Automatic nervous system

Question 1

What is the autonomic nervous system?

Answer 1

• part of the efferent division of the peripheral nervous system

Question 2

What is the function of the autonomic nervous system?

Answer 2

• It regulates involuntary processes eg breathing, swallowing, digestion , arousal

Question 3

what is an autonomic gangalion?

Answer 3

• a cluster of cell bodies in the ANS
• where pre ganglion and post ganglion neurons synapse

Question 4

Compare and contrast somatic neurons with autonomic neurons

Answer 4

• ANS - 2 neurons, pre ganglion and post ganglion, innervates smooth muscle, glands etc - can be excitation or inhibition
• somatic NS - uses a single motor neuron to innervate skeletal muscle ( alpha), only excitation

Question 5

What are the functions of the 2 divisions of the ANS?

Answer 5

1. Sympathetic - flight or fight response - eg increases heart rate, dilates pupils, inhibits digestion
2. Parasympathetic - rest or digest - lowers heart rate, contracts pupils, promotes digestion

Question 6

Describe the pre and post ganglion neurons in the sympathetic system

Answer 6

• preganglia neurons come from thoraic and lumbar regions of spine
• sympathetic ganglia lie close to spinal chord
• neurons arising from lumbar segment will stimulate noradrenaline production

Question 7

Describe the pre and post ganglion neurons in the parasympathetic system

Answer 7

• preganglionic neurons exit the brain and spinal chord through the cranial nerves
• preganglionic neurons synapse with post ganglionic neurons in ganglia close to the organs ( nerve X)

Question 8

What are collateral/prevertebral ganglia?

Answer 8

• Lie between the sympathetic ganglia and the target organ

Question 9

What neurotransmitter does the parasympathetic neuron use?

Answer 9

Acetylcholine

Question 10

What neurotransmitters does the sympathetic system use?

Answer 10

Acetylcholine and Noradrenaline

Question 11

Compare neurotransmitters and synapses in symp vs parasymp

Answer 11

1. All preganglionic neurons use acetylcholine as neurotransmitter ( & nicotinic receptors)
2. Most postganglionic sympathetic neurons release noradrenaline
3. Most postganglionic parasympathetic neurons release Ach

Question 12

Contrast the structure of preganglionic neurons and post ganglionic neurons in symp and parasymp system

Answer 12

• preganglionic neurons are myelinated (short in symp and long in para symp)
• Post ganglionic neurons are not myelinated (short in parasymp and long in symp)

Question 13

What receptors do effector target muscle/gland have for parasympathetic system

Answer 13

Muscarnic

Question 14

What receptors do the effector muscle/gland have for symp system?

Answer 14

• Adrenergic receptors

Question 15

What are adrenergic receptors and what are the 3 subtypes ?

Answer 15

Class of G protein coupled receptors that are targets of noradrenaline etc

3 subtypes are

• Alpha 1
• Alpha 2
• Beta

Question 16

Compare the anatomical difference between somatic neurons and where they lie vs autonomic nuerons

Answer 16

• somatic : cell bodies of motor neurons reside in CNS ( brain or spinal chord) & their axons extend all the way to skeletal muscles
• autonomic : chains of 2 motor neuron, preganglionic lies in brain or spinal chord, postganglionic lies in cell body outside CNS

Question 17

what is the parasympathetic nervous system also called?

Answer 17

• the craniosacral system - because all of its preganglionic neurons are in the brain stem or sacral levels of spinal chord

Question 18

what is the sympathetic nervous system also called?

Answer 18

• thoracolumbar system because all of its neurons are in lateral horn of gray matter from T1-L2

Question 19

What gland is an exception?

Answer 19

• the adrenal gland
• the neurons synapse in the gland which causes an ‘adrenaline rush or surge’

Question 20

what is the ‘central control’ of the ANS?

Answer 20

• The Amygdala
• the main region for emotions
• function: stimulates sympathetic activity ( esp previous learnt fear related activity)

Question 21

Give 2 diseases associated with the ANS

Answer 21

1. Raynaud’s disease - hyperactivation of the sympathetic NS causing extreme vasoconstriction
2. Horner’s syndrome - group of nerves @ sympathetic trunk are damaged - loss of sweating, vasodilation