Brain function 1 Flashcards
what is a neuron ?
chemical and electrical info and communication cells
variable sizes and structure throughout the nervous system
what is the neurons cellular constituents ?
microtubules (transportation)
neurofibrils (structural support)
Nissl substances (protein synthesis )
what are the three components of the neuron ?
cell body (soma )
dendrites
axons
where is cell body located ?
The CNS
What is dendrites ?
receptive portion of the neuron
sends impulses to the cell body
what is the dendritic zone ?
receptive portion of the neuron receives stimulus and continues further conduction
what is the axon?
carry nerve impulses away from cell body
what is axon hillock ?
is a cone shaped , organelle - free area where the axon leaves the cell body
where does action potential begins ?
axon hillock
what insulates the axon ?
myelin maintained and formed by the Schwann cells
what are nodes of Ranvier ?
regular interruptions of the myelin sheath
what is the neurilemma ?
Schwann sheath
how can neurons be classified ?
basis of the number of processes extending from cell body
what are multipolar neurons ?
each with one axon and two or more dendrites
most common
what are bipolar neuron ?
with one dendrites and one axon
comprise the sensory neurons of the retina , olfactory epithelium and the inner ear
what are unipolar / pseudounipolar neuron ?
includes other sensory neurons
each have single process that bifurcates close to the perikaryon
longer branch extending to peripheral ending to CNS
What are anaxonic neurons ?
with many dendrites but no true axon
do not produce action potential
is a motor neuron multipolar ?
yes
what are sensory neurons ?
transmits impulses from peripheral sensory receptor to the CNS
Are transmitted via an afferent pathway
(Afferent = arrive )
what are associational / interneurons ?
transmits impulses neuron to neuron
what are motor neurons ?
transmits impulse from the CNS to an effector organ
transmitted via efferent pathway ( efferent = exit)
what is neuroglia ?
nerve glue
what are the four types of neuroglia ?
astrocyte
microglial cell
ependymal cell
oligodendrocyte
what are Schwann cells also called ?
neurolemmocytes
what type of cells are schwann cells ?
glial
what do Schwann cells do ?
form and maintain myelin sheath
what is somatic nervous system ?
voluntary movement
what is the autonomic nervous system ?
involuntary movement
what are synapses?
regions between adjacent neurons
impulses transmitted across synapse by electrical or chemical conduction
what is a axoaxonic synapse ?
between axons
what is a axosomatic synapse?
axon to cell body
what is a axodendritic synapse ?
axon to dendrite
what is dendrodentritic synapse ?
dendrite to dendrite
what happens to neurons and neuroglia when ageing ?
gradual loss
what happens to ventricles when the brain ages?
progressive loss of cell lining ventricles
what happens to pigmentation on the brain when ages ?
increase in lipofuscin (brown ) and neuromelanin ( black )
what is the hippocampus ?
memory and skill acquisition of the brain
what are the NMJ dysfunction ?
inflammation
mitochondrial dysfunction and oxidative stress
neurodegeneration
what are some structural changes when ageing in the nervous system ?
decreased number of neurons
decrease brain weight and size
fibrosis and thickening of the meninges
narrowed gyri and widened sulci
increased ventricles
what are some cellular changes to the nervous system when ageing ?
decreased myelin
deposition of lipofuscin
presence of senile plaques
multiple neurofibrillary tangles
lewy bodies
