Session 8.1: Structure of the ANS

Question 1

what does autonomic mean

Answer 1

self governing

Question 2

what does the ANS do

Answer 2

controls vegetative (involuntary function) eg: heart rate, blood pressure, GI motility, iris diameter

Question 3

where is the ans situated

Answer 3

separate from the voluntary (somatic) motor system
peripheral
it is entirely efferent (but regulated by afferent inputs)

Question 4

what are the role of sensory neurons in regulating inputs to the ANS

Answer 4

they monitor levels of CO2, O2, nutrients, arteriole pressure and GI content and chemical composition

Question 5

what monitors the blood O2, CO2 and pH

Answer 5

carotid body, chemoreceptors at the bifurcation of the cartoid artery, information is passed to CNS via glossopharyngeal nerve

Question 6

what is the purpose of the nucleus tractus solitarius

Answer 6

integrates afferent information to appropriate efferent autonomic output
and receives inputs from area postrema which detects toxins in blood and cerebrovascular fluid and induced vomitting and taste aversion

Question 7

how if the nucleus tractus solitarius formed

Answer 7

primary sensory neurons project on to ‘second order’ sensory neurons located in medulla oblongata

Question 8

what is the role of sensory inofrmation

Answer 8

constantly modulates the activity of the efferent neurons of the ANS

Question 9

what are the two divison of autonomic nervous system

Answer 9

parasympathetic

symapthetic

Question 10

what is the role of sympathetic NS

Answer 10

responds to stressful situations - fight or flight

increases HR, increase force of contraction, increase BP

Question 11

what is the role of the parasympathetic NS

Answer 11

regulates basal activities eg: basal heart rate…rest and digest

Question 12

what is the structure of the ANS

Answer 12

efferent system originates from brain and spinal cord, the spinal cord is divided into anatomic divisions:
Medullary
Cranial
Thoraic
Lumbar
Sacral (may now be classified as sympathetic)

Question 13

where is the sympathetic nerve fibres originate from

Answer 13

the cell bodies of the sympathetic NS emerging from CNS originate from thoracic and lumbar regions

Question 14

where is the parasympathetic nerve fibres originate from

Answer 14

cell bodies emerge from CNS lie in medullary and sacral regions of spinal cord

Question 15

what is the parasympathetic nerve numbered 10 and what is the role of the nerve

Answer 15

vagus nerve

carries info from CNS-> heart, lungs GI tract

Question 16

what is the general structure of the parasympathetic NS and sympathetic NS

Answer 16

cell bodies lie within CNS -> axon (preganglionic)-> ganglion -> second neuron’s axon (post ganglionic) -> projector tissue

Question 17

where do we get communication in the periphery

Answer 17

ganglia

Question 18

what is a key feature of pre ganglionic fibres

Answer 18

myelinated

Question 19

what is a key feature of post ganglionic fibres

Answer 19

unmyelinated

Question 20

what are the key features of parasympathetic NS

Answer 20

long myelinated preganglionic fibres
short unmyelinated postganglionic fibres
ganglia located in innervated tissues
actions oppose that of the sympathetic NS

Question 21

what are the key features of sympathetic NS

Answer 21

short myelinated preganglionic fibres
long unmyelinated postganglionic fibres
ganglia located in paravertebral chain close to spinal cord
actions oppose parasympathetic actions

Question 22

what is the third division of the autonomic NS

Answer 22

enteric - controls GI system
has sympathetic and parasympathetic inputs but are capable of operating independly of CNS
local circuitry - co ordinate responses