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higher biology > 3.4 > Flashcards

3.4 Flashcards

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1
Q

what does then nervous system consist of

A

a complex network of nerve cells called neurons

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2
Q

what organelles do neurons have

A
  • nucleus
  • cytoplasm
  • cell membrane
  • dendrites
  • axons
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3
Q

what do dendrites and axons allow neurons to do

A

carry electrical impulses

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4
Q

what do dendrites do

A

they carry electrical impulses towards the cell body

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5
Q

what do axons do

A

carry electrical impulses away from the cell body

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6
Q

what are the 3 types of neurons

A
  • sensory
  • inter
  • motor
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7
Q

sensory column of table

A
  • 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
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8
Q

inter column of table

A
  • connects sensory neurons to motor neurons
  • very short and contained inside the cns
  • many dendrites which form many complex connections
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9
Q

motor column of table

A
  • short dendrites which receive impulses from inter neurons
  • long myelinated axon which carries nerve impulses to effectors
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10
Q

what are axons surrounded by

A

a myelin sheath

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11
Q

what does a myelin sheath contain

A

a fatty material which insulated the axon and increases the speed of impulse conduction

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12
Q

what do glial cells do

A

provide physical support for neurons and they produce the myelin sheath

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13
Q

what is myelination

A

the development of myelin sheaths by glial cells.

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14
Q

how long does myelination continue through your life

A

from birth to adolescence

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15
Q

why are responses to stimuli in first 2 years of life not as rapid/coordinated as those of older child/adult

A

because myelination happens from birth to adolescence

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16
Q

do some diseases impact the myelin sheath

A

yes, some destroy it causing a loss of coordination

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17
Q

give example of disease which destroys the myelin sheath

A

multiple sclerosis

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18
Q

where do neurons connect with other neurons

A

at a synaptic cleft

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19
Q

what is the name of the neuron before and after the synaptic cleft

A

the presynaptic cleft and postsynaptic cleft

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20
Q

what do neurotransmitters do

A

relay impulses across the synaptic cleft

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21
Q

where are neurotransmitters stored and when are they released

A

in the vesicles in the axon ending of the presynaptic neurons and released into the cleft on arrival

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22
Q

how does the neurotransmitter work

A

it diffuses across the cleft and binds to receptors on the membrane of the postsynaptic cleft neuron

23
Q

why must neurotransmitters be rapidly removed as soon as the impulse has been transmitted

A

to prevent the continuous stimulation of postsynaptic neurons

24
Q

how can neurotransmitter be removed

A
  • enzyme degradation and reabsorotion if neurotransmitter by presynaptic neuron
  • re-uptake of neurotransmitter by presynaptic neuron
25
Q

what does the type of receptor that the neurotransmitter bind to determine

A

whether the signal is excitatory or inhibitory

26
Q

what does an excitatory signal do

A

cause an increase in action eg. cause muscles to contract

27
Q

what does an inhibitory signal do

A

cause a decrease in action eg. slow heart rate

28
Q

what needs to happen to transmit an impulse

A

a min number of neurotransmitter molecules must attach to receptors in order to reach the threshold on the postsynaptic membrane

29
Q

what do synapses do to weak stimuli

A

filter them out

30
Q

why do weak stimuli arise

A

insufficient secretion of neurotransmitters

31
Q

what can summation of weak transmitters do

A

release enough neurotransmitter to trigger an impulse

32
Q

can convergent pathways release enough neurotransmitter to reach the threshold and trigger impulses

A

yes

33
Q

what are endorphins

A

a neurotransmitter that stimulate neurons involved in reducing the intensity of pain

34
Q

what are increased levels of endorphins connected with

A

feelings of pleasure

35
Q

what causes feelings of pleasure from endorphins

A

eating, sex and prolonged exercise

36
Q

what activities cause endorphin production to increase

A
  • severe injury
  • prolonged and continuous exercise
  • stress
  • certain foods ( eg choc & chillis)
37
Q

what is dopamine

A

a neurotransmitter that induces feelings of pleasure

38
Q

how does dopamine increase feelings of pleasure

A

by reinforcing particular behaviour by activating a reward pathway in the brain

39
Q

what does the reward pathway involve

A

neurons which secrete or respond to dopamine

40
Q

when is the reward pathway activated

A

when an individual engages in behaviour which is beneficial to them eg. eating when hungry

41
Q

what types of drugs can be used to treat conditions related to neurotransmitters

A
  • agonistic drugs
  • antagonistic drugs
42
Q

what are agonistic drugs

A

chemicals which bind to and stimulate specific receptors which mimics the action of a neurotransmitter at a synapse

43
Q

what are antagonistic drugs

A

chemicals that bind to specific receptors blocking the action of a neurotransmitter at a synapse

44
Q

what do other types of drugs they treat neurotransmitter disorders do

A
  • they inhibit the enzymes that degrade neurotransmitter
  • they inhibit reuptske of the neurotransmitter at the synapse causing an enhanced effect
45
Q

what do recreational drugs do

A

act as agonists or antagonists

46
Q

how do recreational drugs interact with neurotransmitters

A
  • they can stimulate the release of transmitters
  • mimic their actions (agonists)
  • block their binding (antagonists)
  • inhibit their enzyme degradation
  • inhibit their reuptake
47
Q

what happens when recreational drugs affect neurotransmission in the reward pathway

A

it alters a persons neurochemistry which changes their mood, cognition, perception and behaviour.

48
Q

what causes drug addiction

A

repeated use of drugs which act as antagonists

49
Q

what do antagonists do

A

block specific receptors which causes the nervous system to increase both the number and sensitivity of these receptors

50
Q

what does drug sensitisation lead to

A

addiction where the individual craves more of the drug

51
Q

what causes drug tolerance

A

repeated use of drugs which act as agonists

52
Q

what agonists do

A

stimulate specific receptors causing the nervous system to decrease both the number and sensitivity of these receptors

53
Q

what does desensitisation of drugs lead to

A

drug tolerance where the individual must take more of the drug to get an effect

higher biology (24 decks)

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