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Phg 204 > HORMONES THAT REGULATES CALCIUM HOMEOSTASIS > Flashcards

HORMONES THAT REGULATES CALCIUM HOMEOSTASIS Flashcards

1
Q

Daily net changes in calcium are as follows:

  • About ___mg of Ca 2+ is ingested per day.
  • Only ___ of this is absorbed from the intestine (___mg) and enters ECF.
  • Part of Ca 2+ in ECF is lost through ___ secretion (___mg) back into the gut.
  • ____% of calcium is in skeleton
A

1000

1/3

360

enteric; 190

99

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2
Q

FORMS OF CALCIUM IN THE BLOOD
-The total Ca 2 ± concentration in blood is normally __ mg/ dL

  • Of the total Ca 2 ± , __% is bound to plasma proteins, mainly _____.
  • The ultrafilterable component includes a (small or large?) portion that is complexed to _____ (e.g., phosphate, sulfate, and citrate) and free, ionized Ca Ca 2 ± 2 ± .
A

10

40

albumin

small

anions

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3
Q

The Free, ionized Calcium amounts to ___% of the total (i.e., __ mg/ dL), and it is the only form of Ca2+ that is biologically ____

A

50

5

active.

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4
Q

Forms of calcium in blood
____% bound to protein
____% ultrafiltratable(___-to anions; ____-free)

A

40

60

10

50

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5
Q

Hypocalcemia

Symptoms are:

  • (hyporeflexia or hyperreflexia?)
  • spontaneous ____
  • muscle _____
  • _____ and ____
A

hyperreflexia

twitching

cramps

tingling and numbness

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6
Q

Chvostek sign: ____ of the ____ muscles elicited by tapping on the ____ nerve

Seen in Hyp__calcemia

A

twitching

facial

facial

O

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7
Q

Trousseau sign: which is _____ upon inflation of a ______

Xterics of hyp__calcemia

A

carpopedal spasm

blood pressure cuff

O

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8
Q

Hypercalcemia

-Manifestations of hypercalcemia include

____
poly___

poly____

neurologic signs of ___reflexia

A

constipation

uria

Dipsia

hypo

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9
Q

lethargy and coma

Hypercalcemia or hypocalcemia

A

Hypercalcemia

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10
Q

PARATHYROID HORMONE

-The ____ cells of the parathyroid glands synthesize and secrete PTH, a single chain polypeptide with ___ amino acids.

A

chief

84

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11
Q

PARATHYROID HORMONE

The molecule’s biologic activity resides entirely in the _ terminal __ amino acids.

A

N; 34

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12
Q

When the plasma Ca 2+ concentration ___eases, PTH is secreted by the parathyroid glands.

A

Decr

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13
Q

Mechanism of parathyroid hormone Action

  • PTH binds on receptor on the renal ____ at the _____ membrane
  • The receptor is coupled, via a _____ A
A

proximal tubule

basolateral

adenylyl cyclase

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14
Q

Inhibition of Na +– phosphate phosphate cotransport results in ___eased phosphate reabsorption and ____

A

Decr

phosphaturia

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15
Q

REGULATION OF PTH

Action on bone

  • PTH has several actions on bone, some direct and some indirect.
  • In bone, receptors are located on osteo___ but not on osteo____
A

Blasts

Clasts

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16
Q

REGULATION OF PTH

Action on bone
-after binding to the receptors on osteo___
Initially and briefly, PTH causes an ___ease in bone formation by a direct action on ___. (This brief action is the basis for the usefulness of ____ PTH administration in the treatment of ____

A

Blasts

Incr

osteoblasts

intermittent

osteoporosis

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17
Q

REGULATION OF PTH

Action on bone

In a second, ___ lasting action on osteoclasts, PTH causes an increase in resorption. This second action on osteoclasts is (direct or indirect?) and mediated by _____ released from osteoblasts.

A

long

indirect

cytokines

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18
Q

osteoblasts, are required for the boneresorbing action of PTH on osteoclasts

T/F

A

T

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19
Q

Parathyroid hormone
Action on Kidney
(A)PTH ____ phosphate reabsorption by inhibiting ______ cotransport in the ____

A

inhibits

Na + phosphate

PCT

20
Q

Parathyroid hormone

Action on kidney

PTH ____ Ca 2+ reabsorption.

This second renal action of PTH is on the ___ and complements the increase in plasma Ca 2+ concentration that resulted from the combination of bone resorption and phosphaturia

A

stimulates

DCT

21
Q

Parathyroid hormone

Action on INTESTINE

PTH (directly or indirectly?) act by stimulating renal _____, the enzyme that converts 25hydroxycholecalciferol to the active form of vitamin D 1 , 25 hydroxy chole calciferol

A

indirectly

l α hydroxylase

22
Q

Pathophysiology

(A)Primary hyperparathyroidism

  • commonly caused by _____ (tumors) which secrete excessive amounts of PTH.
  • Persons with primary hyperparathyroidism are said to have “stones’ “bones,” and “groans”
  • stones from _____
  • bones from ____ased bone resorption
  • groans from _____.
  • treatment is by _____ of the parathyroid glands.
A

parathyroid adenomas

hypercalciuria

incr

constipation

surgical removal

23
Q

Secondary hyperparathyroidism
-the parathyroid glands are ____ but are stimulated to secrete _____ PTH secondary to hypocalcemia, which can be caused by ____ deficiency or ____ failure.
In this, PTH levels are (elevated or depressed?) but blood levels of Ca are __ or _____ but never ____.

A

normal

excessive

vitamin D

chronic renal

elevated

low; normal; high

24
Q

Hypoparathyroidism.

  • Commonly occurs because of ____ or ______ , while ______ and ____ hypoparathyroidism are less common.
  • Characterized by low circulating levels of PTH, hypocalcemia, and hyperphosphatemia.
  • Treatment: combination of an _____ supplement and the _____ of _____
A

thyroid surgery or parathyroid surgery

autoimmune and congenital

oral Ca 2+

active form of vitamin D.

25
Q

Pseudohypoparathyroidism

  • First described by ____ in ____.
  • Patients present ___calcemia, ___phosphatemia, and a characteristic phenotype consisting of (short or tall?) stature, (short or tall?) neck, obesity, subcutaneous ______, and (shortened or lengthened?) ___ metatarsals and metacarpals and thus called _______
A

Fuller Albright

1940

Hypo; hyper

short; short

calcification
Shortened

fourth

Albright’s hereditary osteodystrophy.

26
Q

Humoral hypercalcemia of malignancy.

  • Some malignant tumors (e.g., lung, breast) secrete ______ rp ), with similar structure and functions that PTH possesses
  • similar Outcome that is seen in _____
  • However, in humoral hypercalcemia of malignancy, circulating levels of PTH are ___ because PTH secretion by the parathyroid glands, which are normal, is suppressed by the hypercalcemia.

-Treatment:_____ which inhibits renal Ca 2+ reabsorption , and increases Ca 2+ excretion, and inhibitors of bone resorption such as ______.

A

PTH related peptide

primary hyperparathyroidism.

Low

Furosemide

etidronate

27
Q

Calcitonin

  • Calcitonin is a straight chain peptide with ____ amino acids.
  • the major stimulus for calcitonin secretion is ____ased plasma Ca 2+ concentration .
  • The major action of calcitonin is to ____ osteoclastic bone resorption, which decreases the plasma Ca 2+ concentration.
A

32

incre

inhibit; decreases

28
Q

calcitonin participates in the minute to minute regulation of the plasma Ca 2+ concentration in humans.
T/F

A

F

29
Q

Vitamin D

-Comes from 2 main sources: Diet (vitamin D_ or ___calciferol) Skin(vitamin D_ or ____calciferol)

A

2; ergo

3; chole

30
Q

Vitamins D2 and D3

Identical in structure

Have identical functions

T/F

A

F

T

31
Q

(Passive or Active?) transport of Ca 2+ from the intestine is increased by a metabolite of vitamin D
T/F

A

Active

T

32
Q

While PTH role is to maintain the plasma Ca 2+ concentration and increase the ionized Ca 2+ concentration toward normal.
-The role of vitamin D is to promote _____ of ____ , and its actions are coordinated to increase both concentrations in plasma___ and ____ so that these elements can be deposited in new bone mineral.

A

mineralization of new bone

Ca 2+ and phosphate

33
Q

Synthesis of Vitamin D

  • There are two sources of cholecalciferol in the body:
  • From ingested diet or synthesized in the skin from _____ in the presence of ____
A

7dehydrocholesterol

ultraviolet light.

34
Q

Cholecalciferol is physiologically (active or inactive?)

It is ____ in the ____ to form _____ that is (active or inactive?) .

A

inactive

hydroxylated

Liver

25hydroxycholecalciferol

Inactive

35
Q

In the ___, 25hydroxycholecalciferol, is further ___ to produce _____, which is the physiologically (active or inactive ?) form.
-this process is catalyzed by the enzyme _____, which is regulated by several factors, including the plasma Ca concentration and ___.

A

kidney

hydroxylated

1,25 dihydroxycholecalciferol

Active

1a hydroxylase

PTH

36
Q

Actions of Vitamin D

  • In the Intestine: Ca 2+ 1,25dihydroxycholecalciferol ____
  • On the Kidney. The actions of 1,25dihydroxycholecalciferol on the kidney are parallel to its actions on the intestine . it stimulates ______.
  • On the Bone. It acts _____ with ____ to stimulate osteo_____ activity and bone ____.
A

increases calcium and phosphate absorption

both Ca 2+ and phosphate reabsorption

synergistically with PTH

clast

resorption

37
Q

Initial action of active vitamin D3 on bones may seem paradoxical, since the overall action of 1,25dihydroxycholecalciferol is to promote bone mineralization.

However, mineralized “__” bone is ____ to provide more Ca 2+ and phosphate to ___ so that “__” bone can be mineralized (bone ______ ).

A

old; resorbed

ECF

new

remodeling

38
Q

DEFICIENCY of vitamin D
(1) Rickets: a condition in _____ in which ____ amounts of calcium and phosphate are available to mineralize the growing bones. Rickets is characterized by ___ failure and _____ deformities.
This condition is rare in areas of the world where ____ is supplemented and when there is adequate exposure to ____

A

children

insufficient

growth; skeletal

vitamin D

sunlight

39
Q

DEFICIENCY of vitamin D

Osteomalacia : vitamin D deficiency in ____
It’s a condition in which new bone fails to ___, resulting in ____ and ____ of the _____ bones.

A

Adults

mineralize

bending and softening

weight bearing

40
Q

DEFICIENCY of vitamin D

Vitamin D resistance: occurs when the ____ is unable to _______ .

Vitamin D resistance can be caused by the _____ of _____ or, more commonly, by _______ failure.

A

kidney

produce the active metabolite, 1,25 dihydroxycholecalciferol

congenital absence; l αhydroxylase

chronic renal

41
Q

Effects of other hormones on calcium homeostasis

Estrogens
- prevents _____ by a (direct or indirect?) effect on osteoblasts. through _____ of stimulatory effect of certain ____

A

osteoporosis

direct

Inhibition

cytokines

42
Q

Effects of other hormones on calcium homeostasis

Insulin
-____eases the action of bone formation

A

Incr

43
Q

there is little bone loss in untreated Diabetes MELLITUS
T/F

A

F

It’s significant

44
Q

Effects of other hormones on calcium homeostasis

Insulin- like growth factor (IGF1)
- stimulates protein ____ in bone

A

synthesis

45
Q

Effects of other hormones on calcium homeostasis

Growth hormone

  • ___eases Ca 2+ excretion in urine
  • ___eases intestinal absorption

-Effect of GH results in a ____ Ca 2+ balance

A

Incre

Incr

+ ve

46
Q

Effects of other hormones on calcium homeostasis

Glucocorticoids

  • Over long periods it cause _____ by ___eased bone formation and __eased bone reasorption.
  • ____ease bone formation by ____ protein synthesis in osteoblasts
  • ___eases the Absorption of Ca by an anti2+ & PO 4 from intestine Vit D action and ___ renal excretion of these ions.
A

osteoporosis; decr; incr

Decreases

inhibiting

Decreases

increase

Phg 204 (9 decks)

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