Biological Sciences 23

Question 1

what does hypocalcemia

Answer 1

nervous system excitement and tetany

can cause seizures

Question 2

why does hypocalcemia cause nervous system excitement

Answer 2

increases neuronal membrane permeability to sodium ions

Question 3

where does the first time of tetany occur?

Answer 3

hand

carpopedal spasm

Question 4

at what level of Calicum does it become lethal?

Answer 4

4mg/dl

Question 5

when does tetany occur?

Answer 5

when calcium levels drop below 6 mg/dl

Question 6

how is calcium deposited thru out body

Answer 6

0.1% in ECF
1% in organelles
rest in bones

Question 7

how much Ca is excreted in feces per day?

Answer 7

900 mg/day

Question 8

if we have excess calcium, where can we put it?

Answer 8

in the bones

Question 9

administration of PTH causes

Answer 9

rapid loss of phosphate in urine

increased reabsorption of calcium

sacrificing P for Ca

Question 10

True or False?

osteoclasts do not have receptors for PTH

Answer 10

true

Question 11

mechanism of PTH action on osteoclast

Answer 11

1. PTH acts on osteoblast
2. osteoblast recruits monocytes to make osteoclasts
3. osteoblasts produce ostoprotegrin ligand
4. ostoprotegrin ligand activates receptors on pre-osteoclast cell (monocyte)

Question 12

what produces the osteoprotegrin ligand?

Answer 12

osteoblast

Question 13

what is the signal of the PTH/osteoclast?

Answer 13

protegrin

Question 14

active form of vitamin D

Answer 14

1,25 dihydroxycholecalciferol

Question 15

effects of vitamin D

Answer 15

1. causes intestine, kidneys, bones to increase calcium and phosphate absorption into ECF
2. contributes to feedback regulation

Question 16

where are vitamin D receptors found?

Answer 16

most cell son the body

near the nuclei

Question 17

vitamin D receptor characteristics

Answer 17

intracellular

has hormone binding domain

has DNA binding domain

Question 18

activation of vitamin D occurs where? by what?

Answer 18

kidney

by PTH

Question 19

form of vitamin D in skin

Answer 19

vitamin D3 (goes to liver)

Question 20

form of vitamin D in liver

Answer 20

25-hydroxycholecalciferol

goes to kidney

Question 21

function of vitamin D

Answer 21

promotes intestinal absorption of calcium

Question 22

how does vitamin D preform its funciotn?

Answer 22

increasing calbindin formation on gut epithelial cells (remains there for weeks after vitamin D removal)

calbindin transports calcium into cell

Question 23

calcium moves thru basolater membrane by

Answer 23

facilitated diffusion