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Biology A2 > 8 co-ordination in mammals > Flashcards

8 co-ordination in mammals Flashcards

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1
Q

what does the nervous system consist of?

A

the CNS, peripheral nerves and neurones

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2
Q

what are neurons?

A

cells that can carry rapid electrical impulses

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3
Q

what are Schwann cells?

A

cells that wrap around the axon

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4
Q

role of Schwann cells?

A

provide electrical insulation and protection
nerve regeneration

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5
Q

what is the myelin sheath made of?

A

Schwann cells (membranes)

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6
Q

role of the myelin sheath

A

electrical insulation
prevents generation of action potentials
faster transmissions

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7
Q

what are dendrites?

A

small extensions

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8
Q

role of dendrites

A

receives signals from neurones to cell body/area where signals are received

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9
Q

what are the nodes of ranvier?

A

gaps between the myelin sheaths

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10
Q

role of the nodes of ranvier

A

allow saltatory action(jumps between nodes)

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11
Q

role of axon

A

allows transmission across great distances

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12
Q

what is the soma?role?

A

contains nucleus and lots of RER- makes proteins and neurotransmitters

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13
Q

what neurone conducts nerve impulses from RECEPTORS to the CNS?

A

sensory neurons

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14
Q

what neurone conducts nerve impulses within the CNS?

A

relay

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15
Q

what neurone conducts nerve impulses from CNS to the effectors?

A

motor

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16
Q

what neurone has LONG dendrites and SHORT axons?

A

sensory

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17
Q

what neurone has SHORT dendrites and LONG axons? hint: MS.DLA

A

motor

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18
Q

what neurone has spider looking cell body?

A

relay

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19
Q

at rest what is the balance of K+ and Na+ ions INSIDE the membrane?

A

MORE K+ ions

less Na+ ions

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20
Q

value for resting potential?

A

-70 millivolts

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21
Q

high Na+ concentration can be maintained by a …./….. p…………. via ……………. …………….

A

Na+/K+ pump via active tranport

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22
Q

define neurotransmitter

A

hormone like substance released from pre-synaptic neurone and DIFFUSES ACROSS CLEFT to post-synaptic neurone

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23
Q

define synapse

A

junction between 2 neurones

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24
Q

what do synapses allow?

A

a single impulse to travel along a neurone to be transmitted to a number of different neurones

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25
Q

what is meant by cholinergic synapse?

A

uses ACETYLCHOLINE as its neurotransmitter

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26
Q

what is meant when a membrane is polarised?

A

there’s a difference in charge

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27
Q

order repolarisation, hyperpolarisation and depolarisation correctly

A

DE
RE
HYPE

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28
Q

what type of neurone is this?

A

sensory

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29
Q

what type of neurone is this?

A

motor

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30
Q

what type of neurone is this?

A

relay

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31
Q

what is the direction of an impulse along a motor neurone?

A

cell body -> AXON TERMINAL where the EFFECTOR cells are

32
Q

what is the direction of an impulse along a sensory neurone?

A

receptor cells -> axon terminal -> CNS

33
Q

what is the threshold for an AP to occur?

A

-55 mV

34
Q

during hyperpolaristion (3) what ion channels are open?

A

NETHER K+ or Na+

35
Q

define action potential.

A

when a stimulus triggers a rapid change in potential difference

36
Q

reorganise: depolarisation, hyperpolarisation, stimulus, resting potential, repolarisation.

A
  1. stimulus
  2. depolarisation
  3. repolarisation
  4. hyperpolarisation
  5. resting potential
37
Q

neurone cell membranes are _________ at rest.

A

polarised (difference in charge)

38
Q

how is resting potential established.(5)

A

-sodium-potassium pump transports 3Na+ OUT 2K+ IN via active transport

-chemical gradient of 3Na+ and 2K+ cause diffusion

  • K+ gates open but sodium gates shut, so K+ will diffuse out of cell DOWN conc. gradient
  • this makes the overall charge inside more negative, creating an electrical gradient
  • equilibrium is established
39
Q

what does a voltage gated channel mean?

A

only open in dependency of cell membrane potential

40
Q

what does a stimulus do?

A

excites cell and SODIUM ION CHANNELS OPEN

41
Q

describe what happens for an AP to take place.(5)

A
  • energy of stimulus causes sodium ion channels to OPEN, sodium diffuses into membrane = DEPOLARISATION
  • change to electrical gradient to - 30 passes the threshold, allowing more Na+ channels to open causing a BURST OF DIFFUSION
  • as cell membrane becomes less negative and now positive, pd of +40 mV is reached, Na+ channels CLOSE and POTASSIUM ION CHANNELS OPEN
  • no electrical gradient so more K+ open and (leave high to low) more K+ outside = REPOLARISATION
  • hyperpolarisation state reached when below -70 is reached so K+ close
  • sodium-potassium pump will restore resting potential difference
42
Q

what is the refractory period?

A

short period of time after an AP is generated, where the membrane CANNOT BE DEPOLARISED

43
Q

what is the importance of the refractory period? 3

A
  • ensures unidirectionality, forces AP down the axon
  • AP are discrete (separate)
    • limits how many can pass along axon at once
44
Q

what is a synaptic vesicle?

A

membrane bound structures containing neurotransmitter substances

45
Q

what is the synaptic cleft?

A

gap between 2 neurones

46
Q

what do neurotransmitters do?trigger?

A

diffuse across cleft and bind to specific receptors, maybe triggering:

  • AP
  • muscle contraction in muscle cell
  • hormone secretion from gland cell
47
Q

how do synapses ensure unidirectionality?

A

receptors are only found on the POST-SYNAPTIC membrane

48
Q

how do neurotransmitters transmit nerve impulses.(6)

A
  • AP arrives at synaptic knob at end of neurone, AP stimulate Ca2+ channels to open, so INFLUX OF Ca2+ by diffusion
  • influx causes the fusion of synaptic vesicle and presynaptic membrane
  • vesicles release neurotransmitter into synaptic cleft- exocytosis
  • neurotransmitter diffuses across cleft and BINDS TO SPECIFIC RECEPTORS on postsynaptic membrane
  • this causes SODIUM ION CHANNELS TO OPEN
  • INFLUX OF Na+ causes AP (if threshold is reached)
  • neurotransmitter is removed by diffusing black so its doesn’t repeat
49
Q

what is spatial summation?

A

many neurones share SAME cleft (one postsynaptic membrane) so all the neurotransmitter is enough to create an AP

50
Q

what is temporal summation?

A

a single presynaptic neurone releases neurotransmitter many times over a short period of time, total will cause AP

51
Q

what happens if an inhibitory neurotransmitter is released eg GABA?

A
  • Cl- channels will open, causing an influx of negative chloride ions making the membrane more negative making it harder for an AP to be generated
  • as the threshold is harder to reach
52
Q

inhibitory or excitatory neurones will work ___________ at the same synapse. meaning?

A
  • antagonistically
  • summation will occur resulting in either overall inhibition or excitation
53
Q

role of conjunctiva?

A

protects cornea

54
Q

role of the cornea?

A

bends light

55
Q

role of the lens ?

A

focuses light onto the retina

56
Q

role of the iris ?

A

controls amount of light entering the eye

57
Q

role of the sclera?

A

protective layer

58
Q

role of the choroid?

A

a black layer preventing internal reflection of light

59
Q

role of the retina?

A

contains light sensitive cells

60
Q

role of the blind spot ?

A

lacks light sensitive cells, where the optic nerve leaves the eye

61
Q

role of the fovea?

A

most sensitive part of the retina

62
Q

role of the ciliary muscles?

A

controls the size of the pupil

63
Q

role of the optic nerve ?

A

carries impulses

64
Q

role of the vitreous humour?

A

jelly-like substance maintaining shape of eye

65
Q

how do muscles in the iris respond to dim light.

A

radial muscles- contract

circular muscles- relax

overall = dilation

66
Q

how do muscles in the iris respond to bright light.

A

radial muscles- relax

CIRCULAR muscles- CONTRACT

overall = CONSTRICTION

67
Q

what are the two types of nervous system?

A

sympathetic and parasympathetic

68
Q

features of a sympathetic nervous system. hint:F+F

A
  • stimulates effectors speeding up activity
  • heightened warrens to cope with stressful situations
69
Q

features of a parasympathetic nervous system.

A
  • rest and digest
  • conserving energy
  • controls activities under normal resting conditions
  • INHIBITS EFFECTORS
70
Q

the hormonal system is made up of ____ and ____ and sends information as ______ _______.

A

glands and hormones

CHEMICAL SIGNALS

71
Q

rod cells contain a light-sensitive pigment called _______.

A

rhodopsin

72
Q

organise these from outer to inner. choroid layer, retina and sclera

A

OUTSIDE EYE 1-sclera

2-choroid layer

-retina

73
Q

what happens when light enters the eyed hits photoreceptors?

A
  • light is absorbed by photo-sensitive pigments
  • bleaching causes a chemical change
  • triggers a nerve impulse along a bipolar neurone, which is connected to the optic nerve that will take impulses to the brain
74
Q

rod cells allow _____ + ______ vision. cone cells allow _____.

A
  • black and white
  • COLOUR
75
Q

how does light cause a change in voltage across the cell surface membrane?5

A
  • light is absorbed by rhodopsin
  • rhodopsin changes shape and breaks apart into retinAL and opsin
  • opsin bind to the membrane causing sodium ion channels to CLOSE
  • the pump will still pump 2 sodiums out for every three potassiums in via active transport but none can diffuse back into cell
  • MORE sodium OUTSIDE- cell is hyperpolarised, very negative
  • no inhibitory neurotransmitter released so bipolar neurone is not inhibited (depolarised) and doesn’t stop AP to reach brain via the optic nerve
76
Q

what happens in rod cells when it’s dark?

A
  • Na+ is pumped out using active transport and diffuse back as channels are open
  • Inside membrane is slightly negative so depolarised
  • triggers release of neurotransmitter
  • neurotransmitter released will inhibit bipolar neurone so it cannot allow the AP to travel along optic nerve

Biology A2 (15 decks)

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