Nervous System Flashcards
What does the nervous system comprise of?
Central nervous system
Peripheral nervous system
What does the Central nervous system comprise of?
Brain
Spinal cord
What does the Peripheral nervous system comprise of?
Somatic nervous system - voluntary
Autonomic nervous system - involuntary
What are names given to nerves going to and from the central nervous system?
Efferent - away from the CNS (sensory neurone)
Afferent - toward the CNS (motor neurone)
E - Exit
A - Affinity
What are some cells involved in the CNS?
Nerve cells - neurones (they are electrically active)
Supporting cells - neuroglia, glial cells
What is a nerve?
A bundle of axons surrounded by connective tissue which binds them together
What is the sensory neurone made up of? (in the direction of the nerve impulse)
Dendrites Dendron Soma (cell body) - in the middle Axon Branches of axon Synaptic knob (terminal)
Potentially with myelin sheath and nodes of Ranvier
What is the intermediate (multipolar) neurone or interneurone made up of?
Cell body in the middle
Axon and dendrites, with branches of axon and dendrites attached all around the cell body
What is the motor neurone made up of? (in the direction of the nerve impulse)
Some (cell body) at the end, surrounded by dendrites
One large axon
Branches of axon
Motor end plate (terminal) - forms neuromuscular junction
Potentially with myelin sheath and nodes of Ranvier
How to remember the direction of the nerve impulse?
Dendrites - dick in
Axon - away
What do dendrites do?
Subdivisions of the dendron which transmit nerve impulses towards the cell body
What does the Soma contain?
Nucleus
Large amounts of rough endoplasmic reticulum (for production of proteins and neurotransmitters
What are the nodes of Ranvier?
Gaps between adjacent schwann cells where there is no myelin sheath
Which neurone is faster myelinated or unmyelinated, why?
Myelinated is faster
The fatty sheath of myelin around the axon acts as a electrical insulator preventing action potentials forming
At the nodes of ranvier, a localised current can form, s the action potential can ‘jump’ from node to node = saltatory conduction
How can neurones be classified by their actions?
Excitatory neurones - increase the activity of target cells
Common transmitter is glutamate
Inhibitory neurones - decrease the activity of target cells
Common transmitter is GABA (gamma-amino butyric acid)
How is the neurone structurally organised?
The nucleus and the tract are in the CNS
The nerve and the ganglion are in the PNS
What is the nucleus and the tract?
Nucleus - a collection of neuronal cell bodies in the CNS
Tract - a group of functionally related axons in the CNS
What is the nerve and the ganglion?
Nerve - a bundle of axons in the PNS
Ganglion - a collection of cell bodies in the PNS (no longer a nucleus)
What are glia cells in comparison to neurones?
Glia only have one ‘process’ whereas neurones have two (axons and dendrites)
Glia don’t carry action potentials, but do have a resting potential
Glia don’t have synapses
What are the two catagories of glial cells?
Myelinating glial cells
Supporting glial cells
What are the myelinating glial cells?
Schwann cells - provides myelin to neurones in the PNS
Oligodendrocytes - provides myelin to neurones in the CNS
Whar are the supporting glial cells?
Astrocytes - transport nutrients to neurones, clean up brain ‘debris’, hold neurones in place
Satellite - Gives physical support to (sensory) neurones in the PNS
Microglia - ‘the immune cells of the brain’ clean up CNS debris (to prevent toxic build up)
What is the somatic nervous system made up of?
Voluntary nervous system
Motor neurones (efferent) Sensory neurones (afferent)
What are some factors of the sensory neurone?
Lies within the PNS
Can be both un/myelinated
Afferent - towards the CNS
Neurotransmitter - glutamate
What are some factors of the motor neurone?
Lies within the CNS
Heavily myelinated
Efferent - away from the CNS
Neurotransmitter - acetylcholine
What is the autonomic nervous system made up of?
Involuntary controls: heart rate, blood pressure and gut movements
Sympathetic - fight or flight
Parasympathetic - rest and digest
Describe the sympathetic structure?
Soma and dendrites at the end
Short preganglionic myelinated axon
Terminal closer to the CNS, with a synapse to a ganglion (acetylcholine transmitter to nicotinic receptor)
Long postganglionic axon, that branches extensively into multiple terminals with noradrenaline transmitter to the target/effector
Describe the parasympathetic structure?
Soma and dendrites at the end
Long preganglionic myelinated axon
Terminal towards the target, with a synapse to a ganglion (acetylcholine transmitter to nicotinic receptor)
Short postganglionic axon, that branches minimally to one terminal with acetylcholine transmitter to the target/effector
What is another element of the autonomic nervous system?
The enteric nervous system - is one of the main divisions of the ANS
It works in the gastrointestinal tract
It can work independently however can be influenced by the vagus (parasympathetic) and sympathetic chain
