6.3 Neuro Anatomy & Physiology - The Autonomic Nervous System Flashcards
What are four organs that the sympathetic nervous system controls that the parasympathetic does not?
- Arrector pili
- Sweat glands
- Skin blood vessels
- Skeletal blood vessels
Which of the somatic/autonomic nervous system is voluntary vs involuntary?
Somatic: Voluntary
Involuntary: Autonomic
What are the names of the two neurons in the 2-neuron chains of the autonomic nervous system?
- Pre-ganglionic
- Post-Ganglionic
Where do pre-ganglionic cell bodies originate?
Brain or spinal cord
Where do post-ganglionic neurons originate?
Outside the CNS
How many neurons in a typical somatic nervous system efferent pathway?
One
Which neurotransmitter does the pre-ganglionic neuron always use to communicate with the post-ganglionic neuron?
Acetylcholine
What neurotransmitter is most commonly used in the post-ganglionic neurons of the sympathetic nervous system? What are the exceptions?
Noradrenaline is most common.
Ach is used for sweat glands
Adrenaline is used when innvervating the adrenal medulla
What neurotransmitter does the parasympathetic nervous system exclusively use?
Ach
What structures does the sympathetic nervous system innervate?
- Visceral organs
- Adrenal gland
- Vascular smooth muscle
- Sweat glands
- Arrector pili
What structures does the parasympathetic nervous system innervate?
Visceral organs (head, neck, trunk, genitalia)
What responses to alpha-1 and alpha-2 receptors have?
Smooth muscle contraction
What response to beta-1 receptors have?
Cardiac muscle contraction
What response to beta-2 and beta-3 receptors have?
Smooth muscle relaxation
Are the pre/post–ganglionic fibres of the sympathetic nervous system long or short?
Short pre, and long post
In which sections of the spine can neuronal cell bodies from sympathetic pre-ganglionic neurons be found?
Thoracic and lumbar
Where do fibres of the lateral horn leave the spinal cord?
Ventral root
Which type of sympathetic ganglia are paired and which are single
Paravertebral: Paired
Prevertebral: Single
What do paravertebral ganglions supply?
- Vascular smooth muscle
- Arrector pili
- Visceral organs of the head, neck, and thorax
- Many other things
What do prevertebral ganglions supply?
Visceral organs of abdomen and pelvis
Draw a diagram of the paravertebral membranes attaching to the spinal cord and spinal nerves
How does the sympathetic chain increase the versatility of pre-ganglionic neurons?
These neurons can relay messages up or down the sympathetic chain, which spans the entire spinal cord, allowing for the message to be delivered to a greater number of places
What are the two fates of a sympathetic pre-ganglionic neuron that innervates paravertebral ganglia?
After innervating paravertebral ganglia:
1. Innervates spinal nerve (skeletal muscle)
2. Innervates splanchnic nerve (visceral targets)
What do prevertebral ganglia innervate? With what nerves?
Internal organs of pelvis and abdomen. This occurs via splanchnic nerves
What hormones are released by the adrenal medulla when it is directly innervated by a pre-ganglionic sympathetic fibre? Why is this significant?
- Noradrenaline (20%), adrenaline (80%)
- This is significant because noradrenaline is the primary messenger neurotransmitter of the sympathetic nervous system
With which cells do preganglionic sympathetic fibres synapse in the adrenal medulla? Why is this unusual?
- Synapse with chromaffin cells
- Unusual because there is no post-ganglionic fibre!
Where can muscarinic receptors be found?
- Cardiac muscle
- Smooth muscle
- Glands
Where does the parasympathetic nervous system arise from in the CNS?
Brain stem and sacral region (S2-S4)
How long are the pre-/post-ganglionic fibres in the parasympathetic nervous system?
Long pre, short post
Why do we need less parasympathetic innervation than sympathetic?
Because the parasympathetic nervous system supplies less structures
Which organ regions do the parasympathetic nerves from the brainstem supply?
Head, abdomen, thorax
Where do parasympathetic nerves exit the sacral spinal cord (cross-sectionally speaking)?
Ventral horn/ventral root
Why is there rarely a lateral horn in the sacral region of the spine?
Not enough autonomic innervation to form a discrete horn
Which nerves do the sacral spinal nerves form when leaving the spinal cord?
Pelvic splanchnic nerves
Which axons comprise the autonomic plexus?
- Sympathetic postganglionic axons
- Parasympathetic preganglionic axons
+ Some visceral sensory axons
List four major autonomic plexuses
- Cardiac plexus
- Pulmonary plexus
- Abdominal aortic plexus
- Sup and Inf Hypogastric plexus
What neurotransmitters are always released by preganglionic and postganglionic sympathetic fibres?
Pre: Ach
Post: NE
