Calcium balance

Question 1

What are the main players that control Ca flux

Answer 1

Calcitonin
Vitamin D3
Parathyroid Hormone,
Parathyroid-hormine related protein (PTHrP)

Question 2

What are the key organs responsible for Calcium regulation

Answer 2

The parathyroid gland
The intestines
The kidneys
The bones
The skin

Question 3

What form is Calcium found in bone

Answer 3

Hydroxyapatite

Question 4

______ amount of calcium is released from bone

Answer 4

A very little

Question 5

_____ is the major reservoir of Calcium in the body

Answer 5

Bones

Question 6

Which type of bone has the most calcium turnover

Answer 6

Trabecular bone

Question 7

What are the three types of bone cells

Answer 7

Osteoblasts
Osteoclasts
And Osteocytes

Question 8

What is the primary composition of inorganic bone

Answer 8

Hydroxyapatite

Question 9

What is the major composition of organic bone

Answer 9

Collagen

Question 10

WHat is the osteoid made of

Answer 10

an organic matric made of collagen fibrils

Question 11

What is responsible for synthesizing collagen to make up the osteon

Answer 11

Osteoblasts

Question 12

What are the two mechanism for bone resorption

Answer 12

Osteocytic osteolysis
Osteoclasstic resorption

Question 13

What is osteocytic osteolysis

Answer 13

The transfer of calcium from the canaliculi to the extracellular matrix

Question 14

What cell is responsible for osteocytic osteolysis

Answer 14

Osteocytes

Question 15

Between the two mechanisms of Calcium resorption which is the quickest

Answer 15

Osteocytic osteolysis

Question 16

Apart from the time taken what a major difference between osteocytic osteolysis and osteoclastic resorption

Answer 16

Osteocystic Osteolysis does not lead to a decrease in bone mass

Question 17

What cell is responsible Osteoclastic resorption

Answer 17

Osteoclasts

Question 18

What is the name of reduced bone density and mass

Answer 18

Osteoporosis

Question 19

How is the Parathyroid hormone related to calcium levels

Answer 19

Increasing it by increasing to bone resorption

Question 20

How is Calcitonin relate Ca levels

Answer 20

It decreases it by inhibiting resorption and increasing bone formation

Question 21

How is vitamin D related to Ca levels

Answer 21

Vitamin D leads to increased absorption of Ca from the Gut, increasing Bone resorption and Kidney resorption, henced inceased Ca

Question 22

How is Vitamin D synthesized and in what form

Answer 22

Vitamin D is synthesized in the skin in an inactive form

Question 23

How is Vitamin D activated

Answer 23

it is first hydroxylated in the liver and secondly in the Kidney to form 1,25-dihydroxy Vitamin D

Question 24

What enzyme is the main point of regulation of Vitamin D synthesis

Answer 24

1α-hydroxylase

Question 25

______ inhibit 1α- hydroxylase

Answer 25

Phosphates

Question 26

_______ stimulates 1α- hydroxylase

Answer 26

Parathyroid Hormone

Question 27

How does Vitamin D increase Ca absorption in the intestine

Answer 27

It binds to steroid receptors which increase the transcriptionn of certain proteins including Calcium Binding Proteins(CaBP)
This allow further absorption of Ca against a high Ca gradient from initial absorption

Question 28

How does vitamin D cause Bone resorption

Answer 28

They act on osteoblasts which then signal osteoclasts for resorption

Question 29

What is the difference between primary and secondary hyperthyroidism

Answer 29

Primary has to do with over production by the parathyroid gland, where as secondory has to do with lack of feedback inition of the parathyroid gland

Question 30

What are the main causes of the Secondary hyperparathyroidism

Answer 30

Renal failure lading to oversecretion of Ca
Decreased receptors for Ca and Vit D3
Increased phosphur leading to in uremia induced parathyroid gland hyperplasia