M2-C1-L22 --> Physiology Of Bone

Front 1

Why is dietary calcium absorption poor?

Back 1

B/c it is in divalent form

Front 2

Vitamin D aids in absorption of what?

Back 2

Dietary calcium

Front 3

Where does the body get vitamin D from?

Back 3

Diet

UV light (via skin)

Front 4

What does the liver do in vitamin D processing?

Back 4

Converts vitamin D into 25-hydroxycholecalciferol

Front 5

What does the kidney do in vitamin D processing?

Back 5

Converts 25-hydroxycholecalciferol into the active or inactive form.

Front 6

What is the active form of vitamin D?

Back 6

1,25 dihydroxycholecalciferol

Front 7

What is the inactive form of vitamin D?

Back 7

24,25-dihydroxycholecalciferol

Front 8

What circumstances would promote the formation of 1,25 dihydroxycholecalciferol? x3

Back 8

Phosphate deficiency
Vitamin D deficiency
Calcium deficiency

Front 9

What circumstances would promote the formation of 24,25 dihydroxycholecalciferol? x3

Back 9

Phosphate excess
Active form present
Calcium excess

Front 10

1,25-dihydroxycholecalciferol:

- duration of effect
- activates what? x3

Back 10

Several weeks of CBP

Alkaline Phosphate
CBP
Calcium ATPase

Front 11

What inhibits the conversion of 25-hydroxycholecalciferol and where?

Back 11

It will inhibit itself if there is enough

In the liver

Front 12

What hormone activates the conversion of 1,25-dihydroxycholecalciferol in the kidney?

Back 12

Parathyroid hormone

Front 13

A high increase in plasma calcium ion concentration will inhibit what hormone?

Back 13

Parathyroid hormone

Front 14

50% of plasma calcium is in what form?

41% of plasma calcium is in what form?

9% of plasma calcium is in what form?

Back 14

Divalent form

Bound to protein

Bound to X

Front 15

Stress on bones will stimulate what?

Back 15

Bone remodeling

Front 16

What would promote PTH secretion?

Back 16

Low plasma calcium concentration

Front 17

What would inhibit PTH secretion?

Back 17

High plasma calcium concentration

Front 18

Parathyroid gland:

- where is it
- how many are there
- how many needed for normal function

Back 18

Behind thyroid

4

2

Front 19

What are the two cells in the parathyroid that differentiates it from the thyroid?

Back 19

Chief cells

Oxyphil cells

Front 20

PTH responds to what?

Back 20

Low calcium levels in plasma

Front 21

What is the MAIN hormone essential for calcium homeostasis?

Back 21

PTH

Front 22

What is the normal levels for calcium?

Back 22

9 - 10 mg/dl

Front 23

What hormone works in opposition to PTH?

Back 23

Calcitonin

Front 24

Parathyroid hypertrophy can result in what? x3

Back 24

Rickets
Pregnancy
Lactation

Front 25

Parathyroid atrophy can result in what? x3

Back 25

Vitamin D excess
Calcium excess
Bone absorption

Front 26

PTH plateaus in how many hours

Back 26

4 hours

Front 27

Calitonin plateaus in how many hours

Back 27

2 hours

Front 28

What are the direct effects of an increase in PTH secretion? x5

Back 28

1. Increase in Bone resorption
2. Increase in Active D vitamin
3. Increase in Urine Phosphate
4. Decrease in Urine Calcium
5. Decrease in Plasma Phosphate

Front 29

Answer

Back 29

Answer

Front 30

Hypoparathyroidism

- osteoclasts
- dangers x2
- treatment x2

Back 30

Becomes almost dormant

Tetany
Paralysis of laryngeal muscles
(possibly lethal if resp. effected)

PTH administration ($$)
Vitamin D and Calcium administration

Front 31

Hyperparathyroidism

- osteoclasts
- dangers x2
- treatment

Back 31

Elevated activity

Weak bones
Cystic areas of osteoclastic giant cell tumors

Surgical removal of tumors

Front 32

Calcitonin:

- Source
- Effective strength
- Mechanism x2

Back 32

Parafollicular cells of thyroid

Weak

Quick -> inhibits osteoclast activity

Slow -> inhibits osteoclast formation