3.4 Flashcards
what does then nervous system consist of
a complex network of nerve cells called neurons
what organelles do neurons have
- nucleus
- cytoplasm
- cell membrane
- dendrites
- axons
what do dendrites and axons allow neurons to do
carry electrical impulses
what do dendrites do
they carry electrical impulses towards the cell body
what do axons do
carry electrical impulses away from the cell body
what are the 3 types of neurons
- sensory
- inter
- motor
sensory column of table
- has dendrites in contact with sense organ receptors
- dendrites merge to form a dendron which carries impulses to the cell body
- has a short axon which forms connections with inter neurons
inter column of table
- connects sensory neurons to motor neurons
- very short and contained inside the cns
- many dendrites which form many complex connections
motor column of table
- short dendrites which receive impulses from inter neurons
- long myelinated axon which carries nerve impulses to effectors
what are axons surrounded by
a myelin sheath
what does a myelin sheath contain
a fatty material which insulated the axon and increases the speed of impulse conduction
what do glial cells do
provide physical support for neurons and they produce the myelin sheath
what is myelination
the development of myelin sheaths by glial cells.
how long does myelination continue through your life
from birth to adolescence
why are responses to stimuli in first 2 years of life not as rapid/coordinated as those of older child/adult
because myelination happens from birth to adolescence
do some diseases impact the myelin sheath
yes, some destroy it causing a loss of coordination
give example of disease which destroys the myelin sheath
multiple sclerosis
where do neurons connect with other neurons
at a synaptic cleft
what is the name of the neuron before and after the synaptic cleft
the presynaptic cleft and postsynaptic cleft
what do neurotransmitters do
relay impulses across the synaptic cleft
where are neurotransmitters stored and when are they released
in the vesicles in the axon ending of the presynaptic neurons and released into the cleft on arrival
how does the neurotransmitter work
it diffuses across the cleft and binds to receptors on the membrane of the postsynaptic cleft neuron
why must neurotransmitters be rapidly removed as soon as the impulse has been transmitted
to prevent the continuous stimulation of postsynaptic neurons
how can neurotransmitter be removed
- enzyme degradation and reabsorotion if neurotransmitter by presynaptic neuron
- re-uptake of neurotransmitter by presynaptic neuron
