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Biology A2 > Ch13 - neuronal communication > Flashcards

Ch13 - neuronal communication Flashcards

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1
Q

4 examples of changes to an organisms internal environment

A

blood glucose conc
internal temp
water potential
cell pH

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2
Q

4 examples of changes to an organisms external environment

A

humidity
external temp
light intensity
sound

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3
Q

what is homeostasis

A

functions of organs co-ordinated to maintain a constant internal environment

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4
Q

what is a stimulus

A

changes in the internal and external environment

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5
Q

what is the role of neurones

A

trasmit electrical impulses quickly so organism can respond to changes in env

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6
Q
A

cell body - nucelus w/ cytoplasm
dendrons - small extensions from CB -> smaller extensions denedrites
axons - cylindrical cytoplasm surrounded by plasma membrane

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7
Q

function of:
cell body

A

cell body
in cytoplasm -> lots of ER + mitochondria -> neurotransmitter production

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8
Q

function of dendrons

A

transmit signals towards cell body

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9
Q

function of axons

A

transmit impulses away from cell body

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10
Q

what is the structure + function of sensory neurones

A

transmit from sensory receptor cell -> relay/motor/brain
one dendron -> cell body -> axon

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11
Q

structure + function of relay neurones

A

transmit impulses b/w neurones
many short axons +
dendrons

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12
Q

structure + function of motor neurones

A

from relay/sensory -> effector
one long axon + many short dendrites

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13
Q

what is the usual nervous response pathway

A

receptor -> sensory N -> relay N -> motor N -> effector

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14
Q

what does a schwaan cell do

A
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15
Q

what does the myelin sheath do?

A

insulating layer
conduct impulses much faster

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16
Q

what are the gaps b/w each shwaan cell

A

nodes of ranvier
every 1-3mm

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17
Q

how do nodes of ranvier help impulses to transmit faster

A

impulse jumps from node -> node
transmitted faster than if it has to travel directly through the whole axon

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18
Q

2 main features of sensory receptors

A

specific to one type of stimulus
acts as a transducer (stimulus -> impulse)

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19
Q

pacininian corpuscle is what type of receptor
what is the stimulus
and example of sense organ

A

mechanoreceptor
pressure + movement
skin

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20
Q

olfactory receptor is what type of receptor
what is the stimulus
and example of sense organ

A

chemoreceptor
chemicals
nose

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21
Q

give an example of a thermoreceptor
what is the stimulus
ex of a sense organ

A

end-bulbs of krause
heat
toungue

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22
Q

give an example of a photoreceptor
what is the stimulus
ex of a sense organ

A

cone cell
light
eye

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23
Q

describe the structure of pacinian corpuscle

A

sensory neurone in centre
layers of connective tissue
separated by layer of gel

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24
Q

describe the steps for how pacinian corpuscle converts mechanical pressure to nervous impulse

A

1) normal state: Na+ ions too narrow | neurone has resting potential
2) pressure applied -> shape changes -> membrane streches
3) Na+ channels widen -> Na+ diffuse into neurone
4) membrane depolarised -> generator potential
5) generator potential -> action potential across sensory neurone -> CNS

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25
Q

describe the state of resting potential

A

outside membrane more +ve so potential difference
membrane is polarised
-70mV

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26
Q

Na+ are actively transported … of the axon while K+ AT … the axon

what is this process called

A

out
in

sodium-potassium pump

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27
Q

what is the ratio of Na+ and K+ moving in and out of axon

A

3 Na+ out
2 K+ in

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28
Q

what does this sodium potassium pump lead to

A

more Na+ outside and more K+ inside cytoplasm.

Na+ diffuese back through electrochemical gradient & K+ diffuse out of axon

Na+ channels are gated - Na+ dont move much, lots of K+ diffuse out

more +ve charge outside
resting potentical across membrane of -70mV (inside is -ve relative to outside)

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29
Q

breify descirbe the process of an action potential

A

energy of stimulus -> p.d changes (+40mV) = depolarisation
impulse passes -> repolarisation (+ve -> -ve)

30
Q

what are the sequence of events that take place during action potential

A

resting potential -> E from stimulus -> voltage gated Na+ channels open -> Na+ diffuse into axon -> neurone less -ve -> more Na+ (positive feedback)

+40mV p.d reached -> VG Na+ channels close -> VG K+ open
K+ diffuse out -> inside more -ve than usual -> hyperolarisation

VG K+ close -> Na & K pump -> axon repolarised to resting potential

31
Q

after the first region of axon membrane is depolarised what happens

A

process continous (wave of depolarization)
Na+ inside axon attracted by -ve charge in front -> diffuse further
K+ move out so start of axon membane is repolarised (resting potential_

32
Q

what is the refractory period and why is it important

A

when axon cant be excited again
VG Na+ channels closed
ensures propagation of action potential moves forward and doesn’t overlap

33
Q

what is saltatory conduction

A

depolarisation of axon only at nodes of ranvier
localised circuits arise b/w nodes
action potential jumps across axon

34
Q

what are the two benefits of saltatory conduction

A

quicker (less opening + closing Of ion channels)
more E effecient -> repolarisation uses ATP -> less repolarisation -> less E

35
Q

apart from myelination what two other factors effect speed of action potential

A

axon diameter -> bigger = faster -> less resistance to ion flow in cytoplasm

temperature -> high temp = quicker
only up to 40c otherwise denaturing to Na-K pump proteins

36
Q

what are the 6 key features of a synapse

A

presynaptic neurone
synaptic knob
synaptic cleft
postsynaptic neurone
synaptic vesicles
neurotransmitter receptors

37
Q

what is a neurotransmitter

A

chemicals that carry an impulse arcross a synapse

38
Q

2 types of neurotransmitters

A

excitatory
inhibitory

39
Q

what does an excitatory neurotransmitter do and give an example

A

depolarise postsynaptic neurone
if threshold reached -> action potention triggered
acetylcholine

40
Q

what does an inhinbitory neurotransmitter do and give an example

A

hyperpolarise postsynaptic membrane
prevents action potential being triggered
GABA in the brain

41
Q

what are the 8 steps of how synaptic transmission occurs

A

action potential at preS neurone

depolarises preSN | Ca2+ channels open

Ca2+ diffuse into preS knob

synaptic vesicles fuse with preSM -> neurotransmitter into cleft by exocytosis

neurotransmitters bind w/ receptors on postSM

NA+ channles open
Na+ diffuse into postSN
action potential triggered + propagated

42
Q

what happens to neurotransmitter after action potential is created

A

broken down so preventing response form happening again
products take back to preSM to be recycled

43
Q

describe the transmission across s cholinergic synapses after neurotransmitter creates action potential

A

acetylcholine hydrolysed by acetylcholinesterase -> choline + ethanoic acid

diffuse back along cleft to preSN to be recycled led
ATP released by mitochondria to recreate acetylcholine
stored in synaptic vesicles
Na+ channels close

44
Q

what 3 roles do synapses play in nervous transmission

A

ensure impulses travel in one direction

allow impulse from one neurone -> many neurones at multiple synapses

number of neurones -> same synapse

45
Q

what is summation

A

when the amount of neurotransmitter builds up enough to reach the threshold to create an action potential

46
Q

2 types of summation and briefly describe each

A

spatial - many preSN -> 1 postSN

temporal - one preSN releases many neurotransmitters over short time

47
Q

2 types of summation and briefly describe each

A

spatial - many preSN -> 1 postSN

temporal - one preSN releases many neurotransmitters over short time

48
Q

what is the 2 structural groups the nervous system is organised into

A

central nervous system - brain + spinal cord

peripheral nervous system - all the other neurones
receptor -> sensory -> CNS
CNS -> motor -> effector

49
Q

describe the functional organisation of the PNS

A

somatic: concious
autonomic: unconcious

autonomic:
sympathetic: makes things faster (heart ect)
neurotransmitter: noradrenaline
parasympathetic: resting + digesting
neurotransmitter: acetylcholine

50
Q

what are the 5 main areas of the brain

A

cerebrum
cerebellum
medulla oblongata
hypothalamus
pituitary gland

51
Q

what does the cerebrum do

A

voluntary actions
learning, memory, personality, concious thought

52
Q

what does the cerebellum do

A

unconcious thought
posture, balance, non-voluntary movement

53
Q

what does the medulla do

A

autonomic control
heart rate + breathing rate
swallowing, peristalsis + coughing

54
Q

what does the hypothalamus do

A

regulates temp + water

55
Q

what does the pituitary gland do

A

stores + releases hormones for other bodily functions

56
Q

what is a feature of the cerebrum that increases its capacity for brain activity

A

highly convoluted

57
Q

each half of the cerebrum controls one half of the body and these are called …………..
these halfs are covered by a layer called …….

reasoning + decison making occur in which part of this outer layer

A

cerebral hemispheres
cerebral cortex

frontal and prefrontal lobe of the cerebral cortex

58
Q
A

receptor cell -> sensory area in hemisphere -> association areas
impulses from motor area -> effector

59
Q

what area mainly controls movement in the cerebrum

A

primary motor cortex at the back of the frontal lobe

60
Q

what happens at the base of the brain and give an example of where this is used

A

impulses from each side cross
impulses from right eye -> visual cortex in left
helps brain judge distance and perspective

61
Q

what does the cerebellum do

how would someone with a damaged cerebellum act

A

co-ordinated movement
receives info from ear + muscles -> relays -> cerebral cortex

they would have jerky uncoordinated movement

62
Q

what are the hypothalamus 3 main functions

A

controlling complex behaviour - eating, sleeping, anger

monitoring blood plasma - rich blood supply through hypothalamus

producing hormones -> it is an endocrine gland

63
Q

how is the hypothalamus separated

A

Parasympathetic and sympathetic nervous system

64
Q

where is the pituitary gland found

A

base of hypothalamus

65
Q

What is a reflex

A

Involuntary response to a sensory stimulus

66
Q

What are the base steps most reflex arcs take

A

Receptor - detect stimuli -> action potention in SN
SN - impulse to spinal cord
RN - SN to MN in spinal or brain
MN - impulse to effector

67
Q

What is the spinal cord

A

Column of nervous tissue running up the back surrounded by spine
Neurones at intervals

68
Q

What is a spinal reflex
Give an example of one

A

Neural pathway only goes to spinal cord not brain
Knee-jerk reflex

69
Q

Describe the pathway of the knee-jerk reflex

A

Leg tapped
Patellar tendon stretched (stimulus)
Reflex arc -> extensor muscle on thigh to contract
A RN inhibits MN of flexor muscle -> relax
Co-ordination of these both causes leg to kick

70
Q

What is a cranial reflex
Give an example of one

A

Where the reflex arc goes through brain bit spinal cord
Blinking reflex

71
Q

Describe the pathway of the blinking reflex
When might doctors test this reflex

A

Cornea irritated (stimulus)
Action potential along SN -> impulse -> RN in lower brain stem -> branches of MN -> eyelids close

To test if a patient is brain dead

72
Q

Give 4 features of reflexes increase your chance of survival

A
  • involuntary - prevents overloading brain
    Not learnt - immediate protection from birth
    Extremely fast - short reflex arc
    Everyday actions - controlling balance ect

Biology A2 (2 decks)

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