CNS Flashcards
(21 cards)
What are the main function of the CNS
Sensation- changes in body and environment
Integration- makes sense of changes
Response- initiates a response
What are the 2 principle types of cell in CNS
Neurones- functional unit ( help transmit nerve impulse)
Neuroglia - support and protect neurones ( Maintain homeostasis )
3 characteristics of a neurone
Cell body- core section
Axon - long tail like structure
Dendrite- fibrous roots that branch out of cell body and communicate with adjacent neurones
What is the action potential of the nerve cell
Occurs when neurone sends information down axon away from cell body
Nerve fires when depolarised ( inside of cell is positive)
And stops firing when polarised ( inside of cell is negative)
Main characteristics of action potential of the nerve cells
Depolarisation is Na dependent
Na goes in and K goes out
Impulse needs to reach action potential to carry on- if not reached message wont continue to be transmitted
Resting membrane potential is -70mV
How do the drugs modulate the nerve firing
deter cell depolarisation by blocking Na and Ca channels
Render it negatively charged by leaving K Chanel’s open
What is Saltatory conduction
Way an electrical impulse skips from node to node down the length of the axon
Only occurs in myelinated nerves
Dramatically increases conduction velocity
Impulse jumps between nodes of ranvier
Speed and nerve impulse are dependent on size and type of nerve ..explain
Large - myelinated A fibres = fast motor ( sharp, stabbing acute pain)
Small unmyelinated - C fibres = slow (achy or throbbing pain, itch, cough)
What is a synapse
Junction between 2 nerve cells - impulses pass by diffusion or neurotransmitter
What is antidromic conduction
Conduction of nerve cells in a reverse direction- back tracks
What are neurotransmitters
Chems released into synaptic cleft
100 or more varieties in brain
Bind to post synaptic receptors
Neurotransmitter dysfunction implicated in mental health
4 groups of neurotransmitters?
Biogenic- ACH, monoamines, noradrenaline
Amino acids- GABA, glutamate, glycine
Peptides - endorphins, enkephalins
Other- nitric oxide, adenasine
Noradrenaline is produced in?
CNS
Adrenaline is produced in?
Endocrine system
How do neurotransmitter work
Stored in the axon terminals on neurone in small asks called synaptic vesicles
Presynaptic nerve excited by electrical signal (action potential), releases neurotransmitter into synaptic cleft
Pre synaptic nerve excited by electrical signal (action potential) releases neurotransmitters into synaptic cleft
When in the synaptic cleft the neurotransmitter interacts with the post synaptic receptors and cause a reaction to occur in the post synaptic neurone. This increases or decreases the likeliness the post synaptic neurone will become activated and fire an action potential
What is saltatory conduction
describes the way an electrical impulse skips from node to node down the full length of an axon
Signal jumps from one node of ranvier to another down a myelinated neuron
What are the main characteristics of the parasympathetic nervous system? (5)
Concerned with conservation and restoration of energy
Otherwise known as ‘cranio-sacral’ outflow
Long pre ganglionic fibre, short post ganglionic fibre
Neuro transmitter Acetylchlorine (ACh) acts on nicotinic and muscarinic receptors
Responsible for cholinergic transmission
(A substance (or ligand) is cholinergic if it is capable of producing, altering or releasing ACh)
What are the main characteristics of the sympathetic nervous system? (5)
Otherwise known as ‘thoracolumbar’ outflow
fight or flight
Short pre ganglionic fibre, long post ganglionic fibre
Neurotransmitter ACh pre ganglionic and noradrenaline post ganglionic
a and b receptors
Nicotinic receptors are
Nicotinic (nAChR) - coupled to cation channels. Membrane depolarisation and fast excitatory transmission receptors
Muscarinic receptors are
Muscarinic (mAChR) - G protein coupled receptors with 5 sub types
(M2 = cardiac and M3 = smooth muscle)
What is axoplasmic flow?
Axoplasmic flow is the movement of neurotransmitters from the neurone cell body to where it needs to be ? Axon terminal
