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

Regulation Of Ca And PO4 Metabolism Flashcards

1
Q 
Calcium distribution in the body 
ECF
Plasma
ICF
Bones and teeth
A

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

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2
Q

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

A

Non-ionized form complexed to anions

Ionized form bound to plasma proteins

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3
Q

Ways to alter the concentration of Ca in the plasma

A
  1. Alter total Ca - changes in plasma protein concentration alter total C concentration
  2. Alter anion concentration
  3. Alter Ca fraction bound to proteins
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4
Q

What plasma protein binds Ca in the serum

A

Albumin

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5
Q

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

A

Albumin will bind H+ so more Ca is ionized

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6
Q

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

A

Preferentially binds Ca so will decrease the concentration of ionized Ca

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7
Q

______calcemia increases neuromuscular excitability leading to tetany/spasticity

A

Hypocalcemia

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8
Q

_____calcemia depresses neuromuscular excitability by what mechanism

A

Hypercalcemia shifts the threshold away from membrane potention

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9
Q

Regulators of plasma calcium concentration

A

PTH
Calcitonin
Calcitriol

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10
Q

Causes of low serum calcium

A

Hypoparathyrroidism
Renal disease
Vitamin d deficiency

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11
Q

Organs invovled in the regulation of Ca

A

Bone
Kidney
Intestines

With three hormones
PTH
Calcitriol
Calcitonin

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12
Q

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

A

Inversely correlated to Ca 2+

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13
Q

Regulators of phosphate metabolism

A

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

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14
Q

FGF23 is derived from

A

Bone

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15
Q

Factors that regulate fgf23

A

Phosphate and VitD

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16
Q

Effects of FGF-23

A

Directly downregulates NaPi transporters in kidney

Stimulates PTH to downregulate NaPi transporters in kidney

Decreases calcitriol production in the kidney

17
Q

FGF23 is secreted from the bone in response to

A

PTH
Calcitriol
Hyperphosphatemia

18
Q

FGF23 has what effect on Pi

A

Increases Pi excretion

Slows down resorption

19
Q

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

A

Parathyroid hormone

Secreted from chief cells of parathyroid glands

20
Q

PTH secretion is stimulated by what factors

A

Low plasma (ionized) [Ca2+]

21
Q

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

A

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
Q

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

A

Vitamin D inhibits both these factors

23
Q

Chronic hypercalcemia has what effect on synthesis/storage of PTH

A

Decreases synthesis/storage of PTH

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

24
Q

Chronic hypocalcemia has what effect on synthesis/storage of PTH

A

Increases synthesis/storage

Results in hyperplasia of parathyroid glands

25
Q

In severe hypomagnesia, what occurs to PTH

A

Inhibits PTH synthesis, storage, secretion

26
Q

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

A

GPCR

A cAMP cascade

An IP3/Ca2_ cascade

27
Q

Low plasma [Ca] increases secretion of what hormone

A

PTH

28
Q

Effects of PTH on bone, kidney, intestine

A

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
Q

Functions of vitamin D

A

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
Q

Order of organs for vitD synthesis

A

Skin
Liver
Kidney

31
Q

Liver enzyme of vitD synthesis

A

25-hydroxylase

32
Q

Kidney enzyme of vitD sytnthesis

A

1alpha-hydroxylase
CYP1a

Forms active form of vitD

33
Q

1alpha hydroxylase is stimulated by what factors

A

Decreased [Ca]
Increased PTH
Decreased PO4

Endo/Repro Midterm (6 decks)

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