Autonomic nervous system

Question 1

Map of ANS in body

Answer 1

Parasympathetic

• Brainstem
• S2-S4

Sympathetic
- T1-L2

Question 2

Axons of ANS

Answer 2

Always synapse at ganglia [di-synaptic pathway]

- EXCEPT sympathetic supply to adrenal medulla

Question 3

General parasympathetic neuronal pathway

Answer 3

Cranial nerve nuclei/ Grey matter spinal cord—-[myelinated preganglionic axon]—->

Cranial/ spinal nerve—-> Parasympathetic ganglion——[unmyelinated postganglionic axon]—>

Effector organ

Question 4

General sympathetic neuronal pathway

Answer 4

Grey matter spinal cord—[myelinated preganglionic axon, spinal nerve]—–>

Sympathetic ganglion{synapse}—–[unmyelinated postganglionic axon]—–>

Effector organ.

Question 5

Neurotransmission in ANS pathways

• Ganglia
• Postganglion, sympathetic neurones
• Adrenal medulla

Answer 5

In ganglia

• Ach is NT released
• Bind on nicotinic receptors on postganglionic neurones [fast]

Post-ganglionic sympathetic neurones:

• Noradrenaline released [XC in sweatglands, Ach used]
• Binds to adrenergic receptors [slow]

Adrenal medulla:

• Ach released
• Binds to nicotinic receptors on chromaffin cells
• Causes release of adrenaline/noradrenaline into the blood= activation of sympathetic effector organs

Question 6

Alpha-1 adrenergic receptors

Answer 6

G-protein coupled receptor
- Responds to Noradrenaline

Found on blood vessel smooth muscle

Question 7

Beta-1 adrenergic receptors

Answer 7

Found in the heart

G-protein coupled receptor
- Responds to Noradrenaline

Question 8

Beta-2 adrenergic receptors

Answer 8

Found on bronchial smooth muscle cells.

G-protein coupled receptor
- Responds to Noradrenaline

Question 9

Prazosin

Answer 9

Anti-hypertensive —-> Alpha-adrenergic antagonist

Question 10

Atenolol

Answer 10

Anti-hypertensive—-> Beta-adrenergic antagonist

Question 11

Salbutamol

Answer 11

Short acting, beta-2 agonist

- Treatment for asthma

Question 12

Neurotransmission

- Postganglionic parasympathetic neurones

Answer 12

Ach is released

- Binds to muscarinic receptors on effector organs [slow]

Question 13

Atropine

Answer 13

Muscarinic antagonist

Treatment for:

• Bradycardia
• Dilate pupils
• Reduction of glandular secretions

Question 14

White rami communicans

Answer 14

Section of preganglionic fibre that enters the sympathetic trunk
- T1-L2

Question 15

Sympathetic trunk

Answer 15

Interconnected paravertebral ganglia from cervical to sacral levels.

Question 16

Preganglionic fibres entering sympathetic trunk

Answer 16

Either:

1. Synapse in paravertebral ganglion

or
2. Pass through paravertebral ganglio n without synapsing —> form splanchnic nerve and synapse at prevertebral ganglion

Question 17

Route of post-ganglionic fibres from sympathetic trunk

Answer 17

To the periphery:
- Back into spinal nerves via grey rami communicans

To the viscera
- Via medial branches/ plexus

Question 18

Route of post-ganglionic fibres from pre-vertebral ganglia

Answer 18

Postganglionic fibres from sympathetic trunk from plexus around viscera.

Question 19

Cervical sympathetic trunk

Answer 19

3 ganglia

• Superior
• Middle
• Inferior

Satellite- Inferior + T1 ganglia

Question 20

Sympathetic supply to the upper limbs

Answer 20

Post-ganglionic fibres of the cervical ganglia

• Exit via grey rami communicans
• Enters spinal nerves

Question 21

Cervical Sympathetic supply to the heart

Answer 21

Post-ganglionic fibres of cervical sympathetic ganglion

• Travels down common carotid artery to the heart
• Contributes to cardiac plexus

Question 22

Cervical Sympathetic supply to the head

Answer 22

Postganglionic fibres of the superior cervical ganglion

• Travels up the internal —-> Internal carotid plexus
• To eye
• To lacrimal gland
• Travels up external carotid artery—-> External carotid plexus
• To submandibular and parotid glands

Question 23

Pterygopalatine ganglion

Answer 23

Parasympathetic ganglion
- Branch of facial nerve [petrosal nerve] synapses here

• Postganglionic fibres contribute to internal carotid plexus [lacrimal gland and nose mucosa]

Question 24

Horner’s syndrome

Answer 24

Combination of symptoms caused by disruption to sympathetic supply to the head

Any pathway between the hypothalamus to preganglionic neurones is affected
- Descending autonomic pathways [e.g MS]

Symptoms:

• Pupil constriction [miosis]
• Drooping eyelid [ptosis]
• Skin [anhydrosis]

Question 25

Thoracic splanchnic nerves

Answer 25

Preganglionic fibres from thoracic sympathetic nerves. Three nerves: Greater Lesser Least Pierces the diaphragm and synapses in pre-vertebral ganglia: - Celiac - Superior mesenteric - Aorticorenal Post ganglion fibres from pre-vertebral plexus around viscera.

Question 26

Celiac ganglion

Answer 26

Pre-vertebral ganglion where thoracic splanchnic nerve synapses - Supplies stomach + duodenum.

Question 27

Superior mesenteric ganglion

Answer 27

Pre-vertebral ganglion. - Thoracic splanchnic nerves synapses here. Supplies small intestines

Question 28

Aorticorenal ganglion

Answer 28

Pre-vertebral ganglion - Location of synapse for thoracic splanchnic nerves Supplies kidney innervation.

Question 29

Thoracic sympathetic trunk ganglia

Answer 29

12 in total. Post-ganglionic fibres: - Grey rami communicans ---> spinal nerves - Medial branches ---> heart and lungs [cardiac and pulmonary plexus]

Question 30

Lumbar sympathetic trunk - How many - Postganglionic exit - Preganglionic exit

Answer 30

4 ganglia Postganglionic exit: - Grey communicans to spinal nerves Preganglionic exit: - Lumbar splanchnic nerves---> synapse in pre-vertebral ganglia in pelvis - Inferior mesenteric ganglion

Question 31

Inferior mesenteric ganglion

Answer 31

Pre-vertebral ganglion - Lumbar splanchnic nerves [preganglionic fibres] synapse here Supplies large intestine

Question 32

Sacral sympathetic trunk ganglia - How many? - Post-ganglionic exit

Answer 32

4 ganglia in total Post-ganglionic exit: - Grey rami communicans to spinal nerves [supplying lower lim] - Sacral splanchnic nerves to pelvis organs.

Question 33

Parasympathetic preganglionic neurones

Answer 33

Located in: - Brainstem [become cranial nerves] - Grey matter spinal cord [S2-4]---> pelvic splanchnic

Question 34

Location of preganglionic neuronal cell bodies

Answer 34

Cranial nerve nuclei

Question 35

CN 3 nucleus

Answer 35

Edinger-Westphal nucleus

Question 36

CN 7 nucleus

Answer 36

Superior-salivatory nucleus

Question 37

CN 9 nucleus

Answer 37

Inferior salivatory nucleus

Question 38

Vagus nerve nucleus

Answer 38

Nucleus ambiguous Dorsal motor nucleus

Question 39

Ciliary ganglion

Answer 39

Parasympathetic ganglion - Oculomotor nerve synapses here - Innervates sphincter pupillae [pupil constriction]

Question 40

Submandibular ganglion

Answer 40

Parasympathetic ganglion - CN VII synapses here - Innervates submandibular gland = watery saliva

Question 41

Otic ganglion

Answer 41

Parasympathetic ganglion - Glossopharyngeal nerve synapses here. - Innervate parotid gland= watery saliva

Question 42

Sacral parasympathetic innervation - Preganglionic exit - Innervation

Answer 42

Preganglionic fibres exits via pelvic splanchnic nerves Innervates pelvic organs - Forms pelvic plexus - Preganglionic fibres synapse directly onto target organs

Question 43

Sacral parasympathetic function - Bladder - Rectum - Sexual function

Answer 43

Bladder= urination - Contracts bladder wall - Inhibits sphincter Rectum= defecation - Inhibits sphincter Sexual function = vasodilation of erectile tissue

Question 44

Enteric nervous system plexi

Answer 44

Auerbach/ Myenteric plexus = smooth muscle contraction regulation Meissner's/ Submucosal plexus = regulation of glandular secretions