Autonomic Nervous System Flashcards
What is a collection of cell bodies known as?
Ganglia
In the sympathetic system, what runs alongside the spinal cord?
Sympathetic trunk
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
What are the five ganglia of the SS?
Cervical ganglion (Superior, middle & Inferior)
Celiac ganglion
Superior mesenteric ganglion
Aortico-renal ganglion
Inferior mesenteric ganglion
What is the plexus of the SS?
Hypogastric plexus
Most of the SS is di-synaptic but what is the exception?
Adrenal medulla - needs fast innervation so direct innervation
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).
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.
What are the ganglia of the PSS?
Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion
In the SS - what does the celiac ganglion innervate?
Liver, stomach & pancreas
In the SS - what does the superior mesenteric ganglion innervate?
Intestines
In the SS - what does the aortic-renal ganglion innervate?
Adrenal medulla & kidney
In the SS - what does the inferior mesenteric ganglion innervate?
Colon, anal sphincter, ureter & bladder
In the SS - what does the hypogastric plexus innervate?
Genitalia & bladder
Where do SS fibres arise from
Spinal cord levels T1-L2
Where do PSS fibres arise from?
Brainstem - CN III, VII, IX & X
Sacral region - S2-4
In the PSS - what des the ciliary ganglion innervate & via which cranial nerve?
Eye - CN III
In the PSS - what dos the pterygopalatine ganglion innervate and via which CN?
Lacrimal & nasal glands - CN VII
In the PSS - what dos the submandibular ganglion innervate & via which CN?
Submandibular & sublingual glands - CN VII
In the PSS - what does the otic ganglion innervate and via which CN?
Parotid gland - CN IX
In the PSS - What does the vagus nerve innervate?
Heart
Stomach (inc pylorus)
Colon
Small intestine
In the PSS - what do S2-4 innervate?
Anal sphincter, part of colon, genitalia & bladder
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.
What are the three divisions of the ANS?
Sympathetic
Parasympathetic
Enteric
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
