Regulation Of Ca And PO4 Metabolism Flashcards Preview

Endo/Repro Midterm > Regulation Of Ca And PO4 Metabolism > Flashcards

Flashcards in Regulation Of Ca And PO4 Metabolism Deck (33)
Loading flashcards...
1

Calcium distribution in the body
ECF
Plasma
ICF
Bones and teeth

.1% ECF
.5% plasma
1% ICF
99% bones and teeth

2

In the plasma, Ca exists in _____ form complexed to anions or ____ form bound to plasma proteins

Non-ionized form complexed to anions

Ionized form bound to plasma proteins

3

Ways to alter the concentration of Ca in the plasma

1. Alter total Ca - changes in plasma protein concentration alter total C concentration
2. Alter anion concentration
3. Alter Ca fraction bound to proteins

4

What plasma protein binds Ca in the serum

Albumin

5

In acedimia, albumin preferentially binds _____, thereby increasing ionized _____ in the serum

Albumin will bind H+ so more Ca is ionized

6

In alkalemia, albumin prefferentially binds _____, thereby decreasing the concentration of ionized _____ in the serum

Preferentially binds Ca so will decrease the concentration of ionized Ca

7

______calcemia increases neuromuscular excitability leading to tetany/spasticity

Hypocalcemia

8

_____calcemia depresses neuromuscular excitability by what mechanism

Hypercalcemia shifts the threshold away from membrane potention

9

Regulators of plasma calcium concentration

PTH
Calcitonin
Calcitriol

10

Causes of low serum calcium

Hypoparathyrroidism
Renal disease
Vitamin d deficiency

11

Organs invovled in the regulation of Ca

Bone
Kidney
Intestines

With three hormones
PTH
Calcitriol
Calcitonin

12

Extracellular concentration is _______ correlated to that of Ca
EC concentration of Pi is regulated by the same hormones as Ca

Inversely correlated to Ca 2+

13

Regulators of phosphate metabolism

Diet
Calcitriol increases plasma
PTH increases plasma []
Renal tubular resorption

14

FGF23 is derived from

Bone

15

Factors that regulate fgf23

Phosphate and VitD

16

Effects of FGF-23

Directly downregulates NaPi transporters in kidney

Stimulates PTH to downregulate NaPi transporters in kidney

Decreases calcitriol production in the kidney

17

FGF23 is secreted from the bone in response to

PTH
Calcitriol
Hyperphosphatemia

18

FGF23 has what effect on Pi

Increases Pi excretion

Slows down resorption

19

Potent regulator of Pi and Ca homeostasis synthesized and secreted from chief cells of what gland

Parathyroid hormone
Secreted from chief cells of parathyroid glands

20

PTH secretion is stimulated by what factors

Low plasma (ionized) [Ca2+]

21

How can the [Ca2+] in the plasma be sensed?

CaSR
Calcium sensing receptor

If a low [Ca] is senses, PTH secretion is induced by the receptor through Gq protein signaling

If high [Ca] os sensed, PTH secretion is inhibited by Gi protein

22

Vitamin D has what effect on the expression of PTH and CaSR

Vitamin D inhibits both these factors

23

Chronic hypercalcemia has what effect on synthesis/storage of PTH

Decreases synthesis/storage of PTH

Breaks down any stored PTH, releases inactive PTH fragments into circulation

24

Chronic hypocalcemia has what effect on synthesis/storage of PTH

Increases synthesis/storage
Results in hyperplasia of parathyroid glands

25

In severe hypomagnesia, what occurs to PTH

Inhibits PTH synthesis, storage, secretion

26

PTH receptor is what type of receptor, using what signaling cascade

GPCR

A cAMP cascade

An IP3/Ca2_ cascade

27

Low plasma [Ca] increases secretion of what hormone

PTH

28

Effects of PTH on bone, kidney, intestine

PTH increases bone resorption
Increases Ca and Pi in blood

Kidney - decreased Pi reabsorption, increased Ca reabsorption, increased urinary cAMP

Intestine - increased Ca absorption (PTH stimulated kidney cells to make and release calcitriol, which acts on intestine)

All increase plasma [Ca] to normal

29

Functions of vitamin D

Promotes mineralization of new bone by increasing Ca and PO plasma concentrations

Has opposing effects on Pi levels va action on kidney and intestine

Increases Ca and Po44 products to promote mineralization of new bone

30

Order of organs for vitD synthesis

Skin
Liver
Kidney

31

Liver enzyme of vitD synthesis

25-hydroxylase

32

Kidney enzyme of vitD sytnthesis

1alpha-hydroxylase
CYP1a

Forms active form of vitD

33

1alpha hydroxylase is stimulated by what factors

Decreased [Ca]
Increased PTH
Decreased PO4