Autonomic nervous system

Question 1

what is the autonomic nervous system concerned with

Answer 1

control of internal environment, works together with endocrine system to maintain homeostasis

Question 2

main functions of autonomic nervous system

Answer 2

controls functions not under voluntary control
innervates smooth muscle, cardiac muscle and glands
regulates visceral functions - heart rate, BP, digestion, urination
general motor division of PNS

Question 3

what is homeostasis

Answer 3

dynamic balance between autonomic branches

Question 4

what are the 2 branches of the autonomic NS

Answer 4

sympathetic (fight, flight or fright)
parasympathetic (rest and digest)

Question 5

what are the funtions of the sympathetic nervous system

Answer 5

pupil dilation, elevation of lid
increased rate and force of heart contractions
bronchodilator
vasoconstriction in gut and skin
vasodilation of coronary arteries
decreased glandular secretions
glycogen is converted to glucose
increases sweat production
closes sphincter/bladder wall relaxes
closes sphincter/constipation

Question 6

functions of parasympathetic NS

Answer 6

focusing of eye to maintain clear image (accommodation), drooping of upper eyelid (ptosis)
decrease rate and force of contraction of heart
bronchoconstriction
vasodilation in gut and skin
increased glandular secretions
stimulates release of bile
decreases sweat production
opens sphincter/bladder contraction
closes sphincter/peristalis

Question 7

what is the anatomy of the sympathetic NS

Answer 7

arises from the thoracolumbar region of the CNS
chain of two motor neurons (pre and post-ganglionic)
conduction is slower due to thinly/unmyelinated axons

Question 8

what is the anatomy of the parasympathetic NS

Answer 8

arises from craniosacral division of CNS
chain of two motor neurons (pre and post-ganglionic)
conduction is slower due to thinly/unmyelinated axons

Question 9

what are the preganglionic neurotransmitters

Answer 9

acetylcholine is released by both the sympathetic and parasympathetic
cholinergic-nicotinic receptors

Question 10

what are the postganglionic neurotransmitters

Answer 10

sympathetic most release noradrenaline via adrenergic receptors
parasympathetic most release acetylcholine via muscarinic receptors

Question 11

describe the cranial outflow of the PNS

Answer 11

comes from brain
cell bodies located in cranial nerve nuclei in the brainstem
innervates organs of the head, neck, thorax and abdomen

Question 12

what do preganglionic fibres run via in head and neck

Answer 12

oculomotor nerve (III)
facial nerve (VII)
glossopharyngeal nerve (IX)
vagus nerve (X)

Question 13

describe outflow via the vagus nerve

Answer 13

fibres innervate visceral organs of the thorax and abdomen
stimulates digestion, reduction in heart rate and BP
preganglionic cell bodies are located in dorsal motor nucleus in the medulla
ganglionic neurons are confined withing the walls of the organs being innervated

Question 14

sacral outflow of the PNS

Answer 14

supplies remaining abdominal and pelvic organs
emerges from s2-4
preganglionic cell bodies are located in visceral region of spinal grey matter
form the splanchnic nerves

Question 15

organisation of sympathetic NS

Answer 15

basic organisation
issues form t1-12
preganglionic fibres form the lateral grey horn
supplies visceral organs and structures of superficial body regions
contains more ganglia than the parasympathetic division

Question 16

function of alpha 1 receptors

Answer 16

located in smooth muscle in arterioles
cause vasoconstriction

Question 17

function of alpha 2 receptors

Answer 17

located on coronary arteries
causing vasodilation

Question 18

function of beta 1 receptors

Answer 18

located on cardiac muscles
lead to increased contractility

Question 19

beta 2 receptor function

Answer 19

located in sino atrial node, some smooth muscle in arterioles (esp skeletal), and, smooth muscle of bronchi
increases heart rate
causes vasodilation and bronchodilation

Question 20

what is the central control of the ANS

Answer 20

brainstem
spinal cord
hypothalamus
amygdala
cerebral cortex

Question 21

how does the brainstem and spinal cord control the ANS

Answer 21

reticular formation exerts the most direct influence
medulla oblongata
periaqueductal grey matter

Question 22

how does the hypothalamus and amygdala control the ANS

Answer 22

hypothalamus is the main integration centre of ANS
amygdala is the main limbic region from emotions

Question 23

test for ANS abnormality

Answer 23

pupil reactions
postural BP responses
variation of heart rate with deep breathing (sinus arrhythmia)
lacrimal function

Question 24

describe vasovagal syncope

Answer 24

simple faint
seen commonly in young people with no underlying illness
when sudden vasodilation occurs, peripheral resistance decreases in arterioles and BP falls while cardiac rate fails to increase

Question 25

associated features of vasovagal syncope

Answer 25

if vagal stimulation occurs it leads further bradycardia and perspiration, increased peristalsis, yawning, nausea, pallor and salivation

Question 26

describe orthostatic hypotension

Answer 26

similar to vasovagal syncope
brought on when getting up from reclined position or standing still for long periods of time
steady fall in BP without a compensatory increase in cardiac rate
mild staggering or falling may precede loss of consciousness