cells of the nervous system Flashcards
neuron organisation: recall the definition, structure, and function of a neuron (including nucleus, soma, dendrites, axon, synapses, lamina, synapses and fibre tract)
neuronal function
basic structural and functional unit; generates and conducts electrical signals; comunnicate with one another via synapse; supported by neuroglia; secretory
neuronal structure: components
large nucleus, prominent nucleolus, abundant RER, well-developed Golgi, abundant mitochondria, highly organised cytoskeleton
nueronal structure: diversity
similar to other cells; diversity achieved by differences in number and shape of processes determined by location and function
consequences of neuronal diversity
more/less vulnerable to degeneration in CNS conditions (Alzheimers, Parkinsons, MS, ALS)
why abundant RER and well-developed Golgi
larger, produces and secretes lots of proteins
pyramidal nueronal cell features
primary dendrites leave at three poles - divide to secondary and tertiary dendrites
dendrites: function and structure
major area of reception of incoming information; spread from cell body and branch frequently; greatly increases SA; often covered in protrusions (spines) which receive majority of synapses
spinal plasticity
one of the most plastic elements of nervous system - easily damaged
Purkinje: location, function and structure
in cerebellum; large inhibitory neurones; 2D spinal tree structure; responsible for fine movement
axons: function, branching, properties, structure, location
conduct impulse away from cell body; emerge at axon hillock; only one per cell; may branch after leaving cell body and at target; prominent micro-tubules and neurofilaments; can be myelinated (exposed at node of Ranvier) or unmyelinated; cable properties
why do axons have prominent microtubules
to transport vesicles from cell body to target
why do axons have neurofilaments
high tensile strength as very thin
axon cable properties
same diameter to maintain same speed of electrical conduction
node of Ranvier: function and properties
where signal is amplified; where Na+ channels are present
paranode
end loops of myelin attached to membrane
juxtaparanode
K+ channels so gap between K+ and Na+ channels
axon terminals
axon branch extensively at target; form synaptic terminals with target
axonal damage in MS
axon compressed and transected so swelling at end - all vesicular proteins build up
subtypes of neurones
pseudounipolar, bipolar, multipolar
pseudounipolar: features and example
dorsal root ganglion; sensory neurones; two fused processes axonal in structure (bypass cell body)
bipolar: feature and examples
two processes, white matter and retina
multipolar I: features and examples
Golgi type I multipolar; highly branched dendritic trees; axons extend long distances; pyramidal cells of cerebral cortex; Purkinje cells of cerebellum; anterior horn of spinal cord; retinal ganglion; most susceptible to degeneration
multipolar II: features and examples
Golgi type II multipolar; highly branched dendritic trees; short axons; axons terminate quite close to cell body of origin; stellate cells of cerebral cortex and cerebellum
functional classification of neurones
sensory, motor and inter
interneurones function
links other neurones; responsible for modification, coordination, integration, facilitation and inhibition of sensory input to give a motor output
