How nerves work 1 Flashcards
why does the nervous system exist
to send rapid signals throughout the body
what does the peripheral nervous system (PNS) do?
carries info in and out of the CNS
which type of information enters the spinal chord via the ventral root?
motor
which type of information enters the spinal chord via the dorsal root?
sensory
What is a ganglion
cluster of neurons (ganglion) where the cell bodies of sensory neurons are found
there is only a ganglion on the dorsal root of spinal nerve
Where do motor neurons have their cell bodies?
in the ventral horn (inferior part of grey matter in spinal cord)
what is a pseudoganglion
it looks like a ganglion, but only has nerve fibers and has no nerve cell bodies.
how does sensory info enter the S.C?
Via the dorsal horn (posterior)
how does motor info leave the S.C?
via the ventral horn (anterior)
what happens at the spinal nerve?
the dorsal and ventral roots join and become mixed here. This then leaves the intervertebral foramen laterally and branches into dorsal and ventral rami.
what does the ventral ramus supply
skin, muscles and bones of anterolateral sides of trunk as well as the entire upper and lower limbs
what does the dorsal ramus supply?
posterior side of trunk only (don’t supply the limbs at all)
what are dendrites?
they receive info (like the ears of cell)
cell body (soma)
soma is effectively the nucleus- it makes things like proteins
what is the axon hillock?
contains the machinery to fire an action potential to another neuron
axon terminals
releases a neurotransmitter that binds to receptor on dendrites of other cells and tells them what to do
what are the 3 main types of neurons?
afferent - responds to something in PNS and brings info into CNS (like pressure on skin, temp etc)
efferent- motor neurons- takes out of CNS and synapses onto an effector to make a response
inter-neuron- they look at sensory info and decide amongst themselves which motor neurons to turn on in CNS ie what to send out via efferent neuron
what is glia? and give 3 examples of cell types
connective tissue of nervous system
Astrocytes
oligodendrocytes
microglia
what are astrocytes and what do they do?
they are star shaped glia cell of CNS
they maintain external environment for neurones
they surround blood vessels + produce blood brain barrier
what are oligodendrocytes and what do they do?
at type of glia cell
responsible for myelination of nerves in CNS- myelin helps insulate/ protect axons
Schwaan cell’s role?
myelination in PNS
what do microglia do?
help mop up infection if it occurs
act like a phagocytic hoover
carry out phagocytosis
what is myelination?
form a myelin sheath around a nerve to allow the nerve impulses to move more quickly
what are the 4 types of lobe in the cerebrum
frontal, temporal, parietal and occipital
