Autonomic nervous system

Question 1

What is the autonomic nervous system used for?

Answer 1

Involuntary control:

• Regulates operation of the internal organs
• Maintains internal environment
• Innervates smooth muscle, cardiac muscle, glands

Question 2

Describe the sympathetic system

Answer 2

Fight, flight, fright

Maximises use of metabolic resources

Question 3

Describe the parasympathetic system

Answer 3

Opposite to sympathetic division

Switched on during resting

Increases/conserves metabolic resources

Question 4

Which divisions work to control the internal environment?

Answer 4

Both sympathetic and parasympathetic

Question 5

Where is the parasympathetic function found?

Answer 5

Brainstem

S2 to S4 of spinal cord

Question 6

Where is the sympathetic division found?

Answer 6

T1 to L2 spinal cord

Question 7

Describe the axons of the autonomic nervous system

Answer 7

Do not pass directly to effector organs
Form disynaptic pathways
Myelinated Ganglia unmyelinated effector organ

Question 8

Within autonomic ganglia which is the main neurotransmitter?

Answer 8

Acetylcholine

Question 9

Where does acetylcholine bind?

Answer 9

Nicotinic receptors on postganglionic neurons

Ionotropic ligand gated (fast influx of Ca2+ and Na+ causing depolarisation)

Question 10

Within postganglionic sympathetic neurons which is the main neurotransmitter?

Answer 10

Noradrenaline

Question 11

Where does noradrenaline bind?

Answer 11

Adrenergic receptors on effector organ

Metabotropic G protein coupled

Question 12

What is prazosin?

Answer 12

Alpha 1 antagonist used in hypertension

Question 13

What is atenolol?

Answer 13

Beta 1 antagonist used in hypertension

Question 14

What is salbutamol?

Answer 14

Beta 2 agonist used in asthma

Question 15

Within the adrenal medulla which neurotransmitter is present?

Answer 15

Acetylcholine

Question 16

Where does acetylcholine bind in adrenal medulla?

Answer 16

Nicotinic receptors on chromaffin cells
Causes release of adrenalin/noradrenalin
Direct activation of sympathetic organs

Question 17

Which neurotransmitter is used in postganglionic parasympathetic neurons?

Answer 17

Acetylcholine

Question 18

What is atropine?

Answer 18

cholinergic-muscarinic antagonist (Lowers parasympathetic activity)
Used to treat bradycardia, dilate pupils, reduce glandular secretions

Question 19

Which parts of the body use the sympathetic system?

Answer 19

Cardiac muscle

Bronchi of lungs

Sweat glands

Hair follicles

Blood vessels

Abdomino-pelvic viscera

Eye

Question 20

Describe the sympathetic trunk/chain

Answer 20

Interconnected paravertebral ganglia

Extends from cervical to sacral levels

Question 21

Where do preganglionic fibres enter the sympathetic trunk?

Answer 21

Preganglionic fibres enter sympathetic trunk through white rami communicans

Question 22

On entering the trunk, preganglionic fibres either:

Answer 22

Synapse in ganglion (same level or travel to another level)

Pass through ganglion in splanchnic nerves to synapse in prevertebral ganglia

Question 23

From sympathetic trunk, postganglionic fibres follow one of two routes:

Answer 23

To the periphery (sweat glands, hair follicles, blood vessels)
- Via grey rami communicans back into spinal nerves

To the viscera (heart, lungs, head)
- Via medial branches/plexus

Question 24

From prevertebral ganglia, postganglionic fibres form

Answer 24

plexus around viscera

Question 25

Describe the cervical sympathetic

Answer 25

3 ganglia in cervical sympathetic trunk - Superior/middle/inferior cervical ganglia [Stellate ganglion = fused inferior cervical and T1 ganglia]

Question 26

Where do the postganglionic fibres exit?

Answer 26

Via gray rami communicans to spinal nerves (sympathetic supply to upper limbs) Piggy back down common carotid artery to the heart (sympathetic supply to the heart) “Piggy back” up internal/external carotid artery to head (internal carotid plexus - to eye (dilates pupil,smooth muscle of eyelid and to lacrimal gland (inhibits secretions) or external carotid plexus (to submandibular and parotid plexus (inhibits secretions))

Question 27

What is horner's syndrome?

Answer 27

Disruption of the sympathetic supply to head Any part of pathway - hypothalamus to preganglionic neurons E.g. Lesions within brainstem/cervical spinal cord (in MS or apical lung tumours) (Affecting descending autonomic regulatory pathways) Affecting pupil (Miosis - constriction of pupil), eyelid (Ptosis - drooping of eyelid) or skin to the face (Anhidrosis - lack of sweating)

Question 28

Describe the thoracic sympathetic

Answer 28

12 thoracic sympathetic trunk ganglia

Question 29

Postganglionic fibres exit via:

Answer 29

Grey rami communicans to spinal nerves Medial branches to heart and lungs

Question 30

Preganglionic fibres exit via:

Answer 30

Thoracic splanchnic nerves to abdomen | Greater, lesser and least to prevertebral ganglia

Question 31

Where do the thoracic splanchnic nerves synapse?

Answer 31

``` In prevertebral ganglia Celiac ganglion - Stomach/duodenum Superior mesenteric ganglion - Small intestine Aorticorenal ganglion - Kidney ```

Question 32

Where are the ganglia located?

Answer 32

Close to abdominal aorta

Question 33

Describe the lumbar sympathetic

Answer 33

4 lumbar sympathetic trunk ganglia

Question 34

Where do postganglionc fibres of the lumbar sympathetic exit?

Answer 34

Via Grey rami communicans to spinal nerves

Question 35

Where do preganglionic fibres of lumbar sympathetic exit?

Answer 35

Lumbar splanchnic nerves to pelvis

Question 36

Describe the sacral sympathetic

Answer 36

4 sacral sympathetic trunk ganglia

Question 37

Where do Postganglionic fibres of the sacral sympathetic exit?

Answer 37

Grey rami communicans to spinal nerves (lower limb) Sacral splanchnic nerves to pelvic organs

Question 38

Describe the parasympathetic system

Answer 38

Smaller division Cardiac muscle - decreases pacemaker activity and contractile force Bronchi of lungs - bronchoconstriction Sweat glands - None Hair follicles - None Blood vessels - None Abdominopelvic viscera - stimulates peristalsis and release of gastric secretions Eye - constrict Salivary and lacrimal glands - Increase secretions

Question 39

Describe the parasympathetic preganglionic fibres

Answer 39

Preganglionic neurons within: Brainstem Grey matter spinal cord (part that forms S2 – S4 spinal nerves) All ganglia located close to target organ

Question 40

Describe the cranial parasympathetic neuronal cell bodies

Answer 40

Preganglionic neuronal cell bodies in cranial nerve nuclei | Cranial nerve 3, 7, 9 and 10

Question 41

Describe the cranial parasympathetic preganglionic axons

Answer 41

Preganglionic axons pass through cranial nerves to ganglia Cranial nerve 3 (to ciliary ganglion), 7 (to pterygopalatine ganglion and submandibular ganglion) and 9 (to otic ganglion)

Question 42

Where does the vagus nerve pass to?

Answer 42

Heart Lungs Abdomen

Question 43

Describe the sacral parasympathetic system

Answer 43

From sacral spinal cord Preganglionic fibres exit via: Pelvic splanchnic nerves to pelvic organs Form pelvic plexus over viscera Preganglionic fibres synapse in walls of target organs

Question 44

List the functions of the sacral parasympathetic division

Answer 44

Bladder (urination) Contraction of bladder wall Inhibition to bladder sphincter Rectum (defecation) Inhibition of rectal sphincter Sexual function Vasodilation in erectile tissues

Question 45

Describe the enteric nervous system

Answer 45

In walls of gastrointestinal tract 2 very complicated plexi: Auerbach’s – Regulates muscle contraction - between muscle wall Meissner’s – Regulates glandular secretions - On inside wall Contains 10-100 billion neurons Very unusual – retains functions after all central connections severed Truly autonomic