Lec 18: Autonomic nervous system

Question 1

What neurotransmitters are involved in the sympathetic nervous system and what receptors are involved?

Answer 1

Noreadrenaline, adrenergic receptors

Question 2

What neurotransmitters are involved in the parasympathetic nervous system and what receptors are involved?

Answer 2

Acetylcholine, muscarininc receptors

Question 3

What muscles are normally contracted?

Answer 3

Sphincters

Question 4

What muscles are normally partially contracted

Answer 4

Blood vessels, airways

Question 5

What muscles are phasically active?

Answer 5

Stomach, intestines

Question 6

What muscles are normally relaxed?

Answer 6

Esophagus, bladder

Question 7

What is the autonomic nervous system, what does it do and what neruons does it contain?

Answer 7

Its part of the PNS and conducts impulses away from the CNS. It helps regulate the activities of glands, smooth muscle and cardiac muscle. It has preganglionic (cell bodies in spinal chord and brain stem) and postganglionic (cell bodies in autonomic ganglia) neurons

Question 8

Give some info about PNS somatic vs autonomic divisions

Answer 8

Somatic: consists of a single neuron between CNS and skeletal muscles, innervates (supplies nerves to) skeletal muscles, can only lead to muscle excitation.
Autonomic: Has two neuron chain (connected by a synapse) between CNS and effector organ, innervates smooth muscle and cardiac muscle, glands and GI neurons, can be either excitatory or inhibitory

Question 9

Give brief info regarding differences in preganglionic fibres in sympathetic vs parasympathetic

Answer 9

Sympathetic: exit the spinal chord from the first thoracic (T1) to the second lumbar (L2) levels.
Parasympathetic: exit the brian through cranial nerves and the spinal chord from the second to fouth sacral levels.
Preganglionic neurons of both are controlled by spinal chord and brainstem reflex pathways.