T2 L6 Autonomic nervous system

Question 1

What is the function of the ANS?

Answer 1

Involuntary control
Regulates operation of internal organs
Maintains internal environment
Innervates smooth muscle, cardiac muscle, glands

Question 2

What are the 3 divisions of the ANS?

Answer 2

Sympathetic
Parasympathetic
Enteric

Question 3

What is the function of the sympathetic nervous system?

Answer 3

Fight, flight or fright

Maximise use of metabolic resources

Question 4

What is the function of the parasympathetic nervous system?

Answer 4

Switched on during resting

Increase / conserve metabolic resources

Question 5

Where is parasympathetic located?

Answer 5

Brainstem

S2-S4

Question 6

Where is sympathetic located?

Answer 6

T1 to L2

Question 7

What happens when acetylcholine binds to nicotinic receptors on postganglionic neurons?

Answer 7

Ionotropic ligand gated (fast)
Acetylcholine opens pore
Influx of calcium & sodium leading to depolarisation

Question 8

What is the main neurotransmitter in the sympathetic postganglionic neurons?

Answer 8

Noradrenaline

Except for sweat glands which use acetylcholine

Question 9

What are the 3 adrenergic subtypes?

Answer 9

Alpha 1
Beta 1
Beta 2

Question 10

Where is alpha 1 found?

Answer 10

Smooth muscle of blood vessel

Prazosin is an alpha 1 antagonist used to treat hypertension

Question 11

Where is beta 1 found?

Answer 11

On the heart

Atenolol is B1 antagonist used to treat hypertension

Question 12

Where is beta 2 found?

Answer 12

On smooth muscle in bronchial

Salbutamol is beta 2 agonist used to treat asthma

Question 13

Describe the sympathetic neurons within adrenal medulla

Answer 13

Acetylcholine is main neurotransmitter

Binds to nicotinic receptors on chromatin cells leading to release of adrenaline / NA into circulation

Question 14

Describe postganglionic parasympathetic neurons

Answer 14

Acetylcholine is main neurotransmitter
Binds to muscarinic receptors on effector organ
Metabotropic G-protein coupled (slow)

Question 15

What is atropine?

Answer 15

Cholinergic muscarinic antagonist which lowers parasympathetic activity
Treat bradycardia, dilate pupils, reduce glandular secretions

Question 16

Describe the effects of the sympathetic system

Answer 16

Larger system
Cardiac muscle –> increases pacemaker activity & contractile force
Bronchi of lungs –> bronchodilator
Sweat glands –> sweat secretion
Hair follicles –> piloerection
Blood vessels –> vasoconstriction in skin, vasodilation in skeletal muscle
Abdomino-pelvic viscera –> inhibit peristalsis & gastric secretions. Stimulates glucagon secretion. Stimulates adrenaline secretion from adrenal medulla
Eye –> dilates pupils

Question 17

What is the sympathetic trunk?

Answer 17

Interconnected paravertebral ganglion
Extends from cervical to sacral levels
Preganglionic fibres enter sympathetic trunk through white rami communications (from T1-L2 spinal nerves only)

Question 18

What happens to preganglionic fibres once they have entered sympathetic trunk?

Answer 18

Synapse in ganglia at same level or travel to another level
OR
Pass through ganglion into splanchnic nerves to synapse in prevertebral ganglion

Question 19

Describe postganglionic sympathetic fibres

Answer 19

More numerous than preganglionic
From sympathetic trunk they go to periphery or visceral
From the pre vertebral ganglion they form plexus around viscera

Question 20

Describe the path of postganglionic sympathetic fibres to the periphery

Answer 20

Via grey rami communicans back into spinal nerves

Sweat glands, hair follicles, blood vessels

Question 21

Describe the path of postganglionic sympathetic fibres to the viscera

Answer 21

Via medial branches / plexus

Heart, lungs, head

Question 22

What are the 3 ganglia in the sympathetic trunk?

Answer 22

Superior ganglia
Middle ganglia
Inferior ganglia

Question 23

What happens to the inferior cervical ganglia in sympathetic trunk?

Answer 23

Fuses with T1 to form stellate ganglion

Question 24

Describe the exit of postganglionic fibres from the cervical sympathetic trunk

Answer 24

Exit via grey rami communicans to spinal nerves for sympathetic supply to upper limbs
Piggy back down common carotid to heart
Piggy back up internal / external carotid artery to head

Question 25

What does the sympathetic internal carotid plexus do?

Answer 25

To eye to dilate pupil, smooth muscle of eyelid

To lacrimal gland to inhibit secretion

Question 26

What does sympathetic external carotid plexus do?

Answer 26

To submandibular & parotid glands to inhibit secretions

Question 27

What is horner’s syndrome?

Answer 27

Disruption of sympathetic supply t head
Any part of pathway
Pupil --> mitosis
Eyelid --> ptosis
Skin of face --> anhidrosis

Question 28

Describe thoracic sympathetic

Answer 28

12 thoracic sympathetic trunk ganglia
Postganglionic fibres exit via: grey rami communicans to spinal nerves & medial branches to heart and lungs
Preganglionic fibres exit via: thoracic splanchnic nerves to abdomen to prevertebral ganglia

Question 29

Describe thoracic splanchnic nerves

Answer 29

Pierce diaphragm
Synapse in pre vertebral ganglia
Ganglia located close to abdominal aorta
Postganglionic fibres form pre vertebral plexus around viscera

Question 30

Were does celiac ganglion innervated?

Answer 30

Stomach / duodenum

Question 31

Where does superior mesenteric ganglion innervate?

Answer 31

Small intestine

Question 32

Where does aorticorenal ganglion innervate?

Answer 32

Kidney

Question 33

Describe lumbar sympathetic

Answer 33

4 lumbar sympathetic trunk ganglia
Postganglionic fibres exit via grey rami communicans to spinal nerves
Preganglionic fibres exit via lumbar splanchnic nerves to perlves
Inferior mesenteric ganglia goes to large intestine

Question 34

Describe sacral sympathetic

Answer 34

4 sacral sympathetic trunk ganglia

Postganglionic fibres exit via grey rami communicans to spinal nerves or sacral splanchnic nerves to pelvic organs

Question 35

Describe parasympathetic system

Answer 35

Smaller division
Cardiac muscle –> decreases pacemaker activity & contractile force
Bronchi of lungs –> bronchoconstriction
Sweat glands –> none
Hair follicles –> none
Blood vessels –> none except male erectile tissue / salivary glands which dilate
Abdomino-pelvic viscera –> stimulates peristalsis & gastric secretions
Eye –> constricts pupil
Salivary & lacrimal glands –> secretion of watery saliva & tears

Question 36

Where are preganglionic parasympathetic fibres found?

Answer 36

Within brainstem –> cranial nerves –> head, heart, lungs, abdomen
Grey matter spinal cord –> pelvic splanchnic nerves –> pelvic organs
All ganglia located close to target organ

Question 37

Describe cranial parasympathetic

Answer 37

Preganglionic axons pass through cranial nerves to ganglia
Oculomotor nerve –> sphincter pupillae (constriction)
Facial nerve –> lacrimal gland (tears) & submandibular gland (water saliva)
Vagus nerve to heart, lungs, abdominal viscera

Question 38

Describe sacral parasympathetic

Answer 38

From sacral spinal cord
Preganglionic fibres exit via pelvic splanchnic nerves tp pelvis organs
Form pelvic plexus over viscera

Question 39

What is the function of sacral parasympathetic?

Answer 39

Bladder (urination): contraction of bladder wall, inhibition of bladder sphincter
Rectum (defecation): inhibition of rectal sphincter
Sexual function: vasodilation in erectile tissue

Question 40

Describe the 2 plexi of the enteric nervous system

Answer 40

Auerbach’s - regulate muscle contraction
Meissners - regulate glandular secretion
Contains 10-100 billion neurons
Retains function after all central connections are severed