Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human phys II, Exam 2 > ca2+ and phosphate > Flashcards

ca2+ and phosphate Flashcards

1
Q

calcium and phosphate levels are regulated by what three main compounds

A
  • parathyroid hormone
  • calcitonin
  • vitamin D
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

where is calcitonin created and secreted from

A

thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

where is parathyroid hormone created and secreted from

A

parathyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does humoral secretion of hormones means

A
  • hormone secretion set by concentration of substance in blood and whether it is above or below the setpoint
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what triggers parathyroid hormone release

A

low plasma Ca2+ triggers hormone release from parathyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

PTH is synthesized in what cells

A
  • chief cells
    • ca2+ receptors are located on chief cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

PTH is synthesized as

A

preproPTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does increases in extracellular CA2+ inhibit PTH secretion

A
  1. ca2+ binds to receptor coupled to G protein -> PLC activated -> IP3 increases Ca2+ which inhibits release of granules containing PTH
  2. increased Ca2+ also inhibits PTH synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where is parathyroid gland located

A

four parathyroid glands lie on the posterior side of the thyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the main effect of PTH

A
  • promote bone resorption releasing both Ca2+ and PO4 into ECF
  • also promotes Ca2+ reabsorption at the kidney
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

PO4 released from bone has what effect on free Ca2+

A
  • PO4 released during bone resorption will bind with Ca2+ in the ECF limiting rise in free Ca2+
  • therefore, PTH inhibits PO4 reabsorption at the kidney to limit the rise in ECF PO4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

PTH actions on the kidney

A
  1. inhibit PO4 reabsorption
  2. stimulates Ca2+ reabsorption
  • net effect: fall in plasma PO4 and rise in plasma free Ca2+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

vit D has affects on what organs

A
  • bone
  • kidney
  • intestine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

vit D actions on intestine

A
  • activated vit D stimulatues Calbindin synthesis, which then increases intestinal absorption of Ca2+ and PO4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

the small intestine absorbs Ca2+ by two mechanisms. which one is not under control of Vit D

A
  • the passive, paracellular absorption of Ca2+ that occurs throughout the small intestine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

the small intestine absorbs Ca2+ by two mechanisms. which one IS under control of Vit D

A
  • active, transcellular absorption of Ca2+ that occurs in the duodenum
  • active form of vit D: D-25-dihydroxyvitamin D stimulates all three of the following steps
    • ca2+ enters cell across apical membrane through a channel
    • inside cell, Ca2+ in buffered by binding proteins and is taken up into intracellular organelles
    • Ca2+ exits cell through a Na-Ca exchanger
17
Q

what enzyme is responsible for making vit D active

A

1-alpha-hydroxylase

18
Q

where can vit D come from

A
  • 7-dehydrocholesterol acted on by UV light -> cholecalciferol
  • cholecalciferol from diet
19
Q

actions of vit D on kidney

A
  • promotes Ca2+ reabsorption from distal tubule
  • negative feedback: inhibits 1-hydroxylase required for activation of vit D
20
Q

actions of vit D on bone

A
  • direct effect: mobilize Ca2+ from bone (bone resorption)
  • indirect effect: promotes bone mineralization by providing more Ca2+
21
Q

PTH has what 3 effects on the kidney

A
  1. protmoes Ca2+ reabsorption and thus an increase in plasma Ca+
  2. inhibits Pi reabsorption
  3. promotes the hydroxylation of 25-hydroxyvitamin D, thereby creating the active metabolite of vit D
22
Q

PTH effect on bone

A

promotes net bone resorption and hence increases plasma Ca2+

23
Q

PTH actions of intestine

A
  • the active form of vit D, produced indurectly as the result of PTH) enhances CA2+ absorption
24
Q

calcitonin is produced by what cells

A

parafollicular cells (C cells) of thyroid gland

25
Q

effects of calcitonin

A
  • ***decrease in plasma Ca2+ levels
  • inhibits bone resorption of ca2+ and phosphate
  • stimulates excretion of Ca2+ and PO4 in urine
26
Q

what is rickets

A

vitamin D deficiency in childhood

  • insufficient ca2+ and PO4 to mineralize growing bone
  • hypocalcemia from decresed Ca2+ and PO4 absorption from gut
  • growth failutre and skeletal anomalies
  • elevated PTH
27
Q

tx of rickets

A

proper diet and vit D supplements

28
Q

what is osteomalacia

A
  • deficiency of vit D in adulthood
  • causes: dietary deficiency, intestinal sx, lack of sunlight, chronic renal failure
  • presentation
    • soft, weak bones, frequent fx
29
Q

tx of osteomalacia

A
  • vit D
  • calcium
  • phosphate supplements
30
Q

what is hypocalcemic tetany

A
  • decreased extracellular ca2+ destabilizes neuronal membranes, lowers threshold
  • peripheral nerves begin to discharge spontaneously
  • skeletal muscles contract tetanically (successive contractions that are fused together)
31
Q

drinking a lot of colas can have what effect on ca2+ concentration

A
  • excess dietary intake of PO4 can lead to decrease in plasma Ca2+
  • PO4 inhibits activation of vit D
  • decreased plasma Ca2+ -> increased PTH secretion
    • leads to phosphaturia
      • ca2+ and PO4 mobilized from bone due to elevated PTH
32
Q

clinical signs of hyperparathyroidism

A
  • “stones, bones, groans”
  • hypercalcemia
  • hypophosphatemia
  • osteoporosis
  • kidney stones
  • muscle weakness
    • decreased muscle excitability
33
Q

clinical presentation of hypoparathyroidism (usually seen post thyroidectomy)

A
  • hypocalcemia
  • hyperphosphatemia
  • tetany
  • convulsions
  • tx: calcium and vit D
34
Q

what is pseudohypoparathyroidism

A
  • G protein receptors on target tissues not functional
  • disturbances
    • elevated PTH
    • hypocalcemia
    • hyperphosphatemia
  • growth abnormalities

Human phys II, Exam 2 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions