Inorganic nutrients I

Question 1

Calcium absorption characteristics?

Answer 1

Relies on:

• Calcium entry through TRPV6
• intracellular transport by calbindin
• cellular extrusion via NCX or PMCA

Up-regulated by 1,25(OH) vitamin D

Question 2

Function of 1, 25(OH) vitamin D

Answer 2

Increases intestinal calcium absorption and accelerates calcium absorption from GI

Question 3

Function of PTH?

Answer 3

Liberates calcium from bone, increasing blood calcium

Stimulates vit D conversion to the active form

Question 4

Function of Calcitonin?

Answer 4

Increases deposition of calcium, lowering blood calcium

Question 5

What occurs in a deficiency of calcium?

Answer 5

Osteoporosis
Rickets (in children) / Malacia (in adults)
Tetany

Question 6

Phosphorus absorption characteristics?

Answer 6

Not biologically available, so needs exog. phytase

Is released as inorganic phosphate

Absorption stimulated by Vitamin D

Absorption impaired by magnesium and calcium

Question 7

Magnesium absorption characteristics?

Answer 7

Modulated by vitamin D and PTH

Question 8

Iodine absorption and fxns?

Answer 8

Absorbed in stomach and small intestine

Involved in the synthesis of thyroid hormones T4 and T3

Question 9

Iodine deficiency characteristics

Answer 9

Goiter: decreased T3 levels due to decreased iodine levels leads to an increase in TSH, stimulating growth and proliferation of the thyroid gland

Cretinism: is congenital

Question 10

Zinc absorption characteristics?

Answer 10

Main import protein is zip4

Intracellularly bound to metallothionein (MT)

Main export protein is znt1

Transported by albumin, after leaving via znt1

Question 11

Zinc deficiency?

Answer 11

Seen in institutionalized patients and the elderly

Clinical manifestations: impaired wound healing, oral ulcerations, stomatitis, diminished taste

Question 12

Acrodermatitis Enteropathica (AEZ)

Answer 12

Caused by mutation of the zip4 intestinal zinc transporter

Sx: dermatitis, alopecia
Tx: give them more zinc!