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AL. AQA Biology > stimulus + response > Flashcards

stimulus + response Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

stimulus

A

change in internal or external environment

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2
Q

receptor

A

a specific cell which detects change

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3
Q

coordinator

A

normally CNS - can also be a gland/organ - processes information from receptors

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4
Q

effector

A

usually muscle or gland - br

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5
Q

taxis

A

move towards or away from a stimulus (directional stimuli, directional movement)

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6
Q

kinesis

A

keeping moving in unfavourable conditions to remove itself from such conditions - non directional stimuli

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7
Q

myogenic

A

contracts without stimulation from brain

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8
Q

autonomic nervous system

A

controls involuntary responses

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9
Q

somatic nervous system

A

controls voluntary movements

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10
Q

peripheral nervous system made of

A

motor neurone

sensory neurone

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11
Q

2 divisions of autonomic nervous system

A

sympathetic

parasympathetic

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12
Q

how is heart rate controlled whilst exercising

A
  • increase CO2 decreases pH of blood as it forms carbonic acid
  • chemoreceptors in aorta detect drop in pH
  • send impulse to medulla oblongata via sensory neurone
  • frequency of impulses sent to SAN via sympathetic nervous system increase
  • heart rate increases
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13
Q

dendron

A

part of nerve cell leading towards cell body

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14
Q

axon

A

part of nerve cell leading away from cell body

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15
Q

Schwann cells - function

- how does it carry out function

A

insulation, making impulses faster

as contains lots of lipid myelin, as it grows its wraps cell membrane around nerve cell

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16
Q

gap between Schwann cells

A

node of ranvier

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17
Q

how is a resting potential in a neurone established?

A
  • sodium potassium ion pump pumps 3 sodium ions out of the cell for every 2 potassium ions it pumps in
  • using energy from hydrolysis of ATP to ADP + Pi
  • as sodium ion channels are closed, a resting potential is created
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18
Q

resting potential value

A

-70mv

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19
Q

refractory period

A

period after an action potential where no other action potentials can occur

20
Q

How is action potential established/reached

A
  • Na+ ions diffuse rapidly into cell through open voltage gates sodium channels
  • if value is above threshold value, rapid depolarisation of the axon will occur as all the voltage gated sodium ion channels open
21
Q

How Is resting potential established after an action potential?

A
  • Na+ voltage gated channels close, reducing membrane permeability to Na+
  • K+ channels open, allowing H+ ions to renter cell
  • depolarising the membrane
  • allowing repolarisation of the axon
  • leading to hyper polarisation until Na+K+ pump resets resting potential
22
Q

period where membrane potential is lower then resting potential

A

hyperpolarisation

23
Q

d. resting membrane potential

A

difference in charge between interior and exterior of cell

24
Q

action potential

A

moving depolarisation along the cell

25
Q

reason action potential occurs (2)

A
  • all Na+ channels closed

- resting potential not yet established

26
Q

function of refractory period (2)

A
  • ensures impulses travel in ONE direction along the axon

- produces discrete and separate action potentials - allows frequency to be detected

27
Q

difference between myelinated cells and non-myelinated cells

A
  • myelinated cells: action potentials jump from node of to node - meaning depolarisation only occurs at nodes of ranvier - via SALTATORY CONDUCTION - and not all the way along the cell = faster impulse
  • sodium ion channels concentrated at nodes
28
Q

pressure sensory =

A

Pacinian corpuscle

29
Q

how are action potentials in Pacinian corpuscle initiated

A
  • same but membrane of neurone is stretched, causing Na+ channels to open
30
Q

3 factors affecting speed of conduction of action potentials

A
  • myelination -
  • axon diameter - less resistance to ion flow = depolarisation reaches other parts of the cell faster
  • temp - as ions diffuse faster - past 40 degrees proteins denature
31
Q

pressure sensing receptors

A

baroreceptors

32
Q

where are….
- baroreceptors
- chemoreceptors
found?

A
  • artery walls - carotid artery wall

- wall of aorta, wall of carotid artery

33
Q

describe the process of a action potential being transmitted across a synapse

A
  • AP arrives at pre-synaptic terminal
  • causing voltage gated calcium ion channels to open
  • diffusion of Ca2+ into neurone
  • Ca2+ causes vesicles containing neurotransmitter (acetylcholine) to fuse with pre-synaptic membrane
  • acetylcholine released into synaptic cleft
  • diffuses across synaptic cleft
  • binds to complimentary neuroreceptor
  • if threshold value reached = rapid depolarisation of post synaptic neurone
  • acetylcholine-esterase released into synaptic cleft
  • hydrolysis of Ash into acetyl and choline (preventing continual depolarisation of axon)
  • products diffuse back across the cleft and into knob
  • hydrolysis of ATP provides energy for recombination of acetyl and choline -> acetylcholine
  • back into vesicles ready for another AP
34
Q

2 ways of reaching an AP

A
  • spatial summation

- temporal summation

35
Q

spacial summation

A

multiple synapses stimulated - combined effect of both APs

36
Q

temporal summation

A

high frequency AP = high amounts of neurotransmitter - frequency of APs is determining factors

37
Q

inhibitory synapses

A

ones which make it less likely for an AP to occur in the post synaptic neurone

38
Q

how does an inhibitory synapse work

A
  • presynaptic neurone released neurotransmitter that binds to chloride ion protein channels on post synaptic membrane
  • causing them to open
  • Cl- move into post synaptic membrane by facilitated diffusion
  • binding of transmitter caused opening of nearby K+ protein channels
  • K+ out of post synaptic neurone into synapse
    ∴ potential difference is more negative
    ∴ hyperpolarisation - less likely a new AP produced as more Na+ needed to meet threshold value
39
Q

function of choroid layer of eye

A

stops light bouncing around - absorbs

40
Q

resting potential value

A

70mv

41
Q

features of RODS (3)

A
  • cant distinguish between wavelengths of light - vision in low light intensities in B&W
  • more numerous then cones
  • multiple joined to a single bipolar neurone
    • therefore achieve generator potential by RETINAL CONVERGENCE - SUMMATION increases change of threshold value being reached
42
Q

how is a generator potential reached?

A

pigment is broken down by certain wavelengths of light

43
Q

why is there low visual acuity with rods

A
  • multiple joined to one bipolar cell (one sensory neurone) brain received one message for many rods stimulated - cut distinguish between 2 discrete items due to retinal convergence
44
Q

features of CONES (2)

A
  • each cone joined to its own bipolar neurone
  • high visual acuity as each cone is connected to a single bipolar neurone therefore brain received separate impulses as no summation and can distinguish between 2 discrete items
45
Q

greater conc of cones at…

A

fovea

AL. AQA Biology (18 decks)

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