Structure of the Autonomic Nervous System Flashcards
(33 cards)
Autonomic Nervous System
Parts of the Nervous System under Involuntary control
Examples of autonomic functions
Secretion of saliva
Heart Function
Eye focus
Pupillary dilation
Which muscles are controlled by the Somatic NS and ANS
SNS - Skeletal
ANS - Smooth and Cardiac muscle
Divisions of ANS
Sympathetic - Involved in stress (fight or flight)
Thought of as an accelerator
Parasympathetic - Rest, growth, maintenance (Rest and Digest)
Thought of as ‘break’
Biological responses to fight or flight sympathetic NS response
Positive cardiac inotropy and chronotropy
Vasoconstriction in gut
Vasodilation in SkM
Increased sensory awareness
Sweat secretion
**Also I think bronchodilatation
Compare the neurons of the somatic nervous system and the autonomic nervous system
Compare the neurons of the sympathetic and parasympathetic nervous systems
Paravertebral Column
Nerves innervating the area between T1 and L3 of the spine
Area of nerves above the T1 vertebra
Pre-vertebral column
Where do pre-ganglionic fibres of the sympathetic NS emerge from in the spinal cord
T1-L2
note that they innervate paravertebral or prevertebral ganglia
Describe the structure of the paravertebral chain relative to each vertebra
Direct association with the specific ganglia and the spinal cord at each spinal segment
Compare the Somatic NS to the Sympathetic (structure)
Afferent nerve passes through dorsal horn before entering the spinal column
In intermediolateral column, there are cell bodies of pre-ganglionic fibres which leave the cord via the ventral horn; they synapse with the sympathetic ganglia in the paravertebral column with a post-ganglionic fibre which leaves and the efferent nerve then controls its target tissue
**The pre-ganglionic fibre synapses with more than one post-ganglionic fibre in another spinal segment (could be at next segment down/up or further)
How does the sympathetic outflow from the spinal cord work
The efferent nerve leaves via the ventral horn; it reaches the para-vertebral horn via the white ramus (myelinated) where it synapses with the post-ganglionic fibre
The post ganglionic fibre leaves via the grey ramus (unmyelinated) where it then goes to the target tissue
Alternatively, the post ganglionic fibre moves up the para-vertebral chain
How is the eye innervated via the sympathetic nervous system
The preganglionic NS synapses with the post-ganglionic fibre at another part of the paravertebral column
Midline plexus
Paravertebral chain is on either side of the spinal column - each pre-ganglionic fibre moves down para-vertebral chain, exits down and synapses with post ganglionic fibres at the splanchnic nerves
Cranio-Sacral outflow
Exits of the parasympathetic NS from the spine - From the top of the spinal cord or the base of the spinal cord
Functions of 3rd, 7th, 9th and 10th Cranial Nerves
III: Oculomotor (Eye)
VII: Facial (Lacrimal and salivary Glands)
IX: Glossopharyngeal (same as VII)
X: Vagus (Heart, Lungs, Upper GI Tract)
What tissue do Sacral Parasympathetic nerves control
Lower GI Tract
Bladder
Genitalia
Which neurotransmitters are used by Sympathetic Nerves
ACh in pre
Noradrenaline/Adrenalin in post
nACh-R in pre-post synapse
α or β adrenoceptor in neuromuscular junction
Which neurotransmitters are used by Parasympathetic Nerves
ACh in pre and post
nACh-R in pre-post synapse
mACh-R in NMJ
Not ionotrotropic receptors - metabotropic/G-protein coupled receptors
Exceptions to ANS Neurotransmission
ACh acts on metabotropic ACh receptor in sympathetic NS and Post NT is ACh
Tissues with only sympathetic Innervation
Adrenal Medulla Pilorector muscles (hair follicles) Sweat Glands Spleen Many Blood vessels (especially in skin)
Tissues with only parasympathetic Innervation
Ciliary muscle (eye) Constrictor pupillae (eye)
Autonomic innervation of the eye
Controls the pupillary size and shape of the lens
