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Biology A2 > Ch13 - neuronal communication > Flashcards

Ch13 - neuronal communication Flashcards

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
describe the state of resting potential
outside membrane more +ve so potential difference membrane is polarised -70mV
26
Na+ are actively transported ... of the axon while K+ AT ... the axon what is this process called
out in sodium-potassium pump
27
what is the ratio of Na+ and K+ moving in and out of axon
3 Na+ out 2 K+ in
28
what does this sodium potassium pump lead to
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)
29
breify descirbe the process of an action potential
energy of stimulus -> p.d changes (+40mV) = depolarisation impulse passes -> repolarisation (+ve -> -ve)
30
what are the sequence of events that take place during action potential
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
after the first region of axon membrane is depolarised what happens
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
what is the refractory period and why is it important
when axon cant be excited again VG Na+ channels closed ensures propagation of action potential moves forward and doesn't overlap
33
what is saltatory conduction
depolarisation of axon only at nodes of ranvier localised circuits arise b/w nodes action potential jumps across axon
34
what are the two benefits of saltatory conduction
quicker (less opening + closing Of ion channels) more E effecient -> repolarisation uses ATP -> less repolarisation -> less E
35
apart from myelination what two other factors effect speed of action potential
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
what are the 6 key features of a synapse
presynaptic neurone synaptic knob synaptic cleft postsynaptic neurone synaptic vesicles neurotransmitter receptors
37
what is a neurotransmitter
chemicals that carry an impulse arcross a synapse
38
2 types of neurotransmitters
excitatory inhibitory
39
what does an excitatory neurotransmitter do and give an example
depolarise postsynaptic neurone if threshold reached -> action potention triggered acetylcholine
40
what does an inhinbitory neurotransmitter do and give an example
hyperpolarise postsynaptic membrane prevents action potential being triggered GABA in the brain
41
what are the 8 steps of how synaptic transmission occurs
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
what happens to neurotransmitter after action potential is created
broken down so preventing response form happening again products take back to preSM to be recycled
43
describe the transmission across s cholinergic synapses after neurotransmitter creates action potential
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
what 3 roles do synapses play in nervous transmission
ensure impulses travel in one direction allow impulse from one neurone -> many neurones at multiple synapses number of neurones -> same synapse
45
what is summation
when the amount of neurotransmitter builds up enough to reach the threshold to create an action potential
46
2 types of summation and briefly describe each
spatial - many preSN -> 1 postSN temporal - one preSN releases many neurotransmitters over short time
47
2 types of summation and briefly describe each
spatial - many preSN -> 1 postSN temporal - one preSN releases many neurotransmitters over short time
48
what is the 2 structural groups the nervous system is organised into
central nervous system - brain + spinal cord peripheral nervous system - all the other neurones receptor -> sensory -> CNS CNS -> motor -> effector
49
describe the functional organisation of the PNS
somatic: concious autonomic: unconcious autonomic: sympathetic: makes things faster (heart ect) neurotransmitter: noradrenaline parasympathetic: resting + digesting neurotransmitter: acetylcholine
50
what are the 5 main areas of the brain
cerebrum cerebellum medulla oblongata hypothalamus pituitary gland
51
what does the cerebrum do
voluntary actions learning, memory, personality, concious thought
52
what does the cerebellum do
unconcious thought posture, balance, non-voluntary movement
53
what does the medulla do
autonomic control heart rate + breathing rate swallowing, peristalsis + coughing
54
what does the hypothalamus do
regulates temp + water
55
what does the pituitary gland do
stores + releases hormones for other bodily functions
56
what is a feature of the cerebrum that increases its capacity for brain activity
highly convoluted
57
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
cerebral hemispheres cerebral cortex frontal and prefrontal lobe of the cerebral cortex
58
receptor cell -> sensory area in hemisphere -> association areas impulses from motor area -> effector
59
what area mainly controls movement in the cerebrum
primary motor cortex at the back of the frontal lobe
60
what happens at the base of the brain and give an example of where this is used
impulses from each side cross impulses from right eye -> visual cortex in left helps brain judge distance and perspective
61
what does the cerebellum do how would someone with a damaged cerebellum act
co-ordinated movement receives info from ear + muscles -> relays -> cerebral cortex they would have jerky uncoordinated movement
62
what are the hypothalamus 3 main functions
controlling complex behaviour - eating, sleeping, anger monitoring blood plasma - rich blood supply through hypothalamus producing hormones -> it is an endocrine gland
63
how is the hypothalamus separated
Parasympathetic and sympathetic nervous system
64
where is the pituitary gland found
base of hypothalamus
65
What is a reflex
Involuntary response to a sensory stimulus
66
What are the base steps most reflex arcs take
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
What is the spinal cord
Column of nervous tissue running up the back surrounded by spine Neurones at intervals
68
What is a spinal reflex Give an example of one
Neural pathway only goes to spinal cord not brain Knee-jerk reflex
69
Describe the pathway of the knee-jerk reflex
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
What is a cranial reflex Give an example of one
Where the reflex arc goes through brain bit spinal cord Blinking reflex
71
Describe the pathway of the blinking reflex When might doctors test this reflex
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
Give 4 features of reflexes increase your chance of survival
* 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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