nervous system Flashcards
what are the two subdivisions of the nervous system
central nervous system
peripheral nervous system
what does the central nervous system inclued
brain, spinal cord
what does the peripheral nervous syetem include
sensory receptors, nerves
what are sensory receptors
neurons or specialized cells that detect stimuli
what type of stimuli do sensory receports detect
temperature, pain, touch, pressure, light
What are neurons
nerve cells: transmit impulses between parts of the nervous system
descfibe sensory neuron:
deliver impulses from receptors to central nervous system.
long dendrites and short axons
describe motor neurons
send messages from central nervous system to “effector cells”(muscles, organs, gland)
short dendrites, long axons
describe interneurons
between sensory and motor neurons
only in central nervous system
sum up sensory input
short axons and dendrites
what is a dendrite
extensions that receive stimuli and deliver it to cell body
what is the cell body
contains the nucleus and organells
what is the axon
delivers impulse from cell body to other neurons or effector
axons and dendrites can be surrounded by what type of cells
schwan cells with layers of fatty myelin tissue
what does myelin do
protects and speeds transmission of imopulse
what are rodes of ranvier
they are gaps between schwan cells on the axons
what does a nerve do
recieces and responds to many stimuli
how does the nerve send its information
electrical impulse (action potential), ion charge
describe resting neuron
- no impulse
- inside of neuron negative relative to outside
- interior contains k
- exterior contains na
- polarity is maintained by sodium/potassium pump
describe nerve stimulation
-rapid change in polarity along axon and dendrite
depolarization, re-polarization
describe depolarization
- stimulus causes change in local membrane charge
- voltage-gated na channels open
- na enters neuron.
- change in polarity inside neuron
repolarization
- na gates close, k channels open
- polarity inside neuron goes back to negative
- na/k concentration is now opposite of resting neuron
describe refractory period (recovery)
- carrier proteins actively transport ions to original position
- no action potential can occur until resting ion concentration is reestablished
what is a synapse
small space between neurons
a point of communication between two neurons, separated
what does presynaptic membranes do
“deliver information” in the form of neurotransmitters
