Minerals

Question 1

Biochemical roles of Ca2+

Answer 1

1. regulate excitation-contraction coupling.
2. Stimulus secretion coupling
3. Blood clotting
   - activates PKC –> Activ. PLA
4. Membrane excitability
5. cellular permeability

Question 2

Narrow limits of calcium + phosphate

Answer 2

Ca: 8-10mg/dl

Phosphate: 3-4 mg/dl
- PO43-

Question 3

Majority of body calcium is found in the form of ______.

Answer 3

hydroxyapatite

Question 4

How much calcium does the kidney filter per day?

Answer 4

10 g is filtered by kidney

9.83 g is reabsorbed back into blood

Question 5

Describe what happens to PTH levels in response to:
↓ Ca2+ :
↓ Mg2+ :
↓↓ Mg2+ : 
↑ PO43+ :

Answer 5

↓ Ca2+ : ↑ PTH
↓ Mg2+ : ↑ PTH
↓↓ Mg2+ : ↓ PTH
↑ PO43+ : ↑ PTH

(want to get rid of phosphate)

*note that PTH acts via cAMP signaling

Question 6

PTH leads to increase plasma Ca2+ how?
BOne
Kidney
GI tract

Answer 6

BOne:
rapid efflux of labile bone calcium

Kidney:
↑ ca reabsorp. fr distal tubule
↓ phosphate reab
↑ synth of 1,25 OH2 D

GI tract
indirect via vit D: ↑ ca absorp

Question 7

Net consequence of PTH action is to ____ serum Ca and ____ serum phosphate

Answer 7

↑ serum ca

↓ serum po4

Question 8

Calcitonin is a _____ hormone. It is secreted in response to elevated ______.

Answer 8

Peptide hormone

Serum ca
\+
GI hormones
1. gastrin
2. CCK
3. Secretin
4. Glucagon

(calcitonin keeps Ca2+ IN bone.)

Question 9

______, the active form of vitamin D is mostly transported in the blood bound to _____

Answer 9

1,25(OH)2 Vit D

Transcalciferin

Question 10

1,25(OH)2 Vit D effects on bone

Answer 10

sensitizes bone to PTH action

faciltate absorption of ca2+ from the gut

(small effect at ca2+ bone resorption into blood)

Question 11

effects of ketoconazole

Answer 11

inhibits desmolase

opp of ACTH

Question 12

High PTH will lead to increased levels of ________, which then acts on the GI tract to ________ absorption.

Answer 12

1,25(OH)2 Vit D

increase ca2+ absorption

(VIT D and PTH act synergisticallY)

Question 13

If plasma PO4 falls, ________ synthesis will then increase, which will act on the GI tract to _____.

Answer 13

1,25(OH)2 Vit D

increase PO4 absorption and return plasma phosphate lvls to normal.

Question 14

Lvls to expect with primary hyperparathyroidism

Answer 14

↑ PTH
leading to
↑ Ca2+ levels in plasma and urine
- leading to renal stones

Question 15

Sx of hypercalcemia

Answer 15

muscle weakness (decreases threshold)
GI disorders

Severe:
Bone demineralization
Bone pain
Fractures

Question 16

Secondary Hyper PT can result from any disorder where _______.

Answer 16

plasma ca2+ is low such as rickets and renal failure

Question 17

If you have ↓ in plasma ca DUE TO LACK OF PTH, what major symptoms can you expect?
→↓↑

Answer 17

Increase neuromuscular excitability → muscle cramps

Seizures

Mental changes

Question 18

In pts with renal disorders have low calcium levels, which form of Vit D do you give them?

Answer 18

Cant make 1,25 Vit D,

so give that: aka Calcitriol

Question 19

Most common cause of hypocalcemia in hospitalized pts

Answer 19

hypoproteinemia