7.6 Flashcards

1
Q

EC Ca++ conc

A
Free= 1-1.3 mM
Total= 2.2-2.6 mM
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2
Q

IC Ca++ conc

A

100 nM

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3
Q

How Ca++ travels in the blood?

A

Ionized form= 45%
Bound to proteins= 45%
Complex with anions= 10%

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4
Q

What happens when there are more Albumin/ Phosphate in the blood?

A

Less Ca++ is free

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5
Q

What happens when pH goes down?

A

H+ binds to Albumin -> increasing free Ca

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6
Q

What synthesize PTH

A

Chief cells in the parathyroid glands

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7
Q

Describe PTH secretion

A

preproPTH -> proPTH -> PTH (84AA)

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8
Q

What evokes the secretion of PTH?

A

Ca-Sensing-Receptors (CaSR) present on chief cells

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9
Q

Ca-Sensing-Receptors (CaSR)

Way of action

A

Gq detect high Ca -> IC Ca signal -> inhibition of vesicle fusion

***also has Gi activity

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10
Q

What is the result of Ca-Sensing-Receptors (CaSR) mutation?

A

Familial Hypercalemic Hypocalciuria

Decreased affinity of Ca-Sensing-Receptors to Ca

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11
Q

What will higher phosphate cause

A

Less free Ca

So more PTH secretion

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12
Q

How vit.D affect PTH

A

Decrease secretion
By increasing CaSR expression
By Direct PTH gene inhibition

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13
Q

Long term vit D def. will cause

A

Rickets= deformation of long bones bcs there is less Ca and Pi absorption from the GI

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14
Q

What secretes clacitonin

A

Parafollicular C cells of thyroid

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15
Q

Action of Calcitonin

A

Decrease Ca levels by inhibiting Osteoclasts so increasing bone formation

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16
Q

What increase secretion of Calcitonin

A

High Ca

More than 1.3 mM

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17
Q

Which disease can exogenous Calcitonin treat

A

Paget’s Disease

Disorder of overactive OsteoClasts

18
Q

2 types of bones

A

Compact- 80% of the long bones

Spongy- 20% of all bones

19
Q

Location of spongy bones

A

Vertebral
Neck of long bones
Bone cavity

20
Q

Special thing of spongy bones

A

High surface area so high turnover of formation and resorption of bone

21
Q

Osteoblast origin

A

Fibroblasts

22
Q

Secretory proteins of osteoblasts

A

Collagen type 1
Osteocalcin
Osteonectin
Alkaline phosphate

23
Q

Osteolacin job

A

Binds Ca and hydroxyapetite

24
Q

Osteonectin job

A

Same as osteolacin

25
Alkaline phosphate job
Role in the formation of Hydroxyapetits
26
Regulatory proteins of Osteoblasts
RANK Ligand | OPG
27
Catabolic enzymes of Osteoblasts
Collagenase | Gelatinase
28
Phases of bone formation
Osteoid formation | Mineralization
29
How much time does osteoid formation takes
10-14 days
30
What happens during osteoid formation
Creation of protein matrix of bones
31
What does osteoid gives us
Site for nucleation and precipitation of hydroxyapetite
32
Duration of mineralization
Couple of weeks
33
What happens during mineralization
Pi groups are released for the formation of hydroxyapatite
34
Where do osteoClast comes from
Haematopoietic cell line
35
What do osteoclast activation requires
M-CSF RANK Ligand IL-6 (cytokine)
36
What regulates bone resorption
1. PTH, Calcitriol 2. Calcitonin 3. Glucocorticoids 4. Estrogens 5. Tumors
37
Job of PTH and calcitriol in bone resorption
Act on osteoblasts ->RANK -> osteoclast activation
38
Job of OPG
Acts on osteoclast and decrease their activity | It blocks the RANK R
39
What determines osteoclast activity?
RANK/OPG ratio High- increase osteoclast activity Low- decreases
40
Calcitonin acts on osteoclasts?
Inhibition
41
Glucocorticoids action on bones?
Acts on osteoblasts | Increase RANK/OPG ratio
42
Estrogens action on bones?
Decrease RANK/OPG ratio