Brainscape's Knowledge GenomeTM

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


See full index

Diabetes and Endocrine - Physiology > Calcium Homeostasis > Flashcards

Calcium Homeostasis Flashcards

1
Q

how is the blood clotting ability of calcium utilised clinically

A

anti calcium agents are used to line the sample tube to prevent blood samples from clotting

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

where is 99% of the body’s calcium

A

in bone as hydroxyapatite

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

what percentage of calcium in the body is free and physiologically active

A

0.05%

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

purpose of calcium in cell signalling

A

their entry and exit into the cell triggers release of hormones (as in B cells for insulin) or neurotransmitters

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

5 roles of calcium

A
  1. signalling
  2. blood clotting
  3. apoptosis
  4. skeletal strength
  5. membrane excitability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how does calcium produce membrane excitation

A

RCMP is produced by Na+/K+ movement. Calcium decreases Na+ permeability and reduces excitability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which of the mentioned 5 roles of calcium is most critical to maintain homeostasis of an why

A

membrane excitability: if nerves/cells become hyperactive or underactive then chaos

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

what state of calcium (hyper/hypo) will cause Na+ permeability in neurons to increase (i.e. hyperexcitation) and what is the clinical consequence

A

HYPOcalcaemia. results in tetany. If this tetany spreads to the chest wall muscles and larynx it can results in asphyxiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

cardiac arrhythmia can be triggered by what state of calcium (hyper/hypo)

A

HYPERcalcaemia. decreased neuronal Na+ permeability –> reduced excitability –> depressed neuromuscular activity

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

what % of body calcium is stored intracellularly for things like muscle contraction

A

0.9%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

normal calcium range in plasma (i.e. ECF)

A

2.2-2.6mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is the 0.1% calcium in plasma distributed

A

10% complexed to anion, 40% protein bound, 50% free

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how does alkalosis increase the amount of calcium bound to proteins

A

fewer H+ ions –> fewer H+ to bind to proteins –> more spaces on proteins to bind to –> Ca2+ binds to spaces on protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

which situation has more protein bound calcium, alkalosis or acidosis

A

alkalosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

true/false calcium in bone will be released if Ca2+ levels in plasma are not sufficient

A

true - osteoclasts secrete H+ to dissolve the hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what cells build up bone

A

osteoBlasts. they lay down a collagen matrix which is then calcified. It is this matrix that calcium is taken from

17
Q

the two key hormones of raising calcium content in blood

A

parathyroid hormone and calcitrol

18
Q

what vitamin is calcitrol derived from

A

vitamin D3

19
Q

3 main sites of PTH action

A

bones, renal tubules and kidneys themselves

20
Q

Ca2+ raising action of PTH on bone

A

stimulating osteoclasts
inhibiting osteoblasts
i.e. more breakdown, less deposition

21
Q

action of PTH to raise Ca2+ in kidneys

A

increase renal excretion of phosphate, so it can’t join back up with calcium to form hydroxyapatite.

stimulate kidneys to make calcitriol from vit D

22
Q

how does PTH raise Ca2+ by acting on the renal tubules

A

by increasing reabsorption of Ca2+ i.e. not be peed out

23
Q

calcitriol formation is stimulated by what hormone in lactating women

A

prolactin

24
Q

how does calcitriol increase gut Ca2+ absorption

A

by increasing expression for calcium transporters in gut

25
Q

2 stimuli of calcitriol formation

A

prolactin and PTH

26
Q

where do we acquire vitamin D from

A

from diet and from cholesterol precursors activated by UV light

27
Q

vitamin D is fat/water soluble?

A

fat soluble

28
Q

what hormones decreases plasma Ca2+

A

calcitonin

29
Q

3 calcium raising action of calcitriol

A
  1. increased absorption in gut
  2. renal absorption
  3. stimulating osteoclasts
30
Q

why might prolactin increase Ca2+

A

because lactating women have an increased demand for calcium as they are producing milk

31
Q

effect of reduced vitamin D on bones

A

less calcitriol produced –> less Ca2+ from gut and kidneys –> PTH works harder –> more phosphate excreted –> greater Ca2+ loss from bone –> weaker, softer bones –> rickets/osteomalacia

32
Q

where is calcitonin secreted from

A

the thyroid gland

33
Q

what stimulates calcitonin release

A

raised blood calcium

34
Q

2 calcium lowering actions of calcitonin

A
  1. inhibit osteoclasts

2. increase renal excretion of Ca2+

35
Q

true/false excess calcitonin causes hypocalcaemia

A

false - its effects are overridden by PTH being stimulated by the low calcium levels produced

36
Q

what hormone might be useful to treat Paget’s disease (overactive osteoclasts)

A

calcitonin –> it inhibits osteoclasts

Diabetes and Endocrine - Physiology (10 decks)

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