Brainscape's Knowledge GenomeTM

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


See full index

Integration finals > calcium regulation > Flashcards

calcium regulation Flashcards

1
Q

Ionised calcium level

A

1.3-1.5mmol/L (4.5-5.6mg/dL)

physiologically active

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

Total plasma calcium level:

A

2.1 – 2.6 mmol/L (9-

11mg/dL)

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

Exists in 2 forms

A

55% Diffusible (ionized ~active & non-ionized ~inactive)

- 45% protein bound

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

Function of calcium in the body

A

extracellular matrix compartmentt, ecf, icf

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

Extracellular matrix

compartment (1)

A

99% total body Ca

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

Extracellular matrix

compartment (2)

A

Formation of

bone & teeth

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

ECF (1)

A

0.1% total body Ca

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

ECF (2)

A

Hormonal excitationsecretin (i.e gastrin)

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

ECF (3)

A 
Cardiac & smooth
muscle contraction
Neuron excitation
Coagulation
cascade
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Icf (1)

A

0.9% total body Ca

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

icf (2)

A

• Skeletal muscle

contraction

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

icf (3)

A

Membrane
excitation by
regulating Ca2+
influx

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

Calcium Homeostasis

A

3 organs and 3 hormones

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

3 organs:

A

 Bone
 Kidney
 Small intestine

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

3 hormones:

A

 PTH
 Vit D (calcitriol)
 Calcitonin

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

Factors Affecting Ca2+ absorption (1) high ca absorption

A 
pH (presence of H+) in intestine
Bile salts
PTH & calcitriol
hormones
Calbindin -carrier protein
in intestine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Factors Affecting Ca2+ absorption (1) low ca absorption

A 
Calcitonin hormone
-Diet (nuts, spinach)
-malabsorption
(celiac disease)
Phosphates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Calcium absorption: pH

A

H+ and Ca2+ compete for binding sites on the albumin molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Metabolic acidosis

A 
↑ available H+
more H+ binds to
albumin
low  Ca2+ binding to
albumin
↑ ionised calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Metabolic alkalosis

A 
low available H+
less H+ binds to
albumin
↑Ca2+ binding to
albumin
lowionised calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Calcium absorption: Ca2+ level

A

Absorption site: Small intestine (90%) (10 site: duodenum), Large intestine (10%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Two distinct mechanisms of absorption:

A

Active transcellular absorption (when calcium intake low*)
Passive paracellular absorption
(when calcium intake is
moderate or high)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Calcium absorption: Calbindin level

1) Transcellular entry

A

Lumen to Passive entry to transport across cell via calbindin to Active
transport exit to Blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

entry of transcellular entry

A

passive entry via Ca2+

channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how transcellular entry is exported out

A

• Active transport Ca2+ -ATPase pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Calcium absorption: Calbindin level

1) paracellular entry

A

Tight junctions:
Vit D regulates tight
junction permeability
for Ca2+ absorption

27
Q

Influence of Ca2+ on neuronal excitability

A

↑ free Ca 2+ to ↓ permeability to Na+ to less
influx of Na+ to resting potential farther
from threshold to ↓ generation of action
potential to ↓ n e r v e excitability

28
Q

Hormonal Regulation of Calcium Level

A

pth, active vt d (calcitriol), calcitonin

29
Q

Hormonal Regulation of Calcium Level : pth

A
  • Increase Ca2+ level by acting on bone, kidney & GIT
  • ↑ bone resorption (Ca2+ release from bone)
  • ↑ conversion of 25-HCC to 1,25-DHCC (active Vit. D)
  • ↓ Ca2+ secreted in milk to conserve Ca2+
30
Q

Regulation of Parathyroid Hormones

A

 Direct Calcium Feedback Loop

 Indirect Calcium Feedback Loop

31
Q

Regulation of Parathyroid Hormones :

 Direct Calcium Feedback Loop

A

↓ Serum Ca2+ → stimulate PTH secretion
→ mobilization of Ca2+ from bone
(resorption)

32
Q

Regulation of Parathyroid Hormones :

 Indirect Calcium Feedback Loop

A

↑ Serum PO4- →stimulate PTH secretion
and influence Ca2+ absorption in intestine
via Calbindin

33
Q

Abnormalities in PTH secretion

A

hyperparathyroidism and hypoparathyroidism

34
Q

Hyperparathyroidism

A 
• Consequences: hypercalcaemia,
hypercalciuria, hypophosphataemia
• 1°: Parathyroid gland adenoma or
hyperplasia
• 2°: Low calcium e.g. vitamin D deficiency
35
Q

Hypoparathyroidism

A 
• Consequences: hypocalcaemia
• Thyroidectomy
• Autoimmune disease
• Absence or dysfunction of parathyroid
glands
36
Q

Main actions of PTH on target organs

A

bone, kidney, small intestine

37
Q

Main actions of PTH on target organs : bone

A 
 Stimulates calcium release from bones
 ↑ bone resorption (↑ dissolution of CaPO4 crystal)
 rapidcalcium mobilisation from bone
 ↑ serum Ca2+ ↑phosphate (PO4
3-)
38
Q

Main actions of PTH on target organs : kidney

A
  • ↑ Ca2+ reabsorption from DCT
  • ↑ PO43- urinary excretion (inhibit reabsorption)
  • Activates Vit. D
    (Stimulates renal 1α-hydroxylase activity to convert 25-hydroxy vitamin D3 to 1,25-dihydroxy vitamin D3)

Fast-acting: decreasing urinary Ca2+ levels within minutes

39
Q

Main actions of PTH on target organs : small intestine

A

 Indirectly↑ intestinal absorption of Ca2+
through its influence on vitamin D3
-PTH stimulates renal 1α-hydroxylase
activities to activate Vit D3
-Active Vit D3↑ intestinal absorption of Ca2+
by inducing calbindin-D synthesis to
mediates Ca2+ transport

40
Q

Calcitriol (Vitamin D)

A 
Two forms (Vit D2+ D3) are activated to form
calcitriol from 1,25 -DHCC
41
Q

source of vitamin D

A

• Vit D3 (cholecalciferol) – generated in the skin
(UV light), dietary source (dairy produce, fish)
• Vit D2 (ergocalciferol)- derived from fungi, yeast

42
Q

Activation of Vitamin D

A
  • Vit D is obtained either from the skin through the action of sunlight, or from diet
  • Vit D2, D3: biologically inactive
  • Product of these hydroxylation reactions: 1,25- dihydroxyvitamin D3 i.e. calcitriol (metabolically active)
43
Q

↓ [ Ca2+ ] in ECF → ↑ PTH secretion → ↑ 1α-hydroxylase activity

A

↑ Calcitriol

44
Q

Causes of vitamin D

deficiency

A 
-Severe liver or kidney
diseases - interfere with
the generation of active
vitamin D3
-Drugs e.g. anti-epileptic drugs, which interfere with vitamin D metabolism in the liver
-Genetic defects in the
vitamin D receptor
-Insufficient exposure 
to sunlight
-Decreased dietary
intake of vitamin D
45
Q

Vitamin D toxicity

A

Ingestion of excess vitamin D – supplementation

>100ng/mL

46
Q

symptoms of vit d toxicity

A 
– Hypercalcaemia
– Hypercalciuria - calcium excreted in urine resulting in
osmotic diuresis & polyuria
– Kidney stones - deposition of calcium
– Calcification of blood vessels
47
Q

Calcitonin

A 
• Counteracts PTH effect by ↓ serum Ca2+
• Stimulated when Ca2+ serum levels
>2.2mmol/L
• Target organs: bones & kidneys
• Negative loop on Ca2+ serum levels
48
Q

Other hormones affecting Ca2+ homeostasis

A
  1. Sex hormones (estrogens & androgens)
  2. Growth hormones
  3. • Insulin
  4. Glucocorticoids
  5. • Thyroid Hormones
  6. Prostaglandins
49
Q 
Sex hormones (estrogens &
androgens)
A
  • bone resorption (inhibit
    osteoclast; stimulate
    osteoblast)
  • ↑ osteoprotegerin synthesis
50
Q

Growth hormones

A
  • ↑ serum Ca2+ & Ca2+ excretion

in urine

51
Q

• Insulin

A
  • ↑ bone formation
52
Q

Glucocorticoids

A
  • inhibits osteoblast &
    osteoclast activity →
    osteoporosis
  • ↓ Ca2+ absorption in GIT & ↑ Ca2+ excretion in kidney
53
Q

• Thyroid Hormones

A

stimulates hypercalcemia &

hypercalciuria

54
Q

Prostaglandins

A
  • ↑ plasma Ca2+
  • action inhibited by
    glucocorticoids
55
Q

ABNORMALITIES IN PLASMA CALCIUM LEVEL Hypocalcemia

A

cns, cvs, muscle

56
Q

hypocalcemia affects cns

A 
Irritability & Anxiety
Paresthesia (tingling “pins & needles”
sensation)
Seizures
Laryngospasm/Bronchospasm
57
Q

hypocalcemia affects cvs

A

Heart Failure

58
Q

hypocalcemia affects muscle

A 
Muscle cramps (Chovtek’s sign,
tetany)
Hyperactive tendon reflex
59
Q

ABNORMALITIES IN PLASMA CALCIUM LEVEL

hypercalcemia

A

cns, cvs, muscle, kidney + git

60
Q

hypercalcemia affects cns

A

↓concentration, ↑drowsiness

Depression, Confusion & Coma

61
Q

hypercalcemia affects cvs

A

Cardiac Arrythmias

Bradycardia

62
Q

hypercalcemia affects muscle

A

Muscle weakness

Bone pain, kidney stones

63
Q

hypercalcemia affects git & kidney

A

Polyuria, polydipsia (thirst)

Dyspepsia (e.g gastrin )

64
Q

Chvostek’s sign

A 
 Abnormal reaction to the stimulation
of the facial nerve hyperexcitability.
 The facial nerve is tapped at the
angle of the jaw, the unilateral facial
muscles will contract momentarily.
 A positive response varies from
twitching of the lips at the corner of
the mouth to spam of all facial
muscles, depending on the severity of
hypocalcaemia.

Integration finals (19 decks)

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