Autonomic Nervous System Flashcards by Hannah Wilkinson

What is a collection of cell bodies known as?

Ganglia

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In the sympathetic system, what runs alongside the spinal cord?

Sympathetic trunk

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What is the purpose of the sympathetic trunk?

Nerves enter from the spinal cord and can either pass directly through (Splanchnic nerves) or they can ascend or descend and synapse at different levels to innervate structures at different levels to where they exited the spinal column

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What are the five ganglia of the SS?

Cervical ganglion (Superior, middle & Inferior)
Celiac ganglion
Superior mesenteric ganglion
Aortico-renal ganglion
Inferior mesenteric ganglion

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What is the plexus of the SS?

Hypogastric plexus

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Most of the SS is di-synaptic but what is the exception?

Adrenal medulla - needs fast innervation so direct innervation

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Are pre-ganglionic neurons long or short in the SS? Why?

Short (compared to PSS) - because they synapse in the ganglia near to the spinal cord (centrally located).

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Are pre-ganglionic neurons long or short in the PSS? Why?

Long - because they synapse very close (or in the wall of) their effector organ.

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What are the ganglia of the PSS?

Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion

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In the SS - what does the celiac ganglion innervate?

Liver, stomach & pancreas

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In the SS - what does the superior mesenteric ganglion innervate?

Intestines

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In the SS - what does the aortic-renal ganglion innervate?

Adrenal medulla & kidney

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In the SS - what does the inferior mesenteric ganglion innervate?

Colon, anal sphincter, ureter & bladder

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In the SS - what does the hypogastric plexus innervate?

Genitalia & bladder

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Where do SS fibres arise from

Spinal cord levels T1-L2

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Where do PSS fibres arise from?

Brainstem - CN III, VII, IX & X
Sacral region - S2-4

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In the PSS - what des the ciliary ganglion innervate & via which cranial nerve?

Eye - CN III

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In the PSS - what dos the pterygopalatine ganglion innervate and via which CN?

Lacrimal & nasal glands - CN VII

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In the PSS - what dos the submandibular ganglion innervate & via which CN?

Submandibular & sublingual glands - CN VII

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In the PSS - what does the otic ganglion innervate and via which CN?

Parotid gland - CN IX

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In the PSS - What does the vagus nerve innervate?

Heart
Stomach (inc pylorus)
Colon
Small intestine

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In the PSS - what do S2-4 innervate?

Anal sphincter, part of colon, genitalia & bladder

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Why is it important that the ANS responds rapidly?

Because it is part of our fight or flight response - need to be able to get away when we sense danger.

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What are the three divisions of the ANS?

Sympathetic
Parasympathetic
Enteric

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Is the ANS part of the central nervous system or the peripheral nervous system?

Peripheral

Apart from the ANS, what is one other major component of the PNS?

Somatic nervous system

Does sympathetic system maximise use or conserve use of metabolic resources?

Maximises use

Does the PSS maximise use or conserve use of metabolic resources?

Conserves metabolic resources

Which system does SLUDD apply to - and what does it stand for?

PSS Salivation Lacrimation Urination Defecation Digestion

Which part of the spinal cord is involved with SS?

T1 to L2

Are preganglionic axons myelinated or non-myelinated?

Myelinated - therefore WM

Are postganglionic axons myelinated or unmyelinated?

Unmyelinated - therefore GM

In pre-synaptic neurons in the ANS - what is the main NT they release?

Acetylcholine (ACh)

What type of receptors are present on post-ganglionic neurons? What does this mean for transmission?

Nicotinic Opened by ACh They are ionotropic (Ligand-gated) - therefore fast transmission

What is the main NT released by post-ganglionic SYMPATHETIC neurons?

Noradernaline

What is the exception to the post-ganglionic SYMPATHETIC neuron using NOR rule? What do they use instead?

Sweat glands - instead use ACh

What receptors are present on effector organs (that receive stimulus from post-ganglionic SYMPATHETIC neuron)?

Metabotropic - G-protein coupled = slower

What are four types of g-protein receptor found in the sympathetic division?

α-1 (Gq) - constrict BV α-2 β-1 - heart (inc HR) β-2 - lungs (dilate airways)

What are three types of receptor found in the parasympathetic division? What type are they?

Muscarinic receptors M1 M2 M3

How does neurotransmission work in the adrenal medulla?

Just one neuron - so ACh is released which binds to nicotinic receptors on chromaffin cells in adrenal medulla. This causes direct release of ADR (80%) and NOR (20%) into circulation.

Post-ganglionic neurons in the PARASYMPATHETIC system are activated by which NT?

ACh

Which NT is released by post-ganglionic neurons in the PSS? What type of receptor does this affect in the target organ?

Release ACh Muscarinic (G-protein coupled) receptors

What are muscarinic (cholinerghic) antagonists used to treat? Give an example of one such drug.

Atropine Treat bradycardia, reduce glandular secretions & dilate pupils

Which is faster - SS or PSS?

SS - requires a quick response than PSS.

What is the sympathetic trunk?

Interconnected paravertebral ganglia extending from cervical to sacral levels.

How to pre-ganglionic fibres enter the sympathetic trunk?

Through white rami communicantes

In which part of the spinal cord are the SS preganglionic cell bodies found?

Lateral horn

The SS preganglionic nerves can synapse in the sympathetic trunk. From which structure do the SS post-ganglionic fibres then exit?

The grey ramus communicans

When SS preganglionic fibres enter the sympathetic trunk - what do they do?

(1) Synapse in the ganglion - either at the same level or by ascending/descending to another level OR (2) Pass straight through as splanchnic nerves

Where do splanchnic nerves synapse?

In prevertebral ganglia (closer to target organs)

Describe the path of a SS nerve fibre.

Starts in lateral horn, exits via ventral root, travels via white rami communicans and enters the sympathetic trunk. Here it can synapse, or ascend/descend to synapse at different levels. Alternatively can pass straight through = splanchnic nerve - and synapse instead in the prevertebral ganglion, normally forming a plexus around the viscera. If it synapses in the sympathetic trunk - it then exits as a post-ganglionic nerve - can then travel to periphery (via grey ramus communicans and spinal nerve) or to the viscera (via medial plexus).

What are the two routes for postganglionic fibres exiting the sympathetic trunk

Travel to periphery (via grey rami communicans and spinal nerves) Travel to viscera (heart, lungs, head) - via medial plexus

Which ganglia supply sympathetic innervation to the head, upper limbs & heart

Cervical ganglia

What are the names of the three cervical sympathetic ganglia?

Superior Middle Inferior

What do cervical sympathetic fibres travel down to reach the heart?

The common carotid artery

What do cervical sympathetic fibres travel up to reach the head?

Internal & external carotid arteries - forms internal carotid plexus and external carotid plexus

What does the internal carotid plexus do?

Provides SS to eye & lacrimal gland - dilates pupil - raises eye lid - inhibits lacrimal gland secretions (tears)

What does the external carotid plexus do?

Provide SS innervation to the submandibular and parotid glands - this inhibits production of saliva.

What do SS thoracic ganglia supply?

Heart, lungs and abdominal viscera.

How do the SS postganglionic fibres innervate the (a) periphery and (b) viscera of the thorax?

Periphery = exit sympathetic trunk via grey rami communicantes and join spinal nerves to innervate. Viscera - for medial plexi around the heart and lungs = pulmonary plexus & cardiac plexus Splanchnic nerves also form a plexus around viscera

What are the names of the two plexi in the thoracic sympathetic division?

Pulmonary plexus Cardiac plexus

What is the combined name for the plexi in the thoracic sympathetic system?

Cardiac-pulmonary plexus

What do lumbar ganglia supply?

Abdominal viscera & lower limb

What are the two ways that lumbar ganglia provide SS innervation to the abdomen & lower limb?

Postganglionic fibres exit the sympathetic trunk via grey rami commuicantes to spinal nerves - then innervate. OR Preganglionic fibres pass through the sympathetic chain without synapsing = LUMBAR SPLANCHNIC NERVES. These then synapse in prevertebral ganglia and can form a plexus around organs.

What do sacral ganglia provide sympathetic innervation to?

Pelvis & Lower Limb

What are the two ways that sacral ganglia supply the pelvis and lower limb with sympathetic innervation?

Either exit the sympathetic trunk via grey rami communicantes to join spinal nerves to the lower limb OR Pass directly through the sympathetic trunk as SACRAL SPLANCHNIC NERVES and synapse in prevertebral ganglia close to pelvic organs. Can form localised plexi near organs.

Why does the PSS not require the same level of branching as the SS?

PSS doesnt have the same requirements for speed - doesnt need to innervate multiple structures simultaneously = less branching.

Which is the major cranial nerve involved in the PSS?

Vagus nerve - innervates about 75% of the PSS.

Which vertebral levels do PSS preganglionic fibres arise from?

Brainstem (CNs 3, 7 9 & 10) S2-S4

Where are PSS ganglia located?

Close to (or in the wall of) the target organ

Where are cranial preganglionic neuronal cell bodies found?

Within cranial nerve nuclei.

Where is the cranial nerve nuclei for the following found? - CN III - CN VII - CN IX - CN X

III = Midbrain VII = Pons IX & X = Medulla

What is the name of the nucleus for CN III?

Edinger-Westphal nucleus

What is the name of the nucleus for CN VII?

Superior salivatory nucleus

What is the name of the nucleus for CN IX?

Inferior salivatory nucleus

What is the name of the nucleus for the vagus nerve?

Nucleus ambiguous & Dorsal motor nucleus

What is the name of the ganglion where SS fibres synapse in CN III?

Ciliary ganglion

What does CN III control the PSS of?

Eye (pupil constriction) & movement (ciliary muscle)

What is the name of the ganglion where SS fibres synapse in CN VII?

Pterygopalatine ganglion (lacrimal & nasal glands) Submandibular ganglion (submandibular and sublingual glands)

What is the name of the ganglion where SS fibres synapse in CN IX?

Otic ganglion (parotid gland -saliva)

Through what opening does CN X exit the cranium?

Jugular foramen

What does CN X innervate?

Lungs, heart & abdominal organs

What doe the sacral spinal cord fibres provide PSS innervation to?

Bladder (urination - contract wall & relax sphincter) Rectum (relax sphincter) Sexual function = vasodilation

What do preganglionic PSS fibres exit the spinal cord as?

Pelvic splachnic nerves

What is the name of the plexus formed by the sacral PSS fibres?

Inferior hypogastric plexus

Where do sacral preganglionic fibres of the PSS synapse?

In walls of target organs

What are the two plexi of the enteric nervous system and what do they control?

Myenteric = motility / contraction - found in muscular layer Submucosal = glandular secretions & blood flow - found in submucosal layer

Does the enteric system function in conjunction with or independently or the CNS?

Independently of the CNS.

Which nerves innervate the enteric nervous system

Vagus nerve & splanchnic nerves

Autonomic Nervous System Flashcards

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