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A-level Biology > grey matter > Flashcards

grey matter Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what do dendrites do?

A

transfer nerve impulses to the cell body

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2
Q

what do axons do?

A

transfer nerve impulses away from the cell body

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3
Q

what is a myelin sheath?

A

lipid insulation of an axon

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4
Q

how is a myelin sheath created?

A

lipids are secreted by schwaan cells

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5
Q

what is the soma?

A

cell body of a neurone

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6
Q

what are the nodes of ranvier?

A

gaps inbetween the myelin sheath

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7
Q

what does a sensory neurone do?

A

carry impulses from the receptor to the CNS

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8
Q

what does a relay neurone do?

A

carry impulses from the CNS to the motor neurone

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9
Q

what does the motor neurone do?

A

carry impulses from the CNS to the effector

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10
Q

name 3 advantages of a myelin shieth?

A
  • speeds up the impulse
  • protect neurone from damage
  • protect neurone from interferance
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11
Q

what are the 2 parts of the peripheral nervous system?

A
  • autonomic = involuntary
  • somatic = voluntary
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12
Q

what are the 2 parts of the autonomic nervous system?

A
  • parasympathetic
  • sympathetic
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13
Q

what is the sympathetic nervous system responsible for?

A

active and alert responses

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14
Q

what is the parasympathetic nervous system responsible for?

A

rest and digest responses

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15
Q

describe the relationship between the sympathetic and parasympathetic nervous system?

A

antagonistic

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16
Q

name the 2 muscles in control of pupil size?

A
  • circular
  • radial
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17
Q

where are the radial and circular muscles located?

A

the iris

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18
Q

describe the relationship between the radial and circular muscles?

A

antagonistic

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19
Q

describe the process of pupil dilation?

A
  • nerve impulses sent along the optical nerve at low frequency
  • impulses reach sympathetic motor neurones, sent to radial muscles
  • radial muscles contract, more light reaches the retina
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20
Q

describe the process of pupil constriction?

A
  • nerve impulses sent along the optical nerve at high frequency
  • impulses reach parasympathetic motor neurones, sent to circular muscles
  • circular muscles contract, less light reaches the retina
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21
Q

define resting potential?

A

state of nerve fibres when not conducting

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22
Q

what causes a resting potential?

A
  • imbalance in NA and K ions
  • difference in permeability to ions in the cell membrane
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23
Q

what charge is the axon outside?

A

+

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24
Q

what charge is the axon inside?

A

-

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25
Q

what is the potential difference when there are no impulses?

A

-70mv

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26
Q

name the carrier protein within neurones?

A

sodium-potassium pump

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27
Q

what ratio does the sodium-potassium pump move ions in?

A

3 NA out for every 2 K in

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28
Q

is an unstimulated nerve cell polarised or depolarised?

A

polarised

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29
Q

is an stimulated nerve cell polarised or depolarised?

A

depolarised

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30
Q

name the 5 stages that occur after a nerve cell receives an appropriate stimulus?

A

1) NA channels open after stimulus, more NA diffuses into the cell making the inside less negative
2) once -55mv is reached, more NA channels open, creating a potential difference of +40mv, end of depolarisation
3) start of repolarisation by NA channels closing and K opening
4) K diffuses out of the cell and eventually restores resting potential, channel closing is delayed, so there is brief hyperpolarisation
5) resting potential is achieved with the sodium potassium pump

31
Q

what is the threshold value?

A

-55 mv

32
Q

what happens if a stimulus does not reach the threshold value?

A

a failed initiation

33
Q

what is a refractory period?

A

state of recovery that occurs after a neuron has fired an action potential

34
Q

describe the absolute refractory period?

A

no stimuli can cause an action potential, lasts 1ms

35
Q

describe the relative refractory period?

A

an action potential can be caused if the stimulus is very high

36
Q

how does a myelin shieth increase the speed of impulses?

A

myelin changes charge on each end so impulses can jump across nodes of ranvier by saltatory conduction

37
Q

what does the presynaptic membrane do?

A

release neurotransmitters

38
Q

what does the postsynaptic membrane do?

A

recieves neurotransmitters

39
Q

what are the 2 main types of neurotransmitters?

A
  • exitatory
  • inhibitory
40
Q

what does an exitatory neurotransmitter do?

A

causes depolarisation (+) and generates an action potential

41
Q

what does an inhibitory neurotransmitter do?

A

causes hyperpolarisation (-) and prevents an action potential

42
Q

what is the space between synapses called?

A

synaptic cleft

43
Q

how are neurotransmitters transported to the presynaptic membrane?

A

in vesicles

44
Q

why do synaptic vesicles move toward the presynaptic membrane?

A

calcium channels open, causing an influx of CA ions

45
Q

what is a stimulus?

A

a sensory input from the environment

46
Q

what do cones detect?

A

colour in bright light

47
Q

what do rods detect?

A

black and white vision, sensitive to light intensity

48
Q

how many cones attach to a bipolar cell?

A

1

49
Q

how many rods attach to a bipolar cell and what does this do?

A

3, this gives a greater chance of recepting in low light

50
Q

what is rhodopsin?

A

light sensitive pigment in rods

51
Q

what is the process of splitting rhodopsin called?

A

bleached

52
Q

what does rhodopsin split into?

A
  • retinal
  • opsin
53
Q

what is glutamate?

A

an inhibitory neurotransmitter

54
Q

what is brain grey matter and where is it found?

A

neuronal cell bodies, outer part of brain

55
Q

what is brain white matter and where is it found?

A

myelinated axons, inner part of brain

56
Q

what is the cerebral cortex responsible for?

A

consciousness, intelligence, memory and language

57
Q

what is the cerebellum responsible for?

A

co-ordination and balance

58
Q

what is the medulla responsible for?

A

unconscious activities

59
Q

what is the hypothalamus responsible for?

A

controls thermoregulation

60
Q

name all 4 types of brain scan?

A
  • CT scan
  • MRI
  • FMRI
  • PET
61
Q

name 3 features of CT scans?

A
  • uses X-rays
  • denser parts absorb more radiation, so they appear lighter
  • shows structure not function
62
Q

name 3 features of an MRI?

A
  • uses magnetic fields and radio-waves
  • shows structure not function
  • clear tumor detection
63
Q

name 2 features of an FMRI?

A
  • shows location of oxygenated blood, showing activity
  • shows structure and function
64
Q

name 3 features of a PET scan?

A
  • patient is injected with radioactive glucose
  • amount of glucose detected indicates which areas are active
  • shows structure and function
65
Q

what is a critical window?

A

time periods after birth that the nervous system needs specific stimuli in order to develop properly

66
Q

what are ocular dominance columns?

A

strips of neurones in the visual cortex that respond preferentially to input from a certain eye

67
Q

what happens if the visual critical window is missed?

A

Neurones aren’t stimulated, so action potential isn’t received and synapse connections in the ocular dominance columns become weaker until they’re lost

68
Q

define habituation?

A

when an animal receives a repeated stimulus without any positive or negative outcome, it will learn not to respond

69
Q

what hormone affects depression?

A

seratonin

70
Q

what hormone affects parkinsons?

A

dopamine

71
Q

why cant dopamine be injected to treat parkinsons?

A

it cant cross the blood brain barrier

72
Q

why is leva-dopa used to treat parkinsons?

A

it can cross the blood brain barrier, where its absorbed by nerve cells and turned into dopamine

73
Q

what do SSRI’s do?

A

blocks serotonin removal from the synaptic cleft

74
Q

what is the 5-HTT gene responsible for?

A

recycling seratonin from synaptic cleft to pre-synaptic membrane

A-level Biology (6 decks)

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