The Autonomic Nervous System and the CVS Flashcards Preview

ESA 2- Cardiovascular System > The Autonomic Nervous System and the CVS > Flashcards

Flashcards in The Autonomic Nervous System and the CVS Deck (162):
1

What is the ANS important for?

Many physiological functions

2

Give 4 physiological functions the ANS is responsible for?

Heart rate
Blood pressure
Body temperature 
Co-ordinating the body’s response to exercise and stress

3

What does the ANS exert control over?

Smooth muscle 
Exocrine secretion
Rate and force of contraction of heart

4

What smooth muscle is under ANS control?

Vascular 
Visceral

5

What are the two divisions of the ANS?

Parasymphathetic
Sympathetic

6

What is the division of the ANS based on?

Anatomical grounds

7

What is sometimes given as the third division of the ANS?

Enteric

8

What is the enteric division?

A network of neurones surrounding the GI tract

9

What is the enteric division normally controlled via?

Sympathetic and parasympathetic fibres

10

How are the sympathetic and parasympathetic systems organised?

Two neurones are arranged in series. 
One starts in the CNS 
The two neurones synapse in the peripheral nervous system

11

Where is the cell body of the preganglionic neurone?

In the CNS

12

Where is the cell body of the postganglionic neurone?

In the PNS

13

Give 12 organs innervated by the sympathetic nervous system

Eyes
Blood vessels 
Salivary glands 
Heart
Lungs
Adrenal medulla 
Liver
GI tract
Bladder
Genitalia
Blood vessels
Sweat glands

14

Give 9 organs innervated by the parasympathetic nervous system, and what nerve innervates them

Eye- III
Lacrimal glands- VII
Salivary glands- IX
Heart- X
Lungs- X
Upper GI tract- X
Lower GI tract- Nervi erigentes 
Bladder- Nervi erigentes 
Genitalia- Nervi erigentes

15

What is the origin of the sympathetic division?

Thoracolumbar origin

16

Where do the preganglionic neurones of the sympathetic division arise from?

Segments T1 to L2 (or L3)

17

Where do most preganglionic neurones in the sympathetic division synapse with postganglionic neurones?

In the paravertebral chain of ganglia

18

Which sympathetic nerve synapse in a number of prevertebral ganglia?

Coeliac 
Superior mesenteric 
Inferior mesenteric ganglia

19

What is the original of parasympathetic nerve?

Craniosacral

20

What is meant by craniosacral?

Medulla part of brain stem and region of spinal cord

21

Where do preganglionic parasympathetic nerves travel?

In cranial nerves (III, VII, IX and X), or sacral outflow from S2-S4

22

Where do parasympathetic preganglionic synapse?

In ganglia close to target tissue

23

How long are the postganglionic neurones of the parasympathetic division?

Short

24

What do preganglionic neurones release?

Acetylcholine (ACh)

25

What is ACh?

An excitatory neurotransmitter

26

What do ACh do?

Acts on certain nicotinic acetylcholine receptors in postganglionic membranes

27

What do nicotinic ACh receptors have?

An integral ion channel that permeable to K and Na ions

28

What does the ion channel in nicotinic ACh receptors cause?

An overwhelming influx of Na ions, causing depolarisation and therefore the firing of an action potential

29

What are postganglionic sympathetic neurones usually?

Noradrenergic

30

What is meant by noradrenergic?

Use noradrenaline as a transmitter

31

What are postganglionic parasympathetic neurones usually?

Cholinergic

32

What is meant by cholinergic?

Have ACh as a transmitter

33

What is the exception to sympathetic neurones being noradrenergic?

Sympathetic innervation of sweat glands, where postganglionic neurones release ACh, which acts on muscarinic ACh receptors

34

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

ACh

35

What happens to ACh once it has been released from the preganglionic neurone?

It is picked up by nicotinic ACh receptors on the postganglionic neurone

36

Is it always ACh that is released from preganglionic neurones in the SNS?

No

37

What is released from the postganglionic neurone in the SNS?

Noradrenaline

38

What happens to noradrenaline one it’s been released from the postganglionic neurone?

It’s picked up by adrenergic receptors on effector cells

39

Where are chromaffin cels located?

In the adrenal medulla

40

What are chromaffin cells?

Like specialised postganglionic sympathetic neurones

41

What do adrenal chromaffin cells do?

Release adrenaline, which circulates in the blood stream as a hormone

42

What do noradrenaline and adrenaline act on?

Adrenoreceptors called G protein-coupled receptors

43

Do G protein-coupled have an integral ion channel?

No

44

How do G protein-coupled receptors differ in their response to adrenaline to noradrenaline?

They respond with different affinities

45

What are the types of adrenoreceptors?

α and ß

46

What are the subtypes of α adrenoreceptor?

α1
α2

47

What are the subtypes of ß adrenoreceptors?

ß1
ß2
Other subtypes exist

48

What can different tissues have with respect to adrenoreceptors?

Different subtypes

49

What do different subtypes of adrenoreceptors allow?

Diversity of action 
Selectivity of drug action

50

What are co-transmitters?

Other transmitters that are released with noradrenaline or adrenaline at synapse of post-ganglionic neurone with effect cells

51

Give two examples of co-transmitters

Neuropeptide Y
ATP

52

What is released from the preganglionic neurone in the PNS?

ACh

53

What happens to ACh in the PNS once its been released from the preganglionic neurone?

Its picked up by nicotinic ACh receptor on the postganglionic neurone

54

What is released from the postganglionic neurone in the PNS?

ACh

55

What happens once ACh has been released from the postganglionic neurone in the PNS?

It is picked up by muscarinic ACh receptor on effector cell

56

What kind of receptors are the muscarinic ACh receptors?

G protein-coupled receptors

57

What subtypes of G protein-coupled receptors are the muscarinic ACh receptors?

M1, M2 and M3

58

What happens when parasympathetic and sympathetic divisions both innervate a tissue?

They often have a opposite effect

59

When is sympathetic activity increased?

Under stress

60

When is parasympathetic activity more dominant?

Under basal conditions

61

What do the PNS and SNS work together to do?

Maintain balance

62

Give 5 examples of SNS control

Dilation of pupil of eye 
Relaxation of lungs
Rate and force of contraction of heart increases
Localised secretion from sweat glands
Generalised secretion from sweat glands

63

How does the pupil of the eye dilate?

Contraction of radial muscle

64

What does dilation of the pupil use?

α1 receptor

65

What does relaxation of the airways of the lungs use?

ß2 receptor

66

What does the control of rate and force of contraction of the heart use?

ß1 receptor

67

What does localised secretion from sweat glands use?

α1 receptor

68

What does generalised secretion from sweat glands use?

M3 receptor

69

Give 3 examples of things controlled by the PNS

Contraction of the pupil 
Contration of the airways 
Decrease in the heart rate

70

How does the pupil contract?

Contraction of sphincter muscle

71

What does contraction of the pupil use/

M3 receptor

72

What does contraction of airways in the lungs use?

Usually M3 receptor

73

What does the PNS use to decrease heart rate?

M2 receptor

74

Where is sympathetic drive different?

In tissues that are independently regulated

75

What does the ANS control in the CVS?

Heart rate 
Force of contraction of heart
Peripheral resistance of blood vessels

76

What does the ANS not do in the CVS?

Initiate electrical activity in the heart

77

What happens to a denervated heart?

It still beats, but at a faster rate

78

What is the heart under at rest?

Vagal influence

79

What supplies PNS input into the heart?

10th (X) cranial nerve vagus

80

Where does the PNS preganglionic fibre inputting to the heart synapse with postganglionic cells?

On the epicardial surface, or within the walls of the heart at the SA and AV node

81

What is the result of the synapse of the nerve supplying the heart being where it is?

It allows time for the atria to fully contract

82

What do postganglionic cells of the PNS in the heart nerves release?

ACh

83

What does ACh act on in the heart?

M2 receptors

84

What is effect of ACh on the heart?

Decreases heart rate
Decrease AV node conduction velocity

85

What is the effect of a decrease in heart rate called?

A negative chronotropic effect

86

Where do the postganglionic fibres for the SNS input into the heart from?

The sympathetic trunk

87

What does the SNS input into the heart innervate?

SA node, AV node and myocardium

88

What does SNS activation of the heart cause?

Release of noradrenaline

89

Where does noradrenaline act in the heart?

Mainly ß1 adrenoreceptors

90

What is the effect of noradrenaline in the hear?

Positiv chronotropic effect (increases heart rate) 
Increases force of contraction

91

What is the effect of an increase of contraction called?

Positive inotropic effect

92

Other than ß1, what other adrenoreceptors are present in the heart?

ß2 and ß2, but the main effect is mediated by ß1 receptors

93

What are the autonomic inputs into the heart?

Medulla oblongata sympathetic motor neurone 
Motor vagus nerve (cranial nerve X, PNS)
Sensory vagus nerve
Sensory glossopharyngeal (cranial nerve IX)

94

Where does the medulla oblongata sympathetic motor neurone go?

From the cardiovascular centre and to the spinal cord

95

Where does the medulla oblongata sympathetic motor neurone synapse?

The spinal cord

96

What does the medulla oblongata sympathetic motor neurone synapse with?

The cardiac accelerator nerve in the sympathetic trunk ganglion

97

What does the medulla oblongata sympathetic motor neurone innervate?

The ventricular myocardium, the AV node, and the SA node

98

What does the motor vagus nerve innervate?

SA node and AV node

99

What does the sensory vagus nerve innervate?

Baroreceptors in the arch of the aorta

100

What does the sensory glossopharyngeal nerve innervate?

Baroreceptors in the carotid sinus

101

What is the pacemaker of the heart?

Cells in the SAN

102

What do cells in the SAN do?

Steadily depolarise towards towards threshold- the slow depolarising pacemaker potential

103

What happens in the pacemaker potential?

There is turning on of a slow Na conductance, called the funny current. 
Opening of Ca channels

104

What sets the rhythm of the heart?

AP firing in the SA node

105

What effect does sympathetic activity have on the pacemaker potential?

It increases the slope of the pacemaker potential

106

What is the effect of the SNS on the pacemaker potential mediated by?

ß1 receptors that are G-protein coupled receptors

107

How do ß1 receptors mediate the effect of the SNS on the pacemaker potential?

They increase cAMP production by stimulating adenyl cyclase.

108

What effect does parasympathetic activity have on the pacemaker potential?

In decrease the slope

109

What is the effect of the PNS on the pacemaker potential mediated by?

M2 receptors, which are G protein-coupled receptors

110

How do M2 receptors mediate their effect on the pacemaker potential?

They increase K conductance, and decrease cAMP by inhibiting adenyl cyclase. K brings the membrane potential down, further from threshold

111

What effect does noradrenaline have on the force of contraction?

It increases it

112

How does noradrenaline exert its effect on the force of contraction?

It acts on ß1 receptors in the myocardium, which causes an increase in cAMP, activating protein kinase A

113

How does the activation of PKA lead to an increased force of contraction?

Phosphorylation of Ca channels open them, increasing Ca entry during the plateau of the AP. 
This leads to an increased uptake of Ca into the SR 
Leads to increased sensitivity of contractile machinery to Ca

114

How does increased uptake of Ca into the SR increase the force of contraction?

It increases build up, so there is more Ca to be released 
Increased uptake reduced duration of contraction, which is necessary if need the heart to fire at a faster rate

115

What do most vessels receive?

Sympathetic innervation

116

What vessels do not receive sympathetic innervation?

Apart from some specialised tissue, such as erectile tissue, which receives parasympathetic tissue

117

What receptors do most arteries and veins have?

α1 adrenoreceptors

118

What vessels also have ß2 receptors?

Coronary, liver and skeletal muscle vasculature

119

How does the affinity of circulating adrenaline differ between α1 and ß2 receptors?

It has a higher affinity for ß2 receptors

120

What does adrenaline do at physiological concentrations?

Preferentially bind to ß2 adrenoreceptors

121

What will adrenaline do at higher concentrations?

Activate α1 receptors

122

What does vasomotor tone allow for?

Vasodilation to occur

123

What leads to vasodilation?

Decreased sympathetic output

124

What leads to vasomotor tone?

Normal sympathetic output

125

What leads to vasoconstriction?

Increased sympathetic output

126

What effect does activating ß2 receptors have on vessels?

It causes vasodilation

127

How does activation of ß2 receptors lead to vasodilation?

Causes an increase in cAMP, which activates PKA. This opens K channels, and inhibits MLCK, leading to relaxation of smooth muscele

128

What effect does activating α1 receptors have on vessels?

Causes vasoconstriction

129

How does activation of α1 receptors cause vasoconstriction?

It stimulates IP 3  production, causing an increase in intracellular [Ca] from stores and via influx of extracellular calcium, causing contraction of smooth muscle

130

What does active tissue produce?

More metabolites

131

Give 4 examples of metabolites produced by active tissues

Adenosine 
K+
H+
Increased PCO 2

132

What effect do local increases in metabolites have?

Strong vasodilator effect

133

What is the effect of local metabolites on vasodilation important for?

Ensuring adequate perfusion of skeletal and coronary muscle

134

How are changes in the state of the CVS communicated to the brain?

Via the afferent nerves

135

What detects changes in the state of the CVS?

Baroreceptors
Atrial receptors

136

What are baroreceptors involved in?

The high pressure side of the system

137

What are atrial receptors involved with?

The low pressure side of the system

138

What are cardiac baroreceptors?

Nerve endings in the carotid sinus and aortic arch that are sensitive to stretch

139

What stretches the baroreceptors?

Increased arterial pressure

140

What happens when baroreceptors detect an increase in blood pressure?

It communicates this to the medulla via the afferent pathway. 
The coordinating centre of the medulla then sends efferent signals to the heart and the vessels, causing bradycardia and vasodilation

141

What are the effects of bradycardia and vasodilation?

Counteracts the increased mean arterial pressure

142

What are the types of drugs that act on the CVS?

Sympathomimetics 
Adrenoreceptor antagonists 
Cholinergenics

143

What do sympathomimetics do?

Mimic the action of the sympathetic nervous system

144

What are the types of sympathomimetics?

α-adrenoreceptor agonists 
ß-adrenoreceptor agonist

145

What are cardiovascular uses of sympathomimetics?

Administration of adrenaline to restore function in cardiac arrest 
Dobutamine (ß1 agonist) may be given in cardiogenic shock (pump failure) 
Adrenaline administered for anaphylatic shock

146

Give a non-cardiovascular use for sympathomimetics?

ß2 agonist (salbutomal) used in treatment of asthma

147

What does salbutamol cause?

Relaxation of bronchiole smooth muscle

148

What do α-adrenoreceptor antagonists do?

Prevents constriction, therefore dilation, therefore decreases pressure

149

Why can α-adrenoreceptor antagonists be used as an anti-hypertensive agent?

Because they inhibit NA action on vascular smooth muscle

150

Give an example of an α1-adrenoreceptor antagonist

Prazosin

151

Give two examples of ß-adrenoreceptor antagonists

Propranalol
Atenolol

152

What does propranolol do?

Activates both ß receptors, leading to slowed heart rate and reduced force of contraction (ß1), and acts on bronchial smooth muscle (ß2), leading to bronchoconstriction

153

Why is propranolol dangerous for use with asthmatics?

It’s not selective

154

What is atenolol selective do?

ß1, and therefore the heart

155

What are the types of cholinergics?

Muscarinic agonists 
Muscarinic antagonists

156

What do muscarinic agonists do?

Activate the receptors

157

Give an example of a muscarinic agonist

Pilocarpine

158

What is pilocarpine used in?

The treatment of gluacacoma

159

What is glaucacoma?

Pressure build up in eyeball

160

Why is pilocarpine used in the treatment of glucacoma?

It activates constrictor pupillae muscle, and so drains and reduces pressure in the eye

161

Give two examples of muscarinic antagonists

Atropine 
Tropicamide

162

What are muscarinic antagonists used to do?

Increase heart rate
Bronchial dilation- used to dilate pupils for examination of eye