7.6 Regulating blood calcium levels

Question 1

What is osteoid made of?

Answer 1

Collagen fibers- the organic part of bone.

Question 2

What are things that calcium is necessary for?

Answer 2

Muscle contractions, exocytosis of molecules from cells (including nerve cells), stimulating of the heart by pacemaker cells, and blood clotting.

Question 3

What are two major hormones that help regular blood calcium levels?

Answer 3

Calcitriol

Parathyroid hormone

Question 4

What are the steps of activating vitamin D to calcitriol?

Answer 4

1) Ultraviolet light converts the precursor molecule of keratinocytes to Vitamin D3 which is released into the blood.
2) Vitamin D3 is circulated in the blood and passes through blood vessels into the liver where it is converted into calcidiol.
3) Calcidiol is circulated into the blood and is converted into calcitriol (active form of Vitamin D) in the kidneys. Parathyroid hormone in the kidneys increases the rate of this final enzymatic pathway in the kidneys.

Question 5

What does calcitriol do?

Answer 5

Stimulates the calcium absorption from the small intestines int to he blood.

Question 6

What do PTH (parathyroid hormone) and calcitriol do together?

Answer 6

1) Increase the re-uptake of calcium from the bone into the blood stream by stimulating osteoclast activity.
2) Stimulate the kidneys to excrete less calcium in the urine.
3) Calcitiriol encourages the blood to absorb more calcium from the small intestines.

Question 7

What does calcitonin do and where does it come from?

Answer 7

Comes from the thyroid gland

Inhibits osteoclast activity in response to high blood calcium levels and exercise.

Question 8

Osteomalacia

Answer 8

Rickets- Insufficient bone mineralization
Osteoid made but calcium salts not deposited.
Usually caused by inadequate nutrition or lack of Vitamin D ( often from kids one getting outside enough.)

Question 9

Define arthorlogy

Answer 9

the study of joints