Regulation Of Ca/Pi/Mg & DSA

Question 1

What is the total plasma level of calcium

Answer 1

5 mEq/L

Question 2

What is the biologically active form of Vit. D

Answer 2

Calcitrol

Question 3

Calcitrol acts with PTH to do what

Answer 3

REBS Bone (stimulate osteoclasts)

This increases Ca and Pi plasma concentrations

Question 4

What does Calcitrol do

Answer 4

Increases serum Ca and Pi

Question 5

What does Calcitrol do in the intestine

Answer 5

Increases Ca absorption and Pi absorption

Question 6

What does Calcitrol do in the kidney

Answer 6

Increases phosphate and Ca REBS

Question 7

How does Calcitrol act

Answer 7

Through the VDR to increase serum C and Pi

Question 8

What does calcitonin do to bone

Answer 8

Lowers serum calcium and Pi levels by inhibiting bone REBS and decreasing osteoclasts

Question 9

What does calcitonin do to the kidney

Answer 9

Promotes renal excretion of Ca and Pi

Question 10

Clacitonin opposes what

Answer 10

PTH

Question 11

What is calcitonin stimulated by

Answer 11

Hypercalemia

Question 12

What does PTH do overall

Answer 12

Increases serum Ca and decreases serum Pi

Question 13

What does PTH do in the bone

Answer 13

Increases osteoclastic REBS

Question 14

What does PTH do in the intestine

Answer 14

Increases Ca/Pi absorption via calcitrol production

Question 15

What does PTH do in the kidney

Answer 15

Promotes REBS of Ca in the DCT

Decreases REBS of Pi in the PCT

Decreases the Na/H antiporter - leading to decreased Pi

Stops HCO3 REBS

Question 16

Excessive PTH can lead to what

Answer 16

Hypercalcemia
Low Pi.
Metabolic acidosis

Question 17

What is the role of the CaSR

Answer 17

Monitors Ca levels in the ThALoH

Inhibits Ca REBS when Plasma Ca levels are high

Blocks the NKCC2 which stops paracellular REBS of Ca.

It also blocks the excretion of recycled K, which can lead to relative hyperkalemia

Question 18

Most of the Ca is REBS where

Answer 18

In the PCT

Question 19

How is the Ca REBS in the ThALoH

Answer 19

Lumen positve voltage drives paracellular REBS

Question 20

Where is the major site or regulation of Ca and how

Answer 20

DCT

TRPV5 which is regulated by Vit. D allows Ca to be REBS

Question 21

Volume contraction does what to Ca

What about volume expansion

Answer 21

Increases Ca REBS

Decreases Ca REBS

Question 22

How does the ThALoH REBS Ca

Answer 22

Paracellularly, which follows Na flow

So increased Na REBS means increased Ca REBS, and this is stimulated by ADH

Question 23

How is Ca REBS in the DCT

Answer 23

Via TRPV5 and then into IF via NCE

DCT also has a lumen negative transepithelial voltage which helps pull Ca into the cell

Question 24

Acidemia does what to Ca

What about Alkalemia

Answer 24

Acid - increases Ca excretion by inhibiting TRPV5 (inhibits REBS)

Alkalosis - decreases Ca excretion by stimulating TRPV5 (activates more REBS of Ca through TRPV5)

Question 25

Pi REBS is driven by what

Answer 25

Na/K pump

Question 26

Pi is REBS primarily with what

Answer 26

HCO3

Question 27

What does FGF - 23 do

Answer 27

Secreted by bone in response to PTH, calcitriol, and high Pi Blocks Na/HPO3 symporter thus allowing for increased Pi excretion and decreased Pi REBS

Question 28

What is the most important hormone that regulates Pi excretion

Answer 28

PTH - inhibits the Na/Pi transporter in the PCT This inhibition allows for an excretion of Pi and also cAMP in the urine

Question 29

Chronic acidosis does what to Pi excretion What about chronic alkalosis

Answer 29

Acidosis - increases Pi excretion, lowers plasma Pi Alkalosis - decreases Pi excretion, increases plasma Pi

Question 30

Most Mg is REBS where and how

Answer 30

In the ThALoH paracellularly, dependent on the NKCC to make a negative charge for it to be attracted to

Question 31

How does Mg cross the apical membrane of the DCT

Answer 31

TRPM6

Question 32

What is the serum K level

Answer 32

3.5 - 5.0

Question 33

What is defined as hyperkalemia and what causes it

Answer 33

K>5.2 Causes by rhabdo, burns, hemolysis, ICF to ECF shifts

Question 34

Most K is stored where

Answer 34

In the muscle

Question 35

What does hyperkalemia cause in the heart

Answer 35

Hyperpolarized membrane Elongated QRS Peaked T waves Vfib

Question 36

What does hypokalemia casue in the heart

Answer 36

Hypopolarizes the membrane Allows for bradycardias, pac’s, pvc’s

Question 37

What are some causes of of hypercalcemia

Answer 37

Increased PTH Polyuria Increased calcitrol Sarcardosis

Question 38

What care some causes of hypocalcemia

Answer 38

Decreased PTH Decreased Calcitrol Increased or decreased Mg

Question 39

What are some causes of hypokalemia

Answer 39

Increased insulin Alkalosis Decreased Mg

Question 40

What primarily causes hyperkalemia

Answer 40

Kidney failure

Question 41

What causes hyperphosphate

Answer 41

Decreased PTH Rhabdo Laxatives

Question 42

What are some causes of hypophosphate

Answer 42

Increased PTH DKA Fanconi syndrome

Question 43

Increased Mg means what as far as PTH and Ca

Answer 43

Decreased PTH and decreased Ca

Question 44

Low K means what as far as cardiac repol What about High K

Answer 44

Low - prolonged repol High - enhanced repol

Question 45

What is adequate Ca intake for adults

Answer 45

1000 mg/day

Question 46

What peptide does calcitonin act through

Answer 46

Calcitonin gene-related peptide (CGPR)