ESR[036]: Endocrine Control of Calcium Homeostasis

Question 1

Answer 1

Question 2

Which types(s) of serum Ca 2+ is biologically active ??

Answer 2

Only free, ionized Ca 2 + is biologically active

Question 3

……are the differentiated bone forming cells and secrete bone matrix on which Ca ++and PO4 precipitate.

Answer 3

Osteoblasts

Question 4

Inorganic bone is composed of….. & organic matrix is composed primarily of……

Answer 4

hydroxyapatite , collagen

Question 5

Alkaline phosphatase and osteocalcin plasma levels are indicators of…….. activity

Answer 5

osteoblast

Question 6

Requirements of mineralization ?

Answer 6

• Requires adequate Calcium and phosphate

• Dependent on Vitamin D

• Alkaline phosphatase and osteocalcin play roles in bone formation

Question 7

Two groups of people with - and
+ calcium balances ?

Answer 7

• In growing children: intestinal absorption > renal excretion (+ve balance) ~10mmol/day &raquo_space; ↑calcium content by 400 mg/day

• In post-menopausal women, output (from bone)&raquo_space; input&raquo_space; negative Ca 2 + balance

Question 8

Answer 8

Question 9

Answer 9

Question 10

The blood supply to the parathyroid glands is from the……. arteries

Answer 10

thyroid

Question 11

Structure of Parathyroid Hormone ?

Answer 11

is an 84 amino acid single chain protein, released from th chief cell in the parathyroid glands.

Question 12

Parathyroid Hormone secretion is regulated via vitamin …

Answer 12

vitamin D

Question 13

Other substances that affect PTH release ?
And how ?

Answer 13

Question 14

The main PTH actions ?

Answer 14

Question 15

Tissue distribution of Calcium Sensing Receptor ?

Answer 15

Question 16

How does the parathyroid sense ECF Ca2+concentration changes ?
Elaborate

Answer 16

Question 17

How does vitamin D affect PTH ?

Answer 17

1,25-(OH)2 -D inhibits PTH gene expression, providing another level of feedback control of PTH.

Question 18

Effects of PO4 on PTH regulation ?

Answer 18

Despite close connection between Ca 2+and PO4, no direct control of PTH is exerted by phosphate levels.

Question 19

Answer 19

Question 20

Answer 20

Question 21

Answer 21

Question 22

Types of Hypoparathyroidism ?

Answer 22

1) Iatrogenic: accidental removal of parathyroid glands during thyroid surgery

2) Idiopathic: failure of parathyroid hormone secretion of unknown cause&raquo_space; Low circulating PTH, hypocalcaemia and hyperphosphataemia

3) Pseudohypoparathyroidism: tissue resistance to PTH action due to mutation in PTH receptor or decreased receptor expression

Question 23

Pseudohypoparathyroidism pathogenesis ?

Answer 23

Question 24

main indications of Parathyroidectomy ?

Answer 24

therapy- resistant hypercalcaemia and/or hyperphosphatemia.

Question 25

Question 26

Answer 26

Question 27

Defects in the neural crest-derived APUD cells give rise to……., whereas increased proliferation of those APUD cells not derived from the neural crest give rise to…...

Answer 27

multiple endocrine neoplasia (MEN)2 ,, MEN1

Question 28

Answer 28

Question 29

Answer 29

Question 30

Answer 30

Question 31

Explain steps of Vitamin D synthethis

Answer 31

Question 32

effect of vit D on transcription ?

Answer 32

Question 33

Factors (other than calcium) that influence 1α-hydroxylase activity ?

Answer 33

Question 34

How does vitamin D3 circulate ?

Answer 34

Question 35

Answer 35

Question 36

Effect of Calcitriol on 24-hydroxylase and 1αhydroxylase ?

Answer 36

• Calcitriol induces 24-hydroxylase and represses 1αhydroxylase

Question 37

Effect of PTH on 1αhydroxylase ? And what’s it’s significance ?

Answer 37

Question 38

Effect of Calcitonin , cortisol, oestrogen and prolactin on 1α-hydroxylase activity ?

Answer 38

Calcitonin suppresses 1α-hydroxylase, whereas growth h cortisol, oestrogen and prolactin increase its activity

Question 39

Answer 39

Question 40

Answer 40

Question 41

Answer 41

Question 42

Answer 42

Question 43

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Question 44

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Question 45

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Question 46

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Question 47

Answer 47