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Biology > Topic 8 > Flashcards

Topic 8 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is a stimulus?

A

any change in the internal or external environment

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2
Q

what are receptors?

A

cells or proteins on a cell surface membrane that detect a change

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3
Q

what are effectors?

A

cells that bring about a response to a stimulus, to produce an effect

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4
Q

give to examples of effectors

A

muscle cells and cells in the pancreas

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5
Q

how do receptors communicate with effectors?

A

via the nervous system or hormonal system

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6
Q

how does the nervous system send information?

A

as electrical impulses

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7
Q

what are the 3 main types of neurones?

A

sensory, motor and relay neurones

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8
Q

what is the function of a sensory neurone?

A

transmits electrical impulses from the receptors to the central nervous system

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9
Q

what is the function of a motor neurone?

A

transmits electrical impulses from the central nervous system to effectors

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10
Q

what is the function of a relay neurone?

A

transmits electrical impulses between the sensory and the motor neurones

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11
Q

what is the process of a mammal responding to dim light?

A

stimulus- dim light
receptors- photoreceptors in eyes detect lack of light
CNS- processes the information
effector- radial muscles in iris are stimulated by motor neurones
response- radial muscles contract to dilate pupils

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12
Q

what is the process of a mammal responding to bright light?

A

stimulus- bright light
receptors- photoreceptors in eyes detect bright light
CNS- processes information
effector- circular muscles in iris are stimulated by motor neurones
response- circular muscles contract to constrict pupil

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13
Q

what is the reflex arc?

A

stimulus, receptors, sensory neurone, relay neurone, motor neurone, effector (muscles/glands), response

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14
Q

what is a gland?

A

a group of cells that are specialised to secrete a useful substance, such as a hormone

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15
Q

what can stimulate a gland to secrete a hormone?

A

glands stimulated by change in concentration of specific substance (sometimes another hormone) or by electrical impulses

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16
Q

what does the hormonal system use for communication?

A

chemicals

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17
Q

what does the nervous system use for communication?

A

electrical impulses

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18
Q

which is faster, nervous or hormonal communication? Why?

A

nervous as electric impulses are fast and hormones travel at ‘speed of blood’

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19
Q

does nervous or hormonal communication have widespread response? Why?

A

hormonal has widespread response as target cells can be all over the body, nervous has localised response

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20
Q

why does hormonal communication have a long-lived response?

A

hormones aren’t broken down very quickly

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21
Q

why does nervous communication have a short-lived response?

A

neurotransmitters removed quickly

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22
Q

what type of neurones are in the brain?

A

unmyelinated neurones

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23
Q

what are the 4 types of tissues in mammals?

A

connective, epithelial, nervous, muscle

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24
Q

what are the 3 types of muscle tissue?

A

skeletal, cardiac, smooth

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25
Q

what is included in the central nervous system?

A

brain and spinal cord

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26
Q

what is included in the peripheral nervous system?

A

all neurones not in the brain and spinal cord

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27
Q

what is a nerve?

A

a bundle of neurones

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28
Q

what 2 systems make up the peripheral nervous system?

A

motor and sensory systems

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29
Q

what 2 systems make up the motor system?

A

somatic nervous system and autonomic nervous system

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30
Q

what is the somatic nervous system?

A

made of motor neurones
a single motor neurone transports impulses from CNS to effectors
voluntary movements

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31
Q

what is the autonomic nervous system?

A

regulates involuntary processes
involves multiple neurones linked with a ganglion

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32
Q

what is a ganglion?

A

a collection of neuronal bodies (core section of a neurone) found between neurones in the peripheral nervous system

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33
Q

what 2 systems make up the autonomic nervous system?

A

sympathetic (flight or flight) and parasympathetic (rest and digest)

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34
Q

what are the roles of the hypothalamus?

A

controls thermoregulation
secretes hormones which control the pituitary gland and others which control the water potential of the blood

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35
Q

what is the role of the posterior lobe of the pituitary gland?

A

secretes the hormone ADH which controls osmotic balance, blood pressure and kidney function

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36
Q

what is the role of the cerebrum?

A

2 hemispheres and 4 lobes:
frontal, parietal, occipital and temporal
decision making, sensory perception, vision and auditory information

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37
Q

what is the role of the cerebellum?

A

balance, posture and fine tuned movement

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38
Q

what is the function of the anterior lobe of the pituitary gland?

A

secrete hormones such as LH and FSH

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39
Q

what is the function of the medulla oblongata?

A

contain cardiac centre which controls heart rate

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40
Q

what are nodes of ranvier?

A

gaps between the Schwann cells in the myelin sheath

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41
Q

what are the Schwann cells?

A

cells that make up the myelin sheath

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42
Q

what are the Schwann cells made of?

A

lipids

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43
Q

where is the cell body of a motor neurone?

A

at the start of the neurone- in the CNS

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44
Q

where is the cell body of a sensory neurone?

A

in the middle of the neurone- in the PNS

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45
Q

where is the cell body of a relay neurone?

A

in the CNS

46
Q

compare the axons of a sensory and motor neurone

A

sensory- shorter motor- longer

47
Q

compare the dendrites of a sensory and motor neurone

A

sensory- longer motor- shorter

48
Q

what is a similarity between a motor and sensory neurone?

A

both are myelinated

49
Q

what is saltatory conduction?

A

the quick conduction which occurs when the neurones have a myelin sheath (the impulse ‘jumps’ from node to node)

50
Q

why are most neurones in the brain unmyelinated?

A

it would be a waste of energy for the brain to form the lipids

51
Q

what are concentrated in the nodes of ranvier?

A

sodium ion channels

52
Q

where does the depolarisation of a neurone occur?

A

at the nodes of ranvier

53
Q

how does an impulse ‘jump’ from node to node?

A

the neurone’s cytoplasm conducts enough electrical charge to depolarise the next node

54
Q

what are the 3 stages of an action potential?

A

depolarisation, repolarisation, hyperpolarisation

55
Q

what is happening at resting potential?

A

inside the cell is negative compared to the outside
resting potential is -70mv
more sodium ions outside the cell, ion pump uses active transport to move sodium ions out and creates electrochemical gradient
there is an even amount of potassium ions either side of the membrane as the membrane is permeable to potassium

56
Q

what happens during depolarisation?

A

stimulus
some voltage gated sodium ion channels open and sodium moves down electrochemical gradient (into the cell)
threshold of -55mv reached
all sodium ion channels open
potential difference reaches +40

57
Q

what happens during repolarisation?

A

sodium ion channels close and potassium voltage gated ion channels open
potassium ions diffuse down the concentration gradient and out of the cell
(as there are more potassium ions inside than outside of the cell)

58
Q

what happens during hyperpolarisation?

A

the voltage gated potassium ion channels are slow to close which creates a slight ‘overshoot’ and too many potassium ions leave the cell
potential difference reaches -90mv
sodium-potassium ion pump uses active transport (and ATP) to move 3 sodium ions out and 2 potassium ions in

59
Q

what is the refractory period?

A

the period after an action potential when the ion channels are still recovering and cannot be made to open so that section of the membrane cannot be excited again straight away

60
Q

what 2 things does the refractory period cause?

A

ensures that action potentials are unidirectional and only travel in one direction
acts as a time delay so that action potentials don’t overlap but pass as discrete (separate) impulses

61
Q

what does a bigger stimulus cause?

A

more frequent impulses

62
Q

how do local anesthetics work?

A

bind to sodium ion channels in the membrane of neurones and stops them from opening. This prevents depolarisation and therefore an action potential form occurring

63
Q

what are the stages of an impulse crossing a synapse?

A
  1. impulse triggers presynaptic membrane to depolarise
  2. voltage gaited calcium ion channels open and calcium enters the presynaptic knob
  3. vesicles containing neurotransmitter move closer to the presynaptic membrane and fuse to the presynaptic membrane
  4. through exocytosis the neurotransmitter is released into the synaptic cleft
  5. neurotransmitter diffuses across cleft and bind to specific receptors on the postsynaptic membrane
  6. this triggers depolarisation on the postsynaptic membrane
  7. sodium voltage gated ion channels open and sodium ions enter the cell
  8. action potential continues down postsynaptic membrane (if its a neurone)
  9. neurotransmitter is broken down by enzymes in the cleft or taken by reuptake into the presynaptic membrane or diffuse back to the presynaptic membrane
64
Q

what could be postsynaptic?

A

effector, neurone, muscle, gland

65
Q

what are the 2 types of light receptors?

A

rod and cones cells

66
Q

how do rod and cone cells act as transducers?

A

convert light energy into an electrical nerve impulse

67
Q

how many rod cells signal to one bipolar neurone?

A

three

68
Q

how many cone cells signal to one bipolar neurone?

A

one

69
Q

what is the name of the light sensitive pigment in rod cells?

A

rhodopsin

70
Q

what happens to rhodopsin when it is hit by light?

A

it is bleached/ broken down into opsin and trans retinal

71
Q

why are rod cells very sensitive to low light intensities?

A

rhodopsin doesn’t take much energy to be broken down so is broken down by low intensity light
summation increases the chance of the threshold being reached

72
Q

in low intensity why is the image low resolution?

A

the brain doesn’t know which rod cell the impulse has come from- only which bipolar cell

73
Q

do rod cells produce coloured or black and white images?

A

black and white

74
Q

do cone cells produce coloured or black and white images?

A

coloured

75
Q

why do cone cells only respond to high intensity light?

A

no summation so less chance of the threshold being reached
iodopsin requires high light intensity to be broken down

76
Q

what is the name of the light sensitive pigment in cone cells?

A

iodopsin

77
Q

where is the highest concentration of cone cells found?

A

in the fovea where light is directly focused by the lens

78
Q

what happens in a rod cell in the dark?

A

sodium ions diffuse in though open ion channels and are pumped out via active transport
inside is negative compared to outside- depolarised
calcium ions move into the rod cell
inhibitory neurotransmitter glutamate released
glutamate inhibits action potential in postsynaptic membrane (on bipolar cell)
no information goes to the brain

79
Q

what happens in a rod cell in the light?

A

rhodopsin hit with light
rhodopsin broken down into opsin and trans-retinal (bleaching)
opsin binds to membrane causing sodium ion channels to close
sodium ions cannot diffuse back into the cell
outside of the membrane has more sodium ions- membrane is hyperpolarised
calcium ions not triggered to open
neurotransmitter (glutamate) not released
depolarisation/action potential occurs as sodium ion channels open

80
Q

what are the 4 problems with studying the brain?

A

skull (difficult to ‘see’ through), complex interconnections, fragile, blood brain barrier

81
Q

what does CT stand for?

A

computerised tomography

82
Q

what does a CT scan use?

A

x-rays

83
Q

how do different tissues look in a CT scan?

A

denser tissue absorbs more radiation and so shows lighter

84
Q

do CT scans show structures or functions?

A

structures

85
Q

what are the advantages of a CT scan?

A

cheaper

86
Q

what are the disadvantages of a CT scan?

A

low resolution, black and white, risk of damage from radiation (although small)

87
Q

what does MRI stand for?

A

magnetic resonance imaging

88
Q

what does an MRI use?

A

radio waves and magnetic fields

89
Q

how do different tissues look in an MRI scan?

A

tumour cells show as lighter than healthy tissue

90
Q

does an MRI scan look at structure or function?

A

structure

91
Q

what are the advantages of an MRI scan?

A

higher resolution than a CT, shows exact size and location of tumour, no ionising radiation used so no risk of damage

92
Q

what are the disadvantages of an MRI scan?

A

black and white, more expensive than a CT, no people with pacemakers as no metal

93
Q

what does fMRI stand for?

A

functional magnetic resonance imaging

94
Q

what does fMRI use?

A

radio waves and magnetic fields

95
Q

how do different tissues look in an fMRI scan?

A

more oxygenated blood flows to active areas, molecules in the oxygenated blood respond differently to the magnetic field and show as lighter/coloured

96
Q

does an fMRI look at structure or function?

A

both

97
Q

what are the advantages of fMRI?

A

looks at structure and function, high resolution, coloured image

98
Q

what are the disadvantages of fMRI?

A

expensive

99
Q

what does PET stand for?

A

positron emmission tomography

100
Q

what do PET scans use?

A

radioactive tracers

101
Q

how do different tissues look in a PET scan?

A

area with high amounts of tracer show brighter/more coloured

102
Q

does a PET scan look at structure or function?

A

both

103
Q

what are the advantages of PET scans?

A

very detailed, show if areas are active or inactive

104
Q

what are the disadvantages of PET scans?

A

expensive

105
Q

how do animal experiments show nature affects brain development?

A

genetically similar rats in same environment showed different brain developments

106
Q

how do animal experiments show nurture affects brain development?

A

rats reared in isolation have similar brain abnormalities to those with schizophrenia

107
Q

how do twin studies show nature affects brain development?

A

twins have similar IQ scores

108
Q

how do twin studies show nurture affects brain development?

A

no differences in reading ability between identical and non-identical twins

109
Q

how do cross-cultural studies show nature affects brain development?

A

similarities between different cultures may be due to genetics

110
Q

how do cross-cultural studies show nurture affects brain development?

A

any differences between different cultures may be due to different upbringings

111
Q

how do brain damage studies show nature affects brain development?

A

after brain damage, if a characteristic doesn’t develop (as nurture isn’t having an effect)

112
Q

how do brain damage studies show nurture affects brain development?

A

after brain damage, if a characteristic does develop the upbringing is why the characteristic is occurring

Biology (9 decks)

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