Bone Profile

Question 1

functions of Ca2+

Answer 1

combines with phosphate ions to form calcium phosphate - inc bone rigidity and hardness of bones

also involved in signal transduction, blood clotting, muscle contraction, nerve activity, cofactor for enzymes i.e ferroportin

Question 2

what affects absorption of ca in the small intestine

Answer 2

conc in diet, pH, presence of activated vit D, parathyroid hormone, high protein diet, steatorrhoea, age

Question 3

what is the main antagonist of ca

Answer 3

magnesium

Question 4

how does vit D regulate ca

Answer 4

produced by adrenal gland and functions to stimulate intestinal calcium and phosphate absorbance and increase renal reabsorption of calcium

Question 5

how does parathyroid hormone regulate ca

Answer 5

increases blood calcium. increases intestinal absorption, increases osteoclast activity, increases renal reabsorption

MW 9500, 84 amino acids

Question 6

how does calcitonin regulate ca

Answer 6

produced by thyroid gland and lowers ca levels. inhibits osteoclast activity and decreases renal reabsorption of calcium

32 amino acid peptines, one disulphide bond
secreted by C cells of the thyroid in response to increased in ionised calcium

Question 7

where does PTH act

Answer 7

bone kidney intestine

Question 8

is PTH secretion negative or positive feedback mechanism

Answer 8

neg

Question 9

what is the name for activated vit D

Answer 9

1,25-dihydroxycholecalciferol

Question 10

where is vit D produced

Answer 10

adrenal glands - fat soluble

Question 11

what are the serum forms of calcium

Answer 11

1. ionised or free - 45/50% physiologically active
2. complexed - 5/10%
3. protein bound 40/50% - physiologically inactive

Question 12

what is total serum calcium

Answer 12

non diseased state total serum calcium of 2.4 mmol/L where 50% is protein bound to mostly albumin

binding is pH dependent - down in acidosis and up in alkalosis