Autonomic Nervous System

Question 1

Describe how the Nervous system is divided up

Answer 1

Peripheral divided into:
Autonomic (sympathetic vs parasympathetic) vs Somatic (sensory input vs motor output)
Central (brian vs spinal cord)

Question 2

What does the autonomic nervous sytem control?

Answer 2

Stress response, digestion, micturition, cardiovascular control, temperature, sex and reproduction

Question 3

How are the sympathetic and parasypathetic nervous systems similar?

Answer 3

Both have synapses in ganglion, sensory and effector effect, use acetylcholine in ganglion transmission

Question 4

What major effect does the sympathetic nervous system have?

Answer 4

• Pupils dilate
• Dry mouth
• Nasal decongestion
• Adrenal glands release adrenaline (increase heart rate, more powerful contraction, vasodilation to skeletal musle and skin)
• Constipation: reduced blood supply to GI
• Urinary and fluid retention
• Renal: vasoconstriction
• Sweat increased

Question 5

What is the anatomical location of the sympathetic nervous system?

Answer 5

Origins: thoracolumbar (T1 - L2/3) apart from cervical ganglia
Ganglia: next to spine, pre-ganglionic neurone very short

Question 6

What neurotransmitters and receptor are used in the sympathetic nervous system?

Answer 6

Neurotransmitters:
- Preganglionic: acetylcholine
- Postganglionic: noradrenaline (apart from sweat glands and deep muscle vessels use acetylcholine)

Receptors:
Alpha-receptors
- Alpha 1 (peripheral) - arteriole constriction, caused increased blood pressure returning to heart
- Alpha 2: mainly in heart, coronary and venous vasoconstriction
Beta-receptors:
- Beta 1: heart (increases heart rate and contractility)
- Beta 2: smooth muscle relaxation (lungs, uterus, gut, bladder, eye, skeletal muscle blood vessels)

Question 7

What major effect does the parasympathetic nervous system have?

Answer 7

• Pupillary constriction
• Nasal engorgement
• Increased salivations
• Increased gastric secretions and blood flow
• Slows down heart rate
• Bronchodilation
• Micturate, defecate and ejactulate
• Sexual arousal

Question 8

What is the anatomical location of the parasympathetic nervous system?

Answer 8

Origin: craniosacral outflow cranial nerves 3,7,9,10, sacral S2,3,4 (innervates GI tract and sexual organs)

Ganglia: near site of action, diffuse gangli in vagus (cervical plexus, thoracic plexus, coeliac plexus)

Question 9

What neurotransmitter is used in the parasympathetic nervous system?
List the receptors involved and their location:

Answer 9

Neurotransmitters: uses acteylcholine in pre and post glanglionic synapses

Receptors:
Muscarinic receptors:
- M2: slows heart rate
- M3: salivary glands, gut, bladder, blood vessels and eye
- M1, 4, 5: brian
Nicotinic receptors:
- N1: stimulates motor neurones causing contraction
- N2: autonomic nervous system

Question 10

What are the 3 main roles of the central part of the autonomic nervous system?

Question 11

What causes brian death?
What does brain stem death result in?

Answer 11

Cause:
- Coning: raised pressure on brainstem due to swelling of cerebrum
- Damage to single blood vessel supplying brainstem
Result:
- Paralysis and unconsiousness
- Apnoea: no breathing
- Loss of cranial nerve function
- Dilated/ blown pupil (1 or both)

Question 12

What are the principles of brain stem death testing?

Answer 12

• Known irreversible cortical death
• Exclusion criteria met
• Unconsciousness and apnoea
• Testing cranial nerve function

Question 13

Why is pharmacology important and what effect does it have on autonomic nervous system?

Answer 13

Autonomic dysfunction can result in myriad of symptoms as it has such a wide ranging innervation