19. The Nervous System And Neurotransmitters

Front 1

3 types of neuron

Back 1

sensory, inter and motor

Front 2

3 main parts of a neuron

Back 2

dendrite, cell body, axon

Front 3

myelin sheath

Back 3

layer of fatty material that insulates an axon and speeds up impulses

Front 4

glial cells

Back 4

provide physical support to neurons, produce the myelin sheath, maintain the homeostatic environment around neurons

Front 5

blood brain barrier

Back 5

intimate contact between glial cell projections and the capillary wall in the brain

Front 6

synapse

Back 6

the connection between the axon of one neuron and the dendrite of another

Front 7

vesicles

Back 7

contain neurotransmitter in the presynaptic knob

Front 8

receptor molecules

Back 8

can be excitatory or inhibitory

Front 9

threshold

Back 9

the minimum number of neurotransmitter molecules that need to bind with receptors for an impulse to be sent

Front 10

summation

Back 10

the cumulative effect of a series of weak stimuli that together bring about an impulse

Front 11

converge

Back 11

to come together and meet at a common point

Front 12

diverge

Back 12

to branch out from a common point

Front 13

reverberating neural pathway

Back 13

neurons later in the pathway possess axon branches that form synapses with neurons earlier in the pathway

Front 14

plasticity

Back 14

the flexibility of the brain

Front 15

endoprphins

Back 15

natural painkillers that combine with receptors and block the transmission of pain signals

Front 16

dopamine

Back 16

neurotransmitter that when released brings about a pleasurable feeling

Front 17

agonist

Back 17

chemical that binds and stimulates specific receptors, mimics the neurotransmitter

Front 18

antagonist

Back 18

block the receptor sites preventing the neurotransmitter acting on them

Front 19

inhibitor

Back 19

prevent the removal of the neurotransmitter from the synaptic cleft either by inhibiting the enzyme or blocking reabsorption

Front 20

desensitisation

Back 20

repeated use of agonist drug leads to repeated stimulation, nervous system compensates and receptors reduce in number

Front 21

sensitisation

Back 21

repeated use of an antagonist blocks neuroreceptors, the nervous system responds by increasing the number of receptors