neurons

Question 1

converging neural pathways

Answer 1

multiple neurons sending impulses to one neuron. increases the sensitivity to excitatory and inhibitory impulses

Question 2

diverging neural pathways

Answer 2

impulse from one neuron travelling to many neurons, affecting many destinations at a time

Question 3

reverberating neural pathway

Answer 3

one neuron in a pathway sends an impulse to a neuron earlier in the pathway. allows repeated stimulation of the pathway

Question 4

myelin sheath

Answer 4

a layer of insulation that protects the axon of a neuron. increases the rate an impulse travels at. created by glial cells

Question 5

myelination

Answer 5

the growth of the myelin sheath as its not fully developed at birth. continues from birth till adolescence

Question 6

how an impulse travels between neurons

Answer 6

1. an impulse travels down the pre-synaptic neuron
2. vesicles release neurotransmitters that diffuse across the synaptic cleft
3. neurotransmitters bind to receptors at the post-synaptic neurons
4. neurotransmitters removed from the synaptic cleft to avoid continuous stimulation of the receptors

Question 7

re-uptake

Answer 7

the neurotransmitters are reabsorbed by the pre-synaptic neuron

Question 8

enzyme degredation

Answer 8

neurotransmitters broken down by enzymes, the products are then absorbed and used to synthesise new neurotransmitters

Question 9

neuron cell body

Answer 9

contains nucleus and a cytoplasm that contains organelles like many mitochondria, in order to provide energy, and ribosomes, in order to synthesise proteins that synthesise neurotransmitters

Question 10

dendrites

Answer 10

these fibres receive impulses and pass them towards the cell body

Question 11

axon

Answer 11

these fibres carry an impulse away from the cell body

Question 12

excitatory and inhibitory signals

Answer 12

receptor cells in the post-synaptic neuron will determine if the signal is excitatory (increase in action) or inhibitory (decrease in action)

Question 13

weak stimuli

Answer 13

an impulse will only be transmitted across a synaptic cleft if it causes the release of a sufficient number of neurotransmitters, this is the threshold.

Question 14

summation

Answer 14

a single weak impulse will be filtered out as it doesnt trigger the release of enough neurotransmitters. when many axons release their neurotransmitters at the same time or in rapid succession, this releases enough chemicals to fire a response