Endo-Ca and Pi homeostasis

Question 1

PTH receptors (G-protein coupled Rs) are expressed in

Answer 1

bone and kidney

Question 2

major hormones that regulate Ca homeostasis

Answer 2

Calcitriol
PTH
Calcitonin

Question 3

PTH-R of bone expressed on

Answer 3

osteoblasts

Question 4

Factors that inhibits Calcitriol synthesis via negative feedback

Answer 4

impacts on calcitriol synth:

High Vit D level
H. ECF Ca
H. ECF pi

Question 5

Vit D impact on PTH

Answer 5

PTH secretion is inhibited by that

Question 6

Calcitriol effect

Answer 6

inc. plasma conc of BOTH Ca and Pi

Question 7

Ca salt content distribution in bone, ICF and ECF

Answer 7

99% in bone (hydrozyapetite crystals major form)

1% in ICF +ECF–> .1% ECF and 0.9 ICF

Question 8

leads to decreased PTH secretion

Answer 8

an increase in plasma Ca

Question 9

Which form of the Ca is affected by hypo and hypercalcemia

Answer 9

ionized form

Question 10

Controls Ca2+ homeostasis

Answer 10

plasma Ca

Question 11

DBP

transport protein

Answer 11

VitD-Binding protein

Question 12

Cells with Ca-sensing plasma membrane R (Ca-R)

Answer 12

PTH-secreting cells
Calcitonin secreting cells
kidney and intestinal epithelium

Bone ? unclear

Question 13

Calcitriol synth. stimulated by

Answer 13

impacts on Calcitriol synthesis:

PTH
L. ECF Ca
L. ECF Pi

Question 14

T/F

ionized [Ca] pools in the ECF and ICF are at equilibrium

Answer 14

T

Question 15

Rapid PTH responses of kidney cells expressing PTH-R

Answer 15

dec. Ca excretion with urine (within min)

Inc phosphate excretion with urine (within minutes)

Question 16

PTH effect

Answer 16

inc Ca- dec Pi

Question 17

The calcium salt contents of:
Bone
Body fluids: ECF and ICF

Answer 17

Bone- 99%

Body fluid: 1% ( 0.1% ECF and 0.9% ICF)

Question 18

Percent distribution of calcitriol

Answer 18

99.6% and metabolites bound to Vit-D binding proteins (DBP)

and 0.4% as free form

Question 19

indirect PTH inhibition bu Vit D

Answer 19

• feedback (through plasma conc of Ca)

Question 20

PTH secretion is regulated bu

Answer 20

ionized plasma Ca

Question 21

The active form of Vit D and its classification

Answer 21

Calcitriol

classified as steroid hormone

Question 22

Rapid Ca mobilization response to PTH

Answer 22

From Soluble form

Question 23

besides calcitriol, calcityonin and PTH what other hormones affect Ca homeostasis

Answer 23

glucocorticoids
thyroid H
GH
EST and And

Question 24

given Ca conc. is 10 mg/ dl

and pi is 4 mg/dl what are the %distributions of various forms

Answer 24

Ca: 50% ionized- 45% protein bound and 5% complexed with ions

Pi: 84% ionized (Free), 10% protein bound and 6% complexed with ions

Question 25

Vit D

Answer 25

1,25 (OH)2D3- PTH inhibitor

PTH inhibition directly and indirectly

Question 26

Vit D actions

Answer 26

are actions of it:

Essential for acquiring adequate amounts of Ca2+ and Pi from the diet
• Increasesplasma[Ca2+]andplasma[Pi]
•Regulates processes of bone resorption and deposition
(osteoblasts)
• Inhibits PTH secretion

Question 27

alkalemia

Answer 27

dec. ionized Ca

Question 28

A common condition that results:

inc. protein binding of Ca

W/o affecting the total plasma conc. of Ca

Answer 28

Alkalosis

Question 29

Hormones controlling the Ca/Pi homeostasis

Answer 29

PTH, Vit D, Calcitonin

Question 30

VDR

Answer 30

a TF in target tissues:

Small intestine, kidney, bone, PT gland

Question 31

Direct PTH inhibition by Vit D D

Answer 31

by acting on paratyroid gland

Question 32

Slow response of PTH-R expressing cells of the kidney

Which takes hours to days

Answer 32

stimulation of 1,25(OH)2D3 synthesis

Question 33

Acidemia

Answer 33

inc inoized Ca

Question 34

Slow Ca mobilization response of osteoblasts to PTH

Answer 34

via bone remodeling

Question 35

Calcitonin

Answer 35

dec plasma level of both Ca and Pi

Question 36

an increase in plasma concentration decreases PTH secretion via

Answer 36

Ca-sensing receptor mediated mechanisms

Question 37

normal ranges of total plasma level pf Ca and Pi

Answer 37

Ca: 8.8- 10.3 mg/dl ~ 10
Pi: 2.5-4.5 mg/dl ~ 4

Question 38

Nuclear vitamin D receptor

Answer 38

VDR

Question 39

Alkalosis impact on plasma protein-bound Ca and ionized form

Answer 39

protein-bound Inc.

ionized form decreases.