anatomy and physiology of the nervous system Flashcards
where is the node of Ranvier located on a neuron? And what does it have a high density of?
on the axon. It is the gap between the schwann cells (myelin).
it has a very high density of sodium channels.
what is the axon hillock?
the part of the neuron which connects the cell body to the axon
how does the membrane potential develop?
- the membrane is more permeable to potassium than sodium.
- So, more potassium leaves the cell.
- Electrical forces opposes potassium outflow and favours sodium inflow.
- resting membrane potential develops. (~70mM)
- sodium potassium pumps maintain the sodium potassium gradients.
how dos neuronal action potential develop?
Rising phase:
- Depolarization
- sodium influx via voltage gated sodium channels
- sodium channels inactivated
- refractory period(absolute, relative)
Falling phase:
- repolarisation
- potassium efflux via voltage gated potassium channels
what are the 2 divisions of the PNS?
autonomic and stomatic
what are the divisions of the autonomic nervous system?
sympathetic and parasympathetic division
what neurotransmitter is released by the sympathetic nervous system?
noradrenaline
what receptors does noradrenaline act on?
Adrenoceptors
what neurotransmitter does the parasympathetic nervous system release?
acetyl chloine (ACh)
what receptor does ACh act on?
muscarinic acetylcholine receptors.
what is the neurotransmitters for both sympathetic and parasympathetic ganglia?
Ach acting on nicotinic Ach receptors.
where are parasympathetic ganglia located?
close to or within the target organs
where are the ganglia for the sympathetic NS located?
close to the spinal cord.
what are the 4 main types of cells in the brain?
Neurones
astrocytes
microglia
oligodendrocytes
where does peripheral afferent input go into the spinal cord?
dorsal horne
