Ans Flashcards
What is the ANS responsible for ?
For regulation of visceral functions (heart/lungs/abd content) and
maintainable of homeostasis of the internal environment
What does the ANS consist of ?
Efferent neurons in the peripheral nervous system
What do the efferent neurons control?
They control 3 types of cells:
1-smooth muscle cells
2-cardiac muscle cells
3-gland cells
Is the ANS consciously controlled?
No it’s controlled by the unconscious
What are the divisions of the ANS?
Sympathetic nervous system
Parasympathetic nervous system
Enteric division
What does the ANS consist of?
A 2 neuron chain
What’s the first neuron and the second neuron called ?
Preganglionic neuron (the cell body in the CNS) They synapse in the ganglia with the the second neuron called: post ganglionic neuron
Where do preganglionic neurons be? (In the SANS)
They lie in the intermediolateral cell column between T1 and L2.
How do preganglionic fibres synapse? (SANS)
In paired paravertebral ganglia (22 of these on either side of the spinal cord extending from cervical to sacral region)
What may preganglionic neurons do before synapsing? (SANS)
They may pass up/down the paravertebral ganglia before synapsing
What are the exceptions to pre/post ganglionic synapsing ? (SANS)
Some preganglionic neurons pass through the paravertebral column without synapsing
Preganglionic neurons that pass without synapsing what do they do? (SANS)
These preganglionic neurons eventually synapse with the postganglionic neuron in the prevertebral ganglia
What do post ganglionic neurons do? (SANS)
They innervate the glands, blood vessels and smooth muscles of the abdominal and pelvic viscera
What is an adrenal gland considered to be? (SANS)
A specialised sympathetic ganglia
What do some preganglionic fibres do? (SANS)
They directly innervate adrenal glands
What’s the effect of stimulation ? (SANS)
To release adrenaline/noradrenaline into the blood resulting in a diffuse/wide ranging sympathetic response
Between pre and post ganglionic neurons is what NT? (SANS)
Acetylcholine is released
As there’s 2 neurons m, 2 NTs are needed so which are they? (SANS)
Between pre and post G neurons the NT Is acetylcholine
Between the postganglionic neuron and the effector, noradrenaline is released
What are the receptor subtypes of noradrenaline?
Alpha and beta
What are some minor exceptions in NT..?
Sympathetic cholinergic innervation to some muscle blood vessels and sweat glands
Where are the cell bodies of the preganglionic neurons of the PNS?
They lie in the brain stem and intermediolateral cell column of the sacral spinal cord (cranio-sacral outflow)
Where’s the ganglia of the PNS?
Close to the effector, Sometimes the ganglia (+postGN) are part of the effector
Between the pre and post ganglionic neuron what NT is released? (PNS)
Acetylcholine is released and the receptor subtype is nicotinic
Between the post ganglionic neuron (of the PNS) and the effector what NT is released?
Acetylcholine and the receptor subtype is muscarinic
