Physiology

Question 1

How often is spongy bone replaced?

Answer 1

Every 3-4 years

Question 2

How often is compact bone replaced?

Answer 2

Every 10 years

Question 3

Describe the 2 steps involved in bone remodeling

Answer 3

1. Bone resorption - by osteoclasts

2. Bone formation - by osteoblasts

Question 4

What is the function of parathyroid hormone (PTH)? Where is it produced?

Answer 4

In response to LOW serum calcium, PTH INCREASES bone resorption to raise serum calcium.

PTH is produced by the parathyroid glands.

Question 5

What is the function of calcitonin? Where is it produced?

Answer 5

In response to HIGH serum calcium, calcitonin opposes the action of PTH to decrease bone resorption.

It is produced by c-cells in the thyroid.

Question 6

In which part of the kidney does PTH exert its effects?

Answer 6

The early DCT is a major site where parathyroid hormone (PTH) stimulates reabsorption of Ca2+.

The amount of Ca2+ reabsorption in the early DCT varies depending on the body’s needs.