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CVS > CVS 5 Autonomic Nervous System > Flashcards

CVS 5 Autonomic Nervous System Flashcards

1
Q

What does the autonomic nervous system control?

A

All involuntary actions

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2
Q

Divisions of the autonomic nervous system

A

Parasympathetic - rest + digest
Sympathetic - fight or flight

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3
Q

Describe the preganglionic nerve in the sympathetic nervous system

A

Short
Myelinated

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4
Q

Describe the postganglionic nerve in the sympathetic nervous system

A

Long
Non-myelinated

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5
Q

Describe the preganglionic nerve in the parasympathetic nervous system

A

Long
Myelinated

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6
Q

Describe the postganglionic nerve in the parasympathetic nervous system

A

Short
Non-myelinated

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7
Q

What is released from the preganglionic nerve in the sympathetic nervous system?

A

Acetylcholine

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8
Q

What is released from the postganglionic nerve in most sympathetic nervous system?

A

Noradrenaline

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9
Q

What is released from the preganglionic nerve in the some sympathetic nervous system?

A

Acetylcholine

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10
Q

What is released from the preganglionic nerve in the parasympathetic nervous system?

A

Acetylcholine

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11
Q

What is released from the postganglionic nerve in the parasympathetic nervous system?

A

Acetylcholine

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12
Q

What receptor does acetylcholine from the pregangionic nerve act on?

A

Nicotinic ACh receptors

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13
Q

What receptor does acetylcholine from the postganglionic nerve act on?

A

Muscarinic ACh receptors

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14
Q

What receptor does noradrenaline from the postganglionic nerve act on?

A

Adrenoreceptors

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15
Q

Origins of the sympathetic nervous system

A

Thoracic + lumbar regions of spine

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16
Q

Origins of parasympathetic nerves system

A

Cranial + sacral regions of spine

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17
Q

Describe the action of parasympathetic input into the heart

A
  • Via the vagus nerve
  • Innervate with epicardial surface or SAN + AVN
  • Releases acetylcholine
  • Act on M2 Muscarinic receptors
  • negative chronotropic effect (slows HR)
  • decreases AVN conduction velocity
18
Q

Effect of acetylcholine on heart

A

Negative chronotropic effect (slows HR)
Decreases AVN conduction velocity

19
Q

Describe the sympathetic input to the heart

A
  • From sympathetic trunk
  • Innervates with SAN, AVN + myocardium
  • Releases noradrenaline
  • Act on B1 adrenoreceptor
  • positive chronotropic effect (^ HR)
  • positive inotropic effect (increased force of contraction)
20
Q

What does an positive or negative in chronotropic effect refer to?

A

Heart rate
Positive CE - increase
Negative CE - decrease

21
Q

What does the positive or negative inotropic effect refer to?

A

Force of contraction of heart
Positive IE - increased force
Negative IE - decreased force

22
Q

Effect of noradrenaline on heart

A

Positive chronotropic effect (^ HR)
Positive inotropic effect (^ force of contraction)

23
Q

How does noradrenaline have a positive inotropic effect on the heart ?

A

positive inotropic effect = ^ force of contraction

1- act on B1 adrenoreceptors in myocardium
2- ^ CAMP - activates protein kinase A
3- PKA phosphorylates Ca2+ channels
4- ^ Ca2+ uptake in sarcoplasmic reticulum
5- more Ca2+ for contraction

24
Q

How does noradrenaline have a positive chronotropic effect?

A

1- sympathetic nervous system speeds up relaxation (decreases diastole)
2- decreases time of 1 cardiac cycle
3- increase HR

25
Q

Effect of sympathetic nervous system on SAN

A

Speeds up pacemaker potential
Steeper slope
Increases CAMP

26
Q

Effect of parasympathetic nervous system on SAN

A

Slows down pacemaker potential
Shallower slope
Less CAMP

27
Q

What happens to blood vessels and airways in anaphylaxis?

A

Blood vessels dilate
Airways constrict

28
Q

What is used to treat anaphylaxis?
How does this work?

A

High does of adrenaline injection intramuscularly
- acts on a1 receptors in vessels - vasoconstriction
- increased BP
- acts on B2 receptors in bronchi - bronchodilation
- ^ airflow

29
Q

What receptors do noradrealine act on in vessels?

A

a1 adrenoreceptors

30
Q

What receptors do circulating (normal levels) adrenaline act on in vessels?

A

B2 adrenoreceptors

31
Q

What receptors does high concentrations of adrenaline act on in vessels?
Example of when this may occur

A

a1 adrenoreceptors
e.g. adrenaline injection in anaphylaxis

32
Q

What does activating B2 adrenoreceptors in vessels cause?
Explain why

A

Vasodilation Gs

1- Gs stimulates adenylate cyclase
2- ^ cAMP made
3- PKA activated
4- PKA phosphorylates MLCK
5- MLCK inhibition
5 - Smooth muscle contraction inhibited
6- vasodilation

33
Q

Function of PKA in myocardium

A

Phosphorylates Ca2+ channels
Increase force of contraction

34
Q

Function of PKA in vascular smooth muscle

A

Inhibits MLCK by phosphorlating it&raquo_space; prevents vasoconstriction&raquo_space; vasodilation occurs

35
Q

Describe contraction of vascular smooth muscle

A

1- Ca2+ enter via VGCC or from sarcoplasmic reticulum
2- Ca2+ binds to calmodulin
3- Ca2+ CaM complex activates MLCK
4- MLCK phosphorylates myosin light chain
5- MLC interacts with actin > contraction
6- as Ca2+ levels fall, MLCP dephosphorylates MLC

36
Q

What does activation of a1 adrenoreceptors in vascular smooth muscle cause?
Explain why

A

^ in intracellular Ca2+&raquo_space; Contraction

1- IP3 production
2- release of Ca2+ from SR
3- Ca2+ CaM complex activates MLCK
4- MLCK phosphorylates MLC
5- contraction

1- DAG (diacylglycerol) activated
2- DAG inhibits MLCP

37
Q

What does activation of B1 adrenoreceptors in vascular smooth muscle cause?
Explain why

A

promotes relaxation

1- adenylate cyclase activation
2- cAMP produced
3- PKA activated
4- PKA phosphorylates MLCK
5- MLCK inhibited
6 - decrease in MLC phosphorylation
7- relaxation + less contraction

38
Q

Where are baroreceptors found?

A

Aortic arch
Carotid sinus

39
Q

Explain how baroreceptors respond to an increase in arterial pressure

A

1- ^ arterial pressure causes stretch
2- stretch detected by baroreceptors
3- impulse sent to medulla oblongata
4- sends signal to decrease HR + contractility
5- BP decreases

40
Q

What effect do local metabolites have on circulation?

A

Increase in metabolites leads to vasodilation which increases flow

CVS (17 decks)

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