Deck 68: Calcium and Phosphorus Homeostasis Ii

Question 1

PTH

A) Increases calcium reabsorption but no t ph os ph ate re ab so rptio n in the dist al tu bu le
B) Increases bo th c alc ium an d p ho sp ha te r ea bs or ptio n in the dis tal tu bu le
C) Increases bo th c alc ium an d p ho sp ha te r ea bs or ptio n in the pro xim al tu bu le
D) Inh ibits bo th c alc ium an d p ho sp ha te r ea bs or ptio n in the dis tal tu bu le
E) Increases calcium rea bsorption and inhibits phosphate reabsorption in both proximal and dis tal tu bu le

Answer 1

A

Question 2

The m os t like ly fun ctio n o f c alb ind in is

A) Increase calcium diffusion across the enterocyte's cytosol
B) Activate ECaC
C) Bu ffer [C a] so that it doe s no t harm the e ntero cyte
D) Activate PMCA
E) Both A and C are true

Answer 2

E

Question 3

Osteoblasts do all of the following EXCEPT

A) Form the osteoid, or organic matrix of bone
B) Recruit osteoclasts from stem cells in the blood
C) Secrete M-CSF (macrophage colony stimulating factor) in response to PTH
D) Secrete osteoprotegrerin to block preosteoclast binding
E) Fo rm reso rptio n ca na ls

Answer 3

E

Question 4

The target bone cell for CT is the

A) Osteoblast
B) Osteoclast
C) Os teoc yte
D) Ch rond roc yte
E) Both A and C are true

Question 5

Recruitment of osteoclasts from hem apoetic precrusors in the blood is stimulated by

A) PT H an d c alc iton in
B) PTH alone
C) Calcitonin alone
D) PTH and 1,25 dihydroxycholecalciferol
E) CT and 1,25 dihydroxycholecalciferol

Question 6

CT rece ptors on o steo clas ts

A) Operate through a Gs mechanism
B) Signal through a Gq-coupled receptor
C) Se al o ff a n a re a b y bin din g to os teo ca lcin
D) Require 1,25 dihydroxycholecalciferol for activation
E) Activate bone resorption

Question 7

PTH

A) Increases calcium reabsorption and inh ibits ph os ph ate rea bs or ptio n in the pro xim al tu bu le
B) Increases bo th c alc ium an d p ho sp ha te r ea bs or ptio n in the dis tal tu bu le
C) Inh ibits bo th c alciu m and ph os ph ate re ab so rptio n in the pro xim al tu bu le
D) Increases bo th c alc ium an d p ho sp ha te r ea bs or ptio n in the dis tal tu bu le
E) Increases calcium reabso rption and inhibits phosphate reabsorption in both proximal and dis tal tu bu le

Question 8

The only hormone that significantly alters calcium and pho sph ate rea bs or ptio n in the pro xim al tu bu le is

A) ADH
B) PTH
C) CT
D) 1,25 dihydroxy cholecalciferol
E) Aldosterone

Question 9

Giant, multinucleated cells that resorb bone are called

A) Os teob lasts
C) Oste oclasts
D) Osteocytes
E) Chondrocytes
F) Ch ond robla sts

Question 10

Receptors for vitamin D

A) Bind to vitamin D-response e lements of DNA
B) Are present in intestine, bone and kidney
C) Activate a gene for calbindin in the intestine
D) Bind 1,25 dihydroxycholecalciferol
E) All of the above

Question 11

Os teoc lasts

A) Lay down the organic matrix of bone
B) Resorb just the mineral of bone
C) Resorb mineral and organic matrix of bone
D) Mineralize normal organic matrix of bone
E) Originate from osteocytes

Question 12

Calcium entry across the brush border mem brane of enterocytes is mediated by

A) Passive permeability through the lipid bilayer
B) Fa cilita ted diff us ion by c alb ind in
C) The epithelial calcium channel, ECaC
D) Ca-Cl2 co-transporter
E) PMCA

Question 13

The shaft of a long bone is called the

A) Ep iph ysis
B) Periosteum
C) Dia ph ysis
D) C on dyle
E) Endosteum

Question 14

Cells that are embedded deep in bone are called

A) Os teob lasts
C) Os teoc lasts
D) Osteocytes
E) Chondrocytes
F) Ch ond robla sts

Question 15

Cells that line the surfaces of bone and lay down organic matrix are called

A) Oste oblasts
C) Os teoc lasts
D) Osteocytes
E) Chondrocytes
F) C an na licu li

Question 16

The organic matrix of bone contains all of the following EXCEPT

A) Collagen type I
B) O ste oc alc in
C) M atr ix G LA pro tein
D) Vitr on ec tin
E) Ca lbin din

Question 17

Phosphate absorption from the intestine is directly controlled solely by

A) PTH
B) CT
C) Cholecalciferol
D) 25 hydroxycholecalciferol
E) 1,25 dihydroxycholecalciferol

Question 18

The target bone cell for PTH is the

A) Osteoblast
B) Osteoclast
C) Os teoc yte
D) Ch rond roc yte
E) Both A and C are true

Question 19

The m ain eff ec t of CT is

A) Increasing calcium and phosphate absorption from the intestines'
B) Increasing calcium and phosphate reabsorption from the kidney
C) Decreasing calcium and phosphate resorption from bone
D) Decreasing calcium and phosphate reabsorption from the kidney
E) Decreasing calcium and phosphate absorption from the intestines