PTH & Calcitonin

PTH's affect on the intestine?

Increased calcium absorption

PTH's affect on bone?

Increased release of calcium and phosphate from bone

PTH binds to *osteoblasts* and causes what two things to occur?

1. Decrease osteoblast activity 2. Increase osteoclast activity by releasing a chemical called "osteoclast stimulating factor" (AKA, IL-1).

Effect of Calcitonin on osteoclast and osteoblast activity?

1. Decreased osteoclast activity 2. Increased osteoblast activity

Effect of PTH on osteoclast and osteoblast activity?

1. Increased osteoclast activity 2. Decreased osteoblast activity

What are the three organs that PTH raises calcium levels?

Bone, Kidneys, and Intestine

Acts to decrease blood calcium levels

Calcitonin

Released by the C Cells of the thyroid gland in response to high blood calcium

Calcitonin

Increased osteoblast activity

Calcitonin (calcium from blood and deposited in the bone matrix)

Decreased osteoclast activity

Calcitonin (leading to decreased breakdown of bone matrix and decreased calcium being released into the blood)

PTH's affect on the kidneys?

Decreased urinary calcium excretion and increased excretion of phosphate.

Acts to increase calcium and decrease phosphate

PTH

Released when blood calcium levels are low

PTH

Increased osteoclast activity

PTH (leading to increased breakdown of bone matrix and increased amount of calcium being released into the blood)

Decreased osteoblast activity

PTH (less calcium from the blood being taken to make new bone)

PTH and Calcitonin affect bone _____ and _____.

Resorption and Deposition