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Flashcards in review of the sympathetic nervous system Deck (66)
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1
Q

where does the cell body of preganglionic neuron lie generally?

A

in the brain or spinal cord

2
Q

where do axons of the preganglionic neuron go?

A

through white ramps to get to sympathetic ganglia where it synapses with a postganglionic neurone

3
Q

what is another name for preganglionic neuron?

A

visceral motor neuron

4
Q

what are sympathetic ganglia?

A

sites of synapses between pre and post ganglionic neurons

5
Q

where does the sympathetic trunk ganglia lie?

A

either side of the vertebral column

6
Q

what makes up the sympathetic chain?

A

sympathetic ganglia and sympathetic trunk

7
Q

where does the postganglionic neutron lie?

A

outside the CNS in the PNS

8
Q

where does the cell body of a postganglionic neuron lie?

A

in autonomic ganglia

9
Q

where do postganglionic axons terminate?

A

visceral effectors (mainly to smooth muscle surrounding blood vessels)

10
Q

where do the cell bodies of preganglionic neurons in the thoracolumbar division lie?

A

the lateral horns of the grey matter

11
Q

which vertebral segments make up the thoracolumbar division?

A

12 thoracic segments

first 2 lumbar segments

12
Q

what is the thoracolumbar outflow?

A

axons of the preganglionic neurons of the thoracolumbar division

13
Q

name the three cervical ganglia

A

superior, middle and inferior cervical ganglia

14
Q

what does the superior cervical ganglia innervate and what action does this bring around?

A

innervates iris of the eye, skin of face and salivary gland

causes pupil dilation, blushing and reduction of saliva

15
Q

what are the cervical ganglia attached to?

A

thoracic chain below

16
Q

what does the cardiac plexus do?

A

provides sympathetic innervation of the heart

plexus forms around the aorta and atria

17
Q

what nerves make up the cardiac plexus?

A

branches of the upper thoracic chain

18
Q

what does the pulmonary plexus do?

A

sympathetic innervation of the lungs

plexus forms around the large pulmonary arteries

19
Q

what neurotransmitter do preganglionic neurons release and what effect does it have?

A

acetylcholine

activates postganglionic

20
Q

what type of receptors are on autonomic ganglia?

A

cholinergic nicotinic types

21
Q

what neurotransmitter do postganglionic neurons release and what effect does it have?

A

noradrenaline

makes arterial smooth muscle contract

22
Q

what receptors on smooth muscle does noradrenaline act on?

A

alpha-1 adrenoreceptors

23
Q

what additions to the sympathetic chain are there below the diaphragm?

A

prevertebral ganglia

24
Q

what makes up the prevertebral ganglia?

A

celiac plexus

superior and inferior mesenteric ganglion

25
Q

what are the greater and lesser splanchnic nerves?

A

long preganglionic sympathetic axons to the celiac and mesenteric ganglia

26
Q

what does the coeliac plexus supply?

A

vasoconstrictor nerves to the stomach and duodenum

27
Q

what does the superior mesenteric plexus supply?

A

ascending and descending colon

28
Q

what does the inferior mesenteric plexus supply?

A

bladder and reproductive organs

29
Q

where are the adrenal glands found?

A

on top of the kidneys

30
Q

what are the names of the outer and inner parts of the adrenal glands?

A

outer - cortex

inner - medulla

31
Q

describe how adrenaline is made from tyrosine

A

tyrosine –> DOPA –> dopamine + OH –> noradrenaline + methyl –> adrenaline

32
Q

what are catecholamines and name the main ones?

A

hormones produced by the adrenal glands

dopamine, noradrenaline and adrenaline

33
Q

which sympathetic neurons are noradrenergic?

A

sympathetic post ganglionic apart from the sweat glands

34
Q

which hormone do sweat glands use?

A

acetylcholine

35
Q

how does the sympathetic NS regulate the distribution of blood around the body?

A

active at all times
ongoing amounts of vasoconstriction
operates at a low level when youre resting or stressed

36
Q

give an example of drugs that block the resting tone of sympathetic output

A

alpha blockers like prazosin

37
Q

what are side effects of alpha blockers?

A

postural hypotension

38
Q

what is postural hypotension and how does it occur?

A

when you faint when you stand up

body cannot increase vasoconstrictor tone in leg muscle when you stand up so the BP drops and you faint

39
Q

what adrenoreceptors are found in the brain and heart?

A

beta-adrenoreceptors

40
Q

explain how and why sympathetic activity increases during exercise

A

exercising muscle release local chemical vasodilators
vasodilation would cause low bp and drop in total peripheral resistance

sympathetic outflow increases at start of exercise

global vasoconstriction via noradrenaline esp of non-exercising muscle

cardiac output redirected to exercising muscle

total peripheral resistance is maintained

41
Q

what are adrenoreceptors?

A

receptors for adrenaline and noradrenaline

42
Q

what are the types of adrenoreceptors?

A

alpha - a1, a2

beta - b1, b2, b3

43
Q

what types of receptors does noradrenaline act on?

A

alpha

44
Q

what action does alpha 1 receptors bring about?

A

increases contraction

45
Q

what receptor is mainly found on vascular smooth muscle?

A

alpha 1

46
Q

what do alpha 1 antagonists do?

A

reduce blood pressure

47
Q

give an example of an alpha 1 antagonist

A

prazosin

48
Q

what action does alpha 2 receptors bring about?

A

reducing noradrenaline release by negative feedback
inhibit insulin release in the pancreas
stimulate glucagon release
contraction of sphincters of gastrointestinal tract
increased thrombocyte aggregation

49
Q

what receptors are found on presynaptic sympathetic nerve terminals?

A

alpha 2

50
Q

what do alpha 2 agonists do?

A

reduce blood pressure by inhibiting noradrenaline release

51
Q

give an example of alpha 2 agonist

A

clonidine

52
Q

what type of receptors does adrenaline act on?

A

beta

53
Q

what do beta 1 receptors do and where are they found?

A

increase fore and rate of contraction of myocardium

found mainly on heart and kidneys

54
Q

what do beta 2 receptors do and where are they found?

A

relax muscle

found mainly in bronchial smooth muscle, gastrointestinal tract, liver and uterus

55
Q

what do beta 3 receptors do?

A

increase lipolysis and gluconeogenesis in adipose tissue

56
Q

what receptors are beta blockers selective for?

A

beta 1

57
Q

what are beta blockers used to treat?

A

manage abnormal heart rhythms
prevent second heart attack
reduce HR and force of contraction in hypertensive patients

58
Q

what are side effects of beta blockers?

A
bronchoconstriction
fatigue
dizziness
depression
loss of libido
exacerbating diabetes
59
Q

why are beta blockers not the first choice of treatment for hypertension?

A

not as effective as diuretics, ACE inhibitors and calcium channel blockers

60
Q

what is the effect of blocking beta 2 and beta 3 receptors?

A

exacerbating diabetes

61
Q

what does salbutamol do?

A

relaxes bronchial smooth muscle in asthmatics by acting on beta 2 receptors

62
Q

how does the sympathetic nervous system react in severe blood loss?

A

arterial vasoconstriction in non-essential organs to maintain BP and perfusion of vital organs
kidneys release renin to maintain blood pressure
ADH stimulated to reduce urine output

63
Q

what do alpha receptors do in severe blood loss?

A

causes smooth muscle to constrict

platelets become more sensitive to collagen to increase clotting

64
Q

what does cortisol do?

A

stimulates adrenaline and noradrenaline synthesis

65
Q

how is cortisol released

A

psychological stressors activate the sympathetic NS and the hypothlaamo-pituitary-adrenal axis
HPA releases adrenocorticotrophic hormone
ACTH stimulates cortisol release from adrenal cortex

66
Q

where is cortisol released from

A

adrenal cortex