normal adult, extra calcium absorbed from the intestine is:
- Deposited in bones
- Vitamin D's influence on calcium absorption:
- Increases calcium absorption
- Organic acids, lactose, and basic amino acids in the diet:
- Increase calcium absorption
- Dietary factor that decreases calcium absorption:
- Phosphorus
- High calcium intake's effect on its absorption:
- Decreases absorption efficiency
- Main consequence of a decrease in ionized calcium in the serum:
- Tetany (muscle cramps)
Calcium Balance and Excretion
- Average calcium absorbed from the diet:
- 200-300 mg/day
- Average calcium excreted as fecal calcium:
- 150-200 mg/day
- Primary route of excretion for calcium in the body:
- Kidneys (via urine)
- Vigorous physical exercise's effect on calcium loss:
- Increases calcium loss in the body, particularly in the urine
This quiz covers the factors influencing calcium absorption, including the effects of parathyroid hormone, adrenal glucocorticoids, aging, and kidney threshold. It also tests knowledge on the excretion of excess calcium in a normal adult.
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