2-4-16-Regulation Of Ca And PO4 Metabolism (Lopez) Flashcards Preview

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Flashcards in 2-4-16-Regulation Of Ca And PO4 Metabolism (Lopez) Deck (62):
1

___ is twitching of the facial muscles elicited by tapping on facial n.

Chvostek sign

2

___ is carpopedal spasm upon inflation of a BP cuff

Trousseau sign

3

__ is characterized by a decreased QT interval, constipation, lack of appetite, polyuria, polydipsia, muscle weakness, hyporeflexia, lethargy, and coma

Hypercalcemia

4

___ reduces the activation threshold for Na channels --> easier to evoke an AP (less or no stimulus required to trigger an AP). THis results in increased membrane excitability and can produce numbness and tingling and muscle twitches

Hypocalcemia --> generation of spontaneous AP is the physical basis for hypocalcemic tetany

5

___ is characterized by decreased membrane excitability and the NS becomes depressed and reflex responses are slowed

Hypercalcemia

6

During ___, free ionized [Ca] increases because less Ca is bound to albumin

Acidemia --> leads to increased free ionized [Ca]; H+ kicks off the Ca2+ from albumin

7

During ___, free ionized [Ca] decreases, often accompanied by hypocalcemia

Alkalemia --> decreased ionized [Ca]; Ca stays on albumin since H+ does not displace it

8

Ca homeostasis is tightly regulated by these 3 organs ___ and these 3 hormones ___

Bones, kidneys, and intestine

PTH, calcitonin, Vit D

9

___ is an intracellular anion involved in the activation and deactivation of enzymes, as well as a buffer in bone, serum, and urine

PO4--> bone (85%), Plasma (

10

EC [Pi] is __ related to that of [Ca]

Inversely

11

The __ cells of the parathyroid glands synthesize and secrete PTH

Chief

12

What is the main stimulus for secretion of PTH?

Decreased plasma [Ca]

13

___ is characterized by long-term increased levels of plasma [Ca] and causes decreased synthesis and storage of PTH, increased breakdown of stored PTH and release of inactive PTH fragments into circulation

Chronic hypercalcemia

14

___ is characterized by long-term decreased plasma [Ca] and causes increased synthesis and storage of PTH, and hyperplasia of parathyroid glands (secondary hyperparathyroidism)

Chronic hypocalcemia

15

Severe hypomagnesemia can cause what?

Inhibition of PTH synthesis, storage, and secretion --> result of chronic Mg2+ depletion, as in alcoholism

16

PTH acts via this secondary messenger system___

Adenylate cyclase/cAMP

17

List the physiological affects of PTH on:

A-bone
B-Kidney
C-Intestine

A-Increased bone resorption
B-Decreased Pi reabsorption (phosphaturia), increased Ca reabsorption, increased urinary cAMP
C-Increased Ca reabsorption (via Vit D)

All will increase plasma [Ca] toward normal

18

__ promotes mineralization of new bone through its coordinated actions in the regulation of both Ca and Pi plasma concentrations

Vitamin D --> "steroid" hormone

19

In vitamin D synthesis, 7-dehydrocholesterol is converted to cholecalciferol via UV light. Cholecalciferol is then converted to 25-OH-cholecalciferol in the liver by this enzyme ___

25-hydroxylase

20

25-OH-cholecalciferol is converted to 1,25-(OH)2-cholecalciferol in the renal PCT by this enzyme ___

1-alpha-hydroxylase (CYP1alpha)

21

PTH receptors are located on these cells ___

Osteoblasts (not osteoclasts)

22

What are the short-term actions of PTH on bone?

What are the long-term actions of PTH on bone?

Short-term: Bone formation (via direct action on osteoblast) --> basis for use of intermittent synthetic PTH administration in osteoporosis treatment

Long-term: Increase bone resorption (indirect action on osteoclasts mediated by cytokines released from osteoblast)

23

___ acts synergistically with PTH to stimulate osteoclast activity and bone resorption

Vitamin D

24

In the formation and resorption in bone, ___ induces stem cells to differentiate into osteoclast precursors, mononuclear osteoclasts, and finally as mature multinucleated osteoclasts

M-CSF

25

___ is a cell surface protein produced by osteoblasts, bone lining cells, and apoptotic osteocytes. It is the primary mediator of osteoclast formation

RANKL (Receptor activator for NF-kB ligand)

26

___ is a cell surface protein receptor on osteoclasts and osteoclast precursors

RANK

27

___ is a soluble protein produced by osteoblasts, a decoy receptor for RANKL, inhibitor of RANK/RANKL interaction

Osteoprotegerin

28

Osteoclast formation can occur via this ligand-receptor interaction ____

RANKL-RANK

Osteoprotegerin inhibits

29

___ increases RANKL and decreased osteoprotegerin

___ increases RANKL

PTH

Vit D

30

List the MOA of PTH on the kidney, specifically cells of the PCT

PTH binds its receptor on the basolateral membrane --> stimulates a Gs-Adenylate cyclase-cAMP 2nd messenger system --> activates protein kinase -->Phosphorylation--> inhibits Na-PO4 co-transporter to reabsorb both from the lumen (apical membrane)

31

Inhibition of the Na-PO4 co-transporter on the apical membrane (lumen side) of the cells of the PCT causes ___

Phosphatria (increased excretion of Pi in urine)

32

What are the actions of Vit D on the kidney?

Stimulates both Ca and Pi reabsorption

33

In the SI, vitamin D increases Ca and Pi absorption by increasing ___ expression

Calbindin

34

In the parathyroid gland, Vitamin D directly inhibits ___ expression and directly stimulates ___ expression

PTH gene

CaSR gene

35

___ decreases blood Ca and Pi concentrations by inhibiting bone resorption. It decreases the activity and number of osteoclasts

Calcitonin --> major stimulus=increased plasma [Ca]

36

A thyroidectomy will have what effect on calcitonin and Ca metabolism?

A thyroid tumor will have what effect on calcitonin and Ca metabolism?

Thyroidectomy --> decreased calcitonin, no effect on Ca metabolsim

Thyroid tumor --> increased calcitonin, no effect on Ca metabolism

37

____ stimulates intestinal Ca absorption and renal tubular Ca reabsorption. It is also one of the most potent regulators of osteoblast and osteoclast function (promotes survival of osteoblasts and apoptosis of osteoclasts which favors bone formation)

Estradiol-17b

38

___ promote bone resorption and renal Ca wasting and inhibit intestinal Ca absorption

Adrenal glucocorticoids (cortisol)

39

In this disorder, pts excrete excessive amounts of Pi, cAMP, and Ca (Ca-oxalate stones).

Primary hyperparathyroidism --> "stone" "bones" and "groans" ; hypercalciuria (stones), increased bone resorption (bones), constipation (groans)

40

What is a possible tx for primary hyperparathyroidism?

Parathyroidectomy

41

List levels of PTH, Ca, Pi, and Vit D in primary hyperparathyroidism:

PTH=increased
Ca=Increased
Pi=Decreased
Vit D=Increased

42

___ is characterized by increased PTH levels secondary to low [Ca] in blood. The low [Ca] can be caused by renal failure and vit D deficiency

Secondary hyperparathyroidism

43

List levels of PTH, Ca, Pi, and Vit D in secondary hyperparathyroidism due to Renal failure

PTH=increased
Ca=decreased
Pi=Increased
Vit D=decreased

44

List levels of PTH, Ca, Pi, and Vit D in secondary hyperparathyroidism due to Vit D deficiency

PTH=Increased
Ca, Pi, Vit D=all decreased

45

___ can be caused by thyroid and/or parathyroid surgery or can be autoimmune. Most symptoms are associated with decreased Ca which can lead to muscle spasm or cramping, seizures, numbness, tingling, or burning

Hypoparathyroidism --> tx with oral Ca supplement and active form of Vit D

46

List levels of PTH, Ca, Pi, and Vit D in Hypoparathyroidism

PTH=decreased
Ca=Decreased
Pi=Increased
Vit D=decreased

47

__ is an inherited autosomal dominant disorder with a defect in Gs protein for both PTH in bone and the kidneys are defective. This leads to development of hypocalcemia and hyperphosphatemia. Phenotype includes short stature, short neck, obesity

Albright hereditary osteodystrophy (pseudohypoparathyroidism type 1a)

48

List levels of PTH, Ca, Pi, and vit D for Albright hereditary Osteodystrophy (pseudohypoparathyroidism type 1a)

PTH=increased
Ca=Decreased
Pi=increased
Vit D=decreased

49

What are some symptoms of hyperparathyroidism?

Kidney stones
Osteoporosis
GI disturbances
Muscle weakness,
Depression
Polyuria
High serum [Ca], low serum [PO4]

50

What are some symptoms of hypoparathyroidism?

Tetany, convulsions, parasthesias, muscle cramps
Decreased myocardial contractility
1st degree heart block
CNS problems-irritability and psychosis
Intestinal malabsorption
Low serum [Ca]; high serum [PO4]

51

___ is a disorder characterized by increased PTHrP levels and produces a similar profile to primary hyperparathyroidism such as increased urinary Ca, increased urinary Pi, cAmp as well as increased blood Ca and decreased blood Pi

Humoral hypercalcemia of malignancy

52

___ is a peptide produced by tumors with close homology in the N-terminal to PTH

PTHrP --> binds and activates same receptor as PTH

53

What is a tx for humoral hypercalcemia of malignancy?

Furosemide --> inhibits renal Ca reabsorption and increases Ca excretion

Etidronate --> inhibitor bone resorption

54

List levels of PTH, Ca, Pi, and Vit D for humoral hypercalcemia of malignancy

PTH=decreased
Ca=Increased
Pi=decreased
Vit D=decreased

55

__ is an autosomal dominant disorder caused by a mutation that inactivates CaSR in parathyroid glands and parallel Ca receptors in the ascending limb of the kidney. It results in decreased urinary Ca excretion (hypocalciuria) and increased serum [Ca] (hypercalcemia)

Familial Hypocalciuric Hypercalcemia (FHH)

56

List PTH, Serum Ca, Urine Ca, Pi, and Vit levels for FHH

PTH=increased
Serum Ca=increased
Urine Ca=decreased
Pi=N
Vit D=N

57

___ occurs when there is an insufficient amount of Ca and Pi available to mineralize growing bone and characterized by growth failure and skeletal deformities. Most common in children

Rickets

58

__ is when new bones fail to mineralize and characterized by bending and softening of weight-bearing bones

Osteomalacia

59

List the deficit in Pseudovitamin D-deficient Rickets of Vitamin D-dependent rickets Type 1

List the deficity in Pseudovitamin D-deficient Rickets or Vitamin D-dependent Rickets Type 2

Type 1--> decreased 1-alpha-hydroxylase

Type 2--> decreased vitamin D receptor

60

List PTH, Ca, Pi, urine, vit D levels and bone disturbances in the pathophysiology of Vitamin D

PTH=Increased (secondary)
Ca=N/decreased
Pi=decreased
Urine=Increased Pi and increased cAMP
Vit D=decreased (primary disturbance)
Bone=osteomalacia, increased resorption

61

List treatments for osteoporosis

Antiresorptive therapy --> biphosphonates, estrogen, Selective estrogen receptor modulators, calcitonin, RANKL inhibitors (Denosumab)

Anabolic therapy --> PTH

62

__ is characterized by hyperreflexia, spontaneous twitching, muscle cramping, tingling and numbness, as well as + Chvostek sign and + Trousseau sign

Hypocalcemia --> decreased [Ca2+]