Module 9.6 Endocrine Control of Calcium Metabolism

Question 1

Calcium (Ca2+) plays an important role in the body. It is involved in

• _________
• _________
• _________ of secretory products
• maintenance of _________
• ________
• ________

Answer 1

• neuromuscular excitability,
• muscle contraction,
• exocytosis of secretory products,
• maintenance of tight junctions,
• blood clotting, and
• bone formation

Question 2

• About 99% of the body’s calcium is stored in ___\_and ___\_
• about 0.9% is stored in ____.
• The remainder (<0.1%) of the body’s calcium is present in the _______\_and is regulated by hormones that influence _______\_ in the urinary, digestive, and skeletal systems

Answer 2

• About 99% of the body’s calcium is stored in bone and teeth
• about 0.9% is stored in soft tissues.
• The remainder (<0.1%) of the body’s calcium is present in the extracellular fluid (ECF) and is regulated by hormones that influence calcium metabolism in the urinary, digestive, and skeletal systems

Question 3

What are the three hormones that influence calcium metabolism in the urinary, digestive, and skeletal systems?

Answer 3

1. parathyroid hormone (PTH),
2. calcitriol (the active form of vitamin D), and
3. calcitonin

Question 4

The ________, which are located on the posterior surface of the thyroid gland, are responsible for the secretion of PTH

Answer 4

The parathyroid glands, which are located on the posterior surface of the thyroid gland, are responsible for the secretion of PTH

Question 5

The parathyroid glands, which are located on the ______ surface of the _____ gland, are responsible for the secretion of ____

Answer 5

The parathyroid glands, which are located on the posterior surface of the thyroid gland, are responsible for the secretion of Parathyroid Hormone (PTH)

Question 6

What stimulates the release of Parathyroid Hormone (PTH)?

Answer 6

PTH is released in response to a decrease in plasma concentrations of calcium

Question 7

Parathyroid Hormone (PTH) acts directly on what three body parts and what is the effect?

Answer 7

acts directly on the bone, intestine, and kidneys to increase plasma concentrations of calcium

Question 8

In the bone, Parathyroid Hormone (PTH) stimulates ____\_movement into the ___\_ from bone ___\_ and through _______ (removal)

Answer 8

In the bone, Parathyroid Hormone (PTH) stimulates calcium movement into the plasma from bone fluid and through bone resorption (removal)

Question 9

In the kidneys, PTH increases ________\_and increases the activation of _______\_.

Answer 9

In the kidneys, PTH increases calcium reabsorption and increases the activation of vitamin D.

Question 10

What is hypercalcemia?

What is it caused by?

Answer 10

High levels of Calcium.

Caused by Parathyroid Hormone hypersecretion (hyperparathyroidism)

Question 11

What are 5 symptoms of Hyperparathyroidism (hypersecretion of PTH)?

Answer 11

1. Muscle weakness
2. Neurological Disorders
3. Cardiac and Digestive system disturbances
4. Bone Thinning
5. Increased formation of kidney stones

Question 12

What is hypocalcemia and what does it result from?

Answer 12

Hypocalcemia is low levels of plasma calcium.

Caused from (Parathyroid hormone) PTH hyposecretion (hypoparathyroidism)

Question 13

What are two symptoms of Parathyroid Hormone (PTH) hyposecretion?

Answer 13

1. increased neuromuscular excitability and
2. altered mental functioning.

Question 14

Vitamin D is obtained both from the ___\_and from the ___\_ and must be activated by _____\_and _______\_ enzymes

Answer 14

Vitamin D is obtained both from the diet and from the skin and must be activated by hepatic (liver) and renal (kidney) enzymes

Question 15

The active form of vitamin D is called?

Answer 15

calcitriol

Question 16

What is the effect of Calcitriol?

Answer 16

Calcitriol increases plasma concentrations of calcium

Question 17

How does Calcitriol increase the plasma [calcium]?

Answer 17

• By increasing calcium absorption from the digestive system and
• by increasing the bone’s responsiveness to parathyroid hormone (PTH)

Question 18

A deficiency in vitamin D impairs the ____\_absorption of ____\_ and leads to _______\_, which in children is a condition called ___\_ and in adults is a condition called ______\_

Answer 18

A deficiency in vitamin D impairs the intestinal absorption of calcium and leads to demineralized bone, which in children is a condition called rickets and in adults is a condition called osteomalacia

Question 19

A deficiency in vitamin D impairs the intestinal absorption of calcium and leads to demineralized bone, which in children is a condition called ___\_and in adults is a condition called ______\_

Answer 19

A deficiency in vitamin D impairs the intestinal absorption of calcium and leads to demineralized bone, which in children is a condition called rickets and in adults is a condition called osteomalacia

Question 20

Figure 9.6.1 – Interactions of parathyroid hormone (PTH) and vitamin D in the control of plasma calcium.

Answer 20

Figure 9.6.1 – Interactions of parathyroid hormone (PTH) and vitamin D in the control of plasma calcium.

Question 21

In contrast to PTH and calcitriol, calcitonin is secreted from the ______ cells of the ______ gland in response to __________________

Answer 21

In contrast to PTH and calcitriol, calcitonin is secreted from the C cells of the thyroid gland in response to increased plasma concentrations of calcium

Question 22

Calcitonin decreases ______________\_ by

• decreasing the movement of calcium from the _____\_ and
• by decreasing ______\_

Answer 22

Calcitonin decreases plasma concentrations of calcium by

• decreasing the movement of calcium from the bone fluid and
• by decreasing bone resorption

Question 23

_______\_ decreases plasma concentrations of calcium by

• decreasing the movement of calcium from the bone fluid and
• by decreasing bone resorption

Answer 23

Calcitonin decreases plasma concentrations of calcium by

• decreasing the movement of calcium from the bone fluid and
• by decreasing bone resorption