Calcium

Question 1

ECF functions

Answer 1

source of Ca in skeleton and cells
blood clotting
intracellular adhesion

Question 2

ICF functions

Answer 2

2nd messenger
(+) kinases for protein phosphorylation --> intracellular signaling.

muscle contraction, nerve transmission, glycogen metabolism, (+) enzyme, (+) hormones, vision, cell differentiation

Question 3

inc absorption

Answer 3

vit D adequacy, inc mucosal mass, Ca deficiency, pregnancy

Question 4

dec absorption

Answer 4

vit D deficiency, dec mucosal mass, menopause, dec stomach acid, fast SI transit, low estrogen.

excreted as fecal Ca, urinary excretion

Question 5

Phytic/ Oxalic acid

Answer 5

binds to Ca (-) Ca absorption

oxalic: spinach, collard greens, sweet potatoes, rhubarb, beans
phytic: whole grain products, wheat bran, beans, seeds, nuts, soy isolates

Question 6

Acid base balance

Answer 6

protein and cereal grains –> inc acid

fruits/ vegetables –> inc bicarbonate, red Ca loss (mg, K)

Question 7

Protein

Answer 7

(+) affects BMD, maintenance by inc IGF1 and intestinal Ca absorption, dec PTH

Question 8

dec serum Ca

Answer 8

inc PTH release, inc 1,25(OH)2D –> inc Ca absorption, reabsorption, resorption

Question 9

inc serum Ca

Answer 9

dec PTH release, dec 1,25(OH)2D –> dec Ca absorption, reabsorption, resorption

Question 10

Vitamin D

Answer 10

necessary for active transport of Ca across intestinal mucosa

Question 11

Phosphorus

Answer 11

bone mineral mostly Ca + Pi, adequate dietary Pi essential for bone

Question 12

Caffeine

Answer 12

short term inc in urinary Ca

Question 13

Sodium

Answer 13

inc NaCl –> inc urinary Ca excretion

inc 10 mg excretion for every 1000 mg dietary Na

Question 14

Potassium

Answer 14

(+) renal Ca retention, (Mg, K both have buffering effect)

Question 15

Calmodulin

Answer 15

(+) enzyme breakdown of glycogen.

Ca - Calmodulin –> conformational change –> bind and (+) kinases

Question 16

CaSRs

Answer 16

detects blood Ca concentrations, lets Ca act as extracellular first messenger –> calcitropic hormone

Question 17

calcitonin

Answer 17

lowers blood Ca (tones down blood Ca), secreted by parafollicular cells of thyroid.

mgmt for hypercalcemia or osteoporosis

Question 18

FGF23

Answer 18

regulates Pi concentration in plasma. secreted by osteocytes in response to high VD. inc Pi excretion, (-) 1 a hydroxylase

Question 19

TRVP6

Answer 19

transcellular absorption of Ca –> active transport

Question 20

Calbindin

Answer 20

1,25(OH)2D binds to nuclear receptor VDR –> RXR –> VDRE, inc Ca absorption in SI (Across cell)

Question 21

Calcium ATPase

Answer 21

absorption of Ca from intestinal cells to blood

Question 22

At risk

Answer 22

post menopause, amenorrheic/ female athlete triad, lactose intolerance, vegetarians

Question 23

osteoporosis

Answer 23

low Ca –> osteopenia –> osteoporosis

Question 24

HTN

Answer 24

inc Ca may possibly lower HTN risk.

women’s health study dec 2-4 mmHg SBP

Question 25

Cancer

Answer 25

inc Ca, dec risk of colon, rectum, inc risk of prostate

Question 26

weight management

Answer 26

inc Ca, dec weight. low Ca conc in fat cells by low PTH, VD --> inc fat breakdown, (-) fat accumulation. Ca from food might bind to small amounts of dietary fats in digestive tract, (-) absorption.

Question 27

toxicity

Answer 27

kidney stones, renal insufficiency, vascular/ soft tissue calcification, hypercalciuria, hyperparathyroidism can cause constipation, interfere w absorption of Fe and Zn maybe