lecture 8: nervous system Flashcards
name the 2 parts of the nervous system
central nervous system (CNS)
peripheral nervous system (PNS)
briefly describe CNS
brain
spinal cord
briefly describe PNS
nerves (cranial and spinal)
ganglia (cluster of neuron cell bodies)
cluster of cell bodies in CNS
nuclei
name the 3 functions of nervous system
sensory input (PNS)
integration (CNS)
motor output (PNS)
describe sensory input (PNS)
response to external and internal stimuli
describe integration (CNS)
interpretation of sensory input
decides appropriate response
describe motor output (PNS)
conduction of signals from the CNS to effector cells
what are neurons
cells specialized for transmitting electrical and chemical signals
name parts of a neuron
cell body
fiber like extensions
what do the fiber like extensions of a neuron consist of
dendrites
axons
describe dendrites
convey signals towards cell body
short and numerous
describe axons
conduct impulses away from cell body
long single processes
some are insulated by myelin sheath
ends in axon terminal
what do axon terminals do
relay signals to other cells by releasing neurotransmitters
form synapses (junctions) between pre-synaptic and post-synaptic neurons
describe synapses
nerves communicate via synapses
neurotransmitter are release from pre-synaptic neuron and act on a post-synaptic neuron
describe pathway (through neuron)
stimuli
dendrites
cell body
axon hillock
axon
axon terminal
synapse
dendrites
cell body
axon hillock
axon
axon terminals
synapse
effector
describe synapse (channels)
neurotransmitters bind to ion channels on post synaptic dendrites and causes hyper (inhibitory) or de (excitatory) polarization
inhibitory - K+ moves out
excitatory - Na+ moves in
(2 separate ion channels)
the time of response is dependent on what
speed of info transmission is dependent on number of synapses (number of neurons) in pathway
describe nerves
PNS
nerve = many axons bundled together
what is ganglion
PNS
all the axons synapsing
name the 3 types of neurons
sensory
motor
interneuron (association neuron)
describe sensory neurons
carry impulses from sensory receptors towards CNS
(afferent - towards)
cell bodies in PNS ganglia
describe motor neurons
carry impulses from CNS to effectors
(efferent - leading away)
most cell bodies in CNS (except for some autonomic neurons)
describe interneuron (association neuron)
connect sensory and motor neuron
shuttle signals through CNS pathways
99% of neurons
describe optice nerve/tract
optic nerve - pns
optic tract - cns
describe structure of spinal cord
bundles of axons emerge from the back (dorsal root) and front (ventral root) of the spinal
cord on either side and finger to form the spinal nerves
dorsal root contains
sensory neurons
ventral root contains
motor neurons
dorsal root ganglion contains
cell bodies of sensory neurons
name difference between brain and spinal cord (organization of matter)
spinal cord has grey matter in center
brain has grey matter as outer layer
describe flow of information through the nervous system
(ex withdrawal reflex)
receptor
sensory neuron
integration center (spinal cord)
motor neuron
effector
describe reflexes
involuntary response to stimuli (without conscious input)
what is a reflex arc
simple nerve circuit
why does doctor check your reflexes
gives info about health of nervous system
describe patellar reflex steps
receptor
sensory neuron
integration (spinal cord, few neurons, not complex)
motor neuron
effector
describe patellar reflex (generally)
2 neuron pathway BUT
also hamstrings must be relaxed for quads to contract
where are reflexes integrated
spinal cord and brain
name reflexes integrated in spinal cord
patellar reflex
withdraw reflex
name reflexes integrated in brain
involuntary
pupillary
swallowing
vomiting
breathing
blinking
sneezing
eyes tearing up
what are meninges
layers of connective tissues that cover the brain and spinal cord
name the 3 layers of meninges (and correct order outer to inner)
dura mater
arachnoid mater
pia mater
what is cerebral spinal fluid (CSF)
clear colourless fluid that surrounds brain and spinal cord
what contains CSF
ventricles - network of cavities within brain and spinal cord
name the functions of CSF
protection
buoyancy (1400g—>50g)
excretion of waste products
transport of hormones
what are glia
supporting cells
name the glial in CNS
astrocytes
oligodendrocytes
ependymal cells
microglial cells
describe astrocytes
provide structure and metabolic support
mediate exchange between capillaries and neurons and help form the blood brain barrier
describe oligodendrocytes
form myelin sheath around axons