Autonomic Nervous System 1 Flashcards
What is the other name for autonomic NS
The Visceral motor nervous system
What are the subsections of the autonomic NS
Parasympathetic NS and the Sympathetic NS
What do the somatic and visceral/autonomic NS supply?
Somatic - skeletal muscle
Autonomic - Smooth muscle, glands, cardiac muscle, adipocytes
In the autonomic NS what does the two neuron system consist of?
Pre-ganglionic fibres that originate from the CNS
Post-ganglionic fibres that originate from autonomic ganglia
Of the sympathetic NS where do the pre/post ganglionic fibres originate from?
Pre-ganglionic - Thoracolumbar (short pre-ganglionic)
Post-ganglionic - Paravertebral chain or prevertebral ganglia (long post-ganglionic)
Of the parasympathetic NS where do the pre/post ganglionic fibres originate from?
Pre-ganglionic - craniosacral (long pre-ganglionic fibres)
Post-ganglionic - In or near the target organ (short post-ganglionic)
What are the target organs of the parasympathetic nervous system?
- Eyes
- Lacrimal Gland
- Salivary glands
- Hear, lungs and upper GI (supplies by vagus n)
- Lower GI, bladder and genitalia.
What are the target organs of the Sympathetic NS?
- Structures in head and neck such as blood vessels, salivary glands etc
- Heart and lungs
- Adrenal medulla
- Liver, GI, bladder and genitalia
- Blood vessels and sweat glands
When pre-ganglionic sympathetic neurons enter the paravertebral ganglion/chain, what are the four options it can do?
- Enter the paravertebral chain and ascend in the chain to synapse at a ganglion higher up
- Pre-ganglionic fibres enter the chain and synapses in a ganglion at the same level then passes out with the spinal cord at that level
- Enters paravertebral chain and descends to synapse at a ganglion at a lower level
- Pre-ganglionic fibre doesn’t synapse in paravertebral chain but heads out as a splanchnic nerve and synapses in a prevertebral ganglion and then supplies contents of abdomen.
Try draw the autonomic motor reflex
Explain why you can get referred pain
Visceral sensory neurons synapse at the same spinal segment that gives rise to sensory information for other areas. So damage to the heart can cause pain in the shoulder.
What are the PSNS and SNS effects on the heart
PSNS - Decreases heart rate
SNS - Increases heart rate and force of contraction
What are the PSNS and SNS effects on the digestive tract
PSNS - Increases motility and secretion
SNS - Decreases motility and secretion
What are the PSNS and SNS effects on the lungs
PSNS - Bronchoconstriction
SNS - Bronchodilation
What are the PSNS and SNS effects on the urinary bladder
PSNS - Release of urine (contraction of detrusor muscles and relaxation of internal sphincter muscle)
SNS - urine retention (relaxation of detrusor muscles and contraction of internal sphincter)
Describe an autonomic nervous system effect where both PSNS and SNS are causing innervation at the same target
The eye;
Sympatheric NS innervates the pupillary dilator muscles causing mydriasis
Parasympathetic NS innervates pupillary constrictor muscles causing miosis
What are some rules of the PSNS and SNS
where do pre-ganglionic sympathetic fibres synapse on the adrenal gland? and what does this release?
They synapse on chromaffin cells which release adrenaline and noradrenaline
All pre-ganglionic neurons of the PSNS and SNS release what?
Acetylcholine which binds to nicotinic receptors.
All postganglionic PSNS neurons release what?
ACh that binds to muscarinic
What do most postganglionic sympathetic neurons release? what do the others release?
Most release noradrenaline. Some release Ach (sweat glands)
Explain what varicosities of the ANS is
Chain like network of varicosities exist where neurotransmitters are released onto the surface of smooth muscle cells
Here there´s synapse between post-ganglionic fibres and target tissue
Explain the effects of the ANS on the bladder
