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Endocrinology > Exam 3: Calcium/phosphate > Flashcards

Exam 3: Calcium/phosphate Flashcards

1
Q

Total Ca2+ concentration in blood

A

10 mg/dl

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2
Q

40% of total blood calcium is bound to ____ and 60% is ____

A

Plasma proteins; unbound

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3
Q

Of the unbound calcium 10% is complexed to which anions

A

Phosphate
Sulfate
Citrate

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4
Q

Of the unbound calcium 50% is

A

Ionized Ca2+

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5
Q

What is the only form of calcium that is biologically active

A

Ionized Ca2+

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6
Q

Hypocalcemia has what effects on body

A 
Hyper-reflexia
Spont. Twitching
Muscle cramps
Tingling
Numbness
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7
Q

Hypocalcemia lowers the threshold potential of

A

Muscle and nerves

Easier to excite

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8
Q

Chvostek sign = twitching of facial muscles elicited by

A

Tapping on CN7

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9
Q

Trousseau sign is a carpopedal spasm after

A

Inflation of sphygmomanometer (BP cuff)

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10
Q

Hypercalcemia neurologic signs

A

Hyporeflexia
Lethargy
Coma — death

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11
Q

Hypercalcemia can also lead to

A

Constipation
Polyurea
Polydipsia

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12
Q

Increase in concentration is associated with

A

Inc in total Ca2+

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13
Q

Changes in anion concentration is ____ proportional to changes in ionized Ca2+

A

Indirectly

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14
Q

Acidemia ultimately causes _____ in ionized Ca2+

A

Inc

Bc more H+ binds to albumin, displaces Ca2+

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15
Q

Alkalemia ultimately causes ____ in ionized Ca2+

A

Dec

Bc less H+ binds to albumin

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16
Q

Calcium homeostasis involves 3 organ systems

A

Bone
Kidney
Intestine

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17
Q

Overall calcium homeostasis involves 3 hormones

A

PTH
Calcitonin
Vitamin D

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18
Q

Role of PTH

A

Regulate Ca2+ ECF concentration

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19
Q

Dec plasma Ca2+ causes ____ PTH from parathyroid glands

A

Inc secretion

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20
Q

____ cells synthesize and secrete PTH

A

Chief

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21
Q

Secretion of PTH is regulated by

A

Plasma Ca2+ concentration

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22
Q

PTH is secreted when plasma Ca2+ concentration goes below _____

A

10 mg/dl

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23
Q

Maximal secretion of PTH occurs at

A

7.5 mg/dl

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24
Q

Chronic hypocalcemia leads to

A

Secondary hyperparathyroidism

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25
Chronis hypercalcemia leads to
Dec synthesis/storage of PTH | Inc breakdown of stored PTH
26
Magnesium effect on PTH
Similar to Ca2+
27
Hypomagnesia
Stims PTH secretion
28
Severe hypomagnesia is associated w/
Alcoholism Inhibits PTH synthesis, storage and secretion
29
Hypermagnesia
Inhibits PTH secretion
30
At the renal proximal tubule PTH inhibits _____ and results in
Renal phosphate reabsorption; phosphaturia
31
At the distal convoluted tubule PTH stimulates
Ca2+ reabsorption
32
PTH has ____ effect on kidney mediated by cAMP
Direct
33
PTH has ____ effect on intestine via activation of Vit D
Indirect Inc calcium absorption via Vit D
34
PTH in bone: receptors located only on
Osteoblasts
35
PTH initially and briefly ____ bone formation
Inc
36
PTH causes an ___ in bone resorption
Inc
37
Net effect of PTH over long haul in bone is
Bone resorption Causes inc in Ca2+ and phosphate to ECF
38
PTH stimulates renal 1a-hydroxylase which converts
25-hydroxycholecalciferol — 1,25 dihydroxycholecalciferol
39
1,25 dihydroxycholecalciferol AKA
Active form of vitamin D
40
Active vitamin D stimulates
Intestinal Ca2+ absorption
41
Primary hyperparathyroidism MC caused by
Parathyroid adenoma
42
Primary hyperparathyroidism causes glands to secrete lots of PTH which causes
Hypercalcemia | Hypophosphatemia
43
Primary hyperparathyroidism causes excretion of excessive amounts of
Ca2+ CAMP Phosphate All can form kidney stones
44
Kidney stones are formed as a result of Ca2+ precipitating as
Ca2+ phosphate Ca2+ oxalate Primary hyperparathyroidism
45
Secondary hyperparathyroidism
Parathyroid normal | Stim to secrete PTH secondary to hypocalcemia
46
Hypocalcemia in secondary hyperpara due to
Vit D deficiency | Chronic renal failure
47
Other aspects of secondary hyperparathyroidism
High PTH | Low/normal plasma Ca2+
48
How to differentiate primary and secondary hyperparathyroidism
Plasma Ca2+ low/normal (secondary) Plasma Ca2+ high (primary)
49
Hypoparathyroidism is a common consequence of
Thyroid surgery
50
Hypoparathyroidism causes
Low PTH Hypocalcemia Hyperphosphatemia
51
Pseudohypoparathyroidism
Gs receptor protein for PTH in kidney/bone is defective Doesn’t activate adenylyl cyclase
52
Pseudohypoparathyroidism AKA
Albright’s hereditary osteodystrophy
53
Pseudohypoparathyroidism causes
Hypocalcemia | Hyperphosphatemia
54
Pseudohypoparathyroidism physical characteristics
Short stature/neck Obesity Subcutaneous calcification Shortened 4th metacarpals/tarsals
55
Humoral hypercalcemia of malignancy
Malignant tumors secrete peptide that is similar to PTH
56
Humoral hypercalcemia of malignancy causes
Hypercalcemia | Hypophosphatemia
57
Humoral hypercalcemia of malignancy has similar findings to primary hyperpara except
Low PTH Suppressed by hypercalcemia
58
Humoral hypercalcemia of malignancy is treated w/
Furosemide — inhibits renal Ca2+ reabsorption Etidronate — inhibits bone resorption
59
Familial hypocalciuric hypercalcemia characterized by
Dec urinary Ca2+ excretion Inc plasma Ca2+
60
FHH caused by mutation of Ca2+ receptors in
Parathyroid glands | Kidney
61
FHH has ___ PTH levels
high (not inhibited as it should be)
62
Calcitonin is synthesized by
Parafollicular cell of thyroid
63
Calcitonin is stored in
Secretory granules
64
What stimulates calcitonin secretion
Inc plasma Ca2+
65
Calcitonin inhibits ____ which leads to ___ plasma Ca2+
Osteoclast bone resorption; Dec
66
Vitamin D promotes
Mineralization of new bone
67
Vitamin D increases plasma levels of
Ca2+ and phosphate
68
Vitamin D is a ___ hormone
Steroid
69
Major site of action of vitamin D
Intestine
70
In intestine vitamin D inc _____ absorption
Ca2+ and phosphate
71
Vitamin D induces synthesis of
Calbindin D-28 K
72
Calbindin D-28 K
Protein that binds 4 Ca2+ May act as shuttle or help to maintain gradient
73
Vitamin D actions in kidney
Inc Ca2+ and phosphate
74
Vitamin D in bone, acts synergistically w/ ___ to stimulate ____
PTH; osteoclast activity and bone resorption
75
Vitamin D deficiency in children
Rickets
76
Rickets: insufficient amounts of ____ which causes ____
Ca2+ and phosphate Growth failure/skeletal deformities
77
Vitamin D deficiency in adults
Osteomalacia
78
Osteomalacia characterized by
New bones failing to mineralize — softening of bones
79
Deficiency of vitamin D effect on other organs
``` CV disease Cancer Infection MS Childhood asthma ```
80
Other functions of vitamin D
``` Controls genes Dec cell proliferation Immunomodulator Controls inflamm Muscle strength BP ```
81
Vitamin D deficiency effect on muscles
Muscle weakness
82
Vitamin D effect on BP
Inhibits renin secretion
83
Vitamin D effect on inflamm
Lack of Vit D = inc CRP and IL-10
84
In response to TB/LPS Vitamin D genes are upregulated which causes inc production of
Cathelicidin — powerful antimicrobial
85
Chronic renal failure characterized by dec production of
Active Vit D
86
Chronic renal failure has ___ PTH levels and ___ bone resorption of Ca2+
High; inc
87
Chronic renal failure causes
Osteomalacia
88
Chronic renal failure exhibits ___ urine phosphate which ___ plasma phosphate
Dec; inc
89
Chronic renal failure ___ plasma Ca2+
Dec

Endocrinology (11 decks)

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