Calcium balance Flashcards

1
Q

What are the main players that control Ca flux

A

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

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2
Q

What are the key organs responsible for Calcium regulation

A

The parathyroid gland
The intestines
The kidneys
The bones
The skin

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3
Q

What form is Calcium found in bone

A

Hydroxyapatite

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4
Q

______ amount of calcium is released from bone

A

A very little

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5
Q

_____ is the major reservoir of Calcium in the body

A

Bones

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6
Q

Which type of bone has the most calcium turnover

A

Trabecular bone

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7
Q

What are the three types of bone cells

A

Osteoblasts
Osteoclasts
And Osteocytes

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8
Q

What is the primary composition of inorganic bone

A

Hydroxyapatite

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9
Q

What is the major composition of organic bone

A

Collagen

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10
Q

WHat is the osteoid made of

A

an organic matric made of collagen fibrils

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11
Q

What is responsible for synthesizing collagen to make up the osteon

A

Osteoblasts

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12
Q

What are the two mechanism for bone resorption

A

Osteocytic osteolysis
Osteoclasstic resorption

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13
Q

What is osteocytic osteolysis

A

The transfer of calcium from the canaliculi to the extracellular matrix

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14
Q

What cell is responsible for osteocytic osteolysis

A

Osteocytes

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15
Q

Between the two mechanisms of Calcium resorption which is the quickest

A

Osteocytic osteolysis

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16
Q

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

A

Osteocystic Osteolysis does not lead to a decrease in bone mass

17
Q

What cell is responsible Osteoclastic resorption

A

Osteoclasts

18
Q

What is the name of reduced bone density and mass

A

Osteoporosis

19
Q

How is the Parathyroid hormone related to calcium levels

A

Increasing it by increasing to bone resorption

20
Q

How is Calcitonin relate Ca levels

A

It decreases it by inhibiting resorption and increasing bone formation

21
Q

How is vitamin D related to Ca levels

A

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

22
Q

How is Vitamin D synthesized and in what form

A

Vitamin D is synthesized in the skin in an inactive form

23
Q

How is Vitamin D activated

A

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

24
Q

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

A

1α-hydroxylase

25
\_\_\_\_\_\_ inhibit 1α- hydroxylase
Phosphates
26
\_\_\_\_\_\_\_ stimulates 1α- hydroxylase
Parathyroid Hormone
27
How does Vitamin D increase Ca absorption in the intestine
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
28
How does vitamin D cause Bone resorption
They act on osteoblasts which then signal osteoclasts for resorption
29
What is the difference between primary and secondary hyperthyroidism
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
30
What are the main causes of the Secondary hyperparathyroidism
Renal failure lading to oversecretion of Ca Decreased receptors for Ca and Vit D3 Increased phosphur leading to in uremia induced parathyroid gland hyperplasia
31