ANS Flashcards
Give a brief overview of the ANS.
- Includes both central and peripheral nerve components
- Controls body elements such as smooth muscle, cardiac muscle and glands often unconsciously
What is a ganglion?
A ganglion is a collection of neuronal bodies.
How does the ANS maintain homeostasis (basic organisation)?
Continual flow of sensory afferent input from receptors in organs and efferent motor output to the same effector organs.
What two subunits is the ANS divided into and what do they control?
- Sympathetic and parasympathetic
- Parasympathetic system tends to control rest and relaxation, whereas the sympathetic nervous system tends to control excitement, activity and classically “Fight or Flight”
In the parasympathetic system, where do motor nerves emerge from?
Cranial nerves (brainstem) and the sacral spinal cord segments - craniosacral.
Why do sympathetic motor fibres originate from?
The thoracolumbar area - between thoracic and lumbar vertebrae.
How many neurons does the ANS system require and where do these neurons meet?
2 - in the ganglia.
Where are sympathetic ganglia found?
- Closer to the spinal chord
Where are parasympathetic ganglia found?
Way out from the spine, near, or even inside, their effector organs.
What are the names of the two neurones around the ganglia?
Preganglionic and postganglionic cells
What is the difference in the two neurons for the sympathetic vs parasympathetic?
Sympathetic - preganglionic fibres much shorter.
Parasympathetic - postganglionic much shorter.
Sympathetic - what neurotransmitter is released from pre ganglion?
Acetylcholine (Ach)
Sympathetic - what neurotransmitter is released from post ganglion?
Noradrenaline
What is the other sympathetic response to stress?
Ach released from pre ganglionic fibres –> adrenal glands - adrenal medulla releases adrenaline and noradrenaline.
Define neurotransmitter.
Released from a neuron and travelling across a synapse.
