2. neurons and neurotransmitters

Question 1

neurons

Answer 1

basic building blocks of the nervous system
nerve cells that process and transmit messages through electrical and chemical signals
80% in the brain

Question 2

structure of a neuron

Answer 2

structure of all cells is the same but different in size:
dendrites receive signals at the end of the one neuron or from sensory receptors
connected to cell body (includes a nucleus)
along the axon, covered in a fatty layer of myelin sheath, protects axon and speeds up electric impulse
terminal buttons, communicate with next neuron across synapse

Question 3

sensory neurons

Answer 3

carry messages from sensory receptors to the CNS
in: eyes, ears, tongue, skin
convert information from sensory receptors to neural impulses
passed to brain or spinal chord
long dendrites and short axons

Question 4

relay neurons

Answer 4

connect sensory neurons to motor or other relay neurons= can communicate with each other
found in CNS
short dendrites and axons

Question 5

motor neurons

Answer 5

connect CNS to muscles and glands
in the CNS project axons outside the CNS
directly indirectly control muscles
stimulated= release neurotransmitters that binds to receptors on muscles
trigger response= muscle movement
short dendrites and long axons

Question 6

once an action potential reaches the terminal buttons…

Answer 6

the presynaptic neuron releases neurotransmitters and it’s passed onto the next neuron from the synaptic vessel into the synaptic gap

Question 7

neurotransmitters

Answer 7

chemicals that difuse across the synapse to the next neuron
bind to the post synaptic receptor sites

Question 8

re- uptake

Answer 8

neurotransmitter returns to the presynaptic neuron stored for later use
quicker it’s taken up the shorter the effects of the neurotransmitter
enzymes ‘turn off’ neurotransmitters after they’ve stimulated a post synaptic neuron making them ineffective

Question 9

excitation and inhibition

Answer 9

neurotransmitters either have an excitatory or inhibitory effect on the next neuron
influences are summed if net effect is inhibitory= less likely to ‘fire’

Question 10

excitation

Answer 10

a post synaptic neuron becoming positively charged and more likely to fire
e.g adrenaline

Question 11

inhibition

Answer 11

post synaptic neuron becoming negatively charged and less likely to fire
e.g GABA

Question 12

direction of information

Answer 12

one direction
neurons only transmit info one direction at a synapse:
the synaptic vesicles containing the transmitter only released from the presynaptic membrane
receptors for the neurotransmitter only on the postsynaptic membrane
binding of neurotransmitters to receptors enables signal to be passed
diffusion of neurotransmitters= only go from high to low concentration= only travel from presynaptic to the postsynaptic membrane