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Biology > Chapter 13- Neuronal Communication > Flashcards

Chapter 13- Neuronal Communication Flashcards

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1
Q

How sensory neurone and motor neurone are similar?

A

Both have

  • dendrites
  • an axon
  • a cell body with nucleus
  • myelin sheath covered with Schwann cells
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2
Q

Effect sweating will have on body?

A
  • evaporation will decrease body temperature

- heat is taken from the body and used for evaporation

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3
Q

Why shivering during fever when normal body temp increases?

A
  • the new ‘normal’ body temp has increased

- the body is using shivering to raise the temp of the internal environment

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4
Q

Explain vasodilation?

A
  • results in more blood nearer to the skin surface

- will lose heat + body temp will decrease

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5
Q

Why pacinian corpuscle acts as a transducer?

A

-converts mechanical energy into electrical energy

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6
Q

Why does deformation of plasma membrane cause tip of neurone become more permeable to Na+?

A

-causes Na+ channels to open

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7
Q

All or nothing law?

A

-if stimulus is strong enough, threshold value reached and AP generated

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8
Q

How strength and intensity of stimulus is connected to the brain?

A

-high frequency of action potentials shows strong impulse

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9
Q

Clothes are first put on. Constant gentle pressure applied. After a short time, action potentials are no longer generated unless there is a change in pressure. Why?

A

-na+ channels remain open so resting potential is not reestablished

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10
Q

Role of synapses?

A
  • Allow neurones to communicate
  • ensure transmission in one direction only
  • allows impulses from more than 1 neurone to be passed to a single neurone
  • allows impulses from a single neurone to be passed to more than one neurone
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11
Q

Gap in neurones?

A

Node of Ranvier

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12
Q

Explain difference in speed of conduction of action potential along myelinated and non myelinated neurone?

A
  • conduction faster in myelinated. Action potential can only occur where the VG Na+ channels are present
  • ion movement can only take place at the gaps
  • so saltatory conduction happens which is the action potential jumps from node to node
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13
Q

How acetylcholine is secreted?

A

Exocytosis

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14
Q

Part of neurone acetylcholine is secreted?

A

Synaptic knob

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15
Q

The effect that proteases may have on snare proteins?

A
  • protease may hydrolyse the peptide bonds in snare proteins
  • vesicles cannot fuse with CM + acetylcholine not secreted
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16
Q

Part of neurone where transmission of impulses is interfered?

A
  • post synaptic membrane. Prevents attachment of neurotransmitters to its receptor
  • pre synaptic knob. Prevents release of neurotransmitter or influx of Ca2+ ions
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17
Q

How resting potential established and maintained?

A
  • sodium potassium pump uses ATP to actively move 3 Na+ out and 2K+ in neurone
  • K+ ions diffuse out of leaky K channels
  • fewer Na+ channels open
  • VG Na+ channels closed
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18
Q

Order of polarisation?

A

Depolarisation
Repolarisation
Hyperpolarisation

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19
Q

What is -55mV?

A

Threshold potential

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20
Q

Relationship between strength of stimulus and resulting action potential?

A
  • only stimuli that reach threshold potential will produce action potential
  • when stimulated, action potential either occurs or not . All or nothing principle
  • action potential is same size no matter how strong stimulus is
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21
Q

Gap between two neurones?

A

Synaptic cleft

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22
Q

How first neurone communicates with second neurone?

A
  • neurotransmitter released from pre synaptic membrane
  • diffuses across synaptic cleft
  • attaches to receptors on post synaptic membrane
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23
Q

Importance of synaptic cleft?

A
  • ensures movement of action potential is one direction only
  • allows summation
  • ensures that only stimulation that is strong enough will be passed on
24
Q

Hormone that increases metabolic rate and so generates heat?

A

Adrenaline

25
Q

Action potentials all have the same?

A

Magnitude

26
Q

Function of Schwann cells?

A
  • Schwann cells produce myelin sheath
  • acts as an electrical insulator
  • prevents depolarisation
  • speeds up transmission of action potential as impulses jump from node to node. Saltatory conduction
27
Q

How acetylcholine travels across synaptic cleft?

A

Diffusion

28
Q

How synapses ensure transmission is only one direction?

A
  • only pre synaptic neurone releases acetylcholine
  • only pre synaptic neurone has Ca2+ channels
  • only post synaptic membrane has receptors
29
Q

Atropine similar shape to acetylcholine. How this prevents initiation of action potential?

A
  • atropine competes with acetylcholine for receptor on post synaptic membrane
  • prevents ACh binding
  • na+ channels remain closed
  • insufficient depolarisation is does not reach threshold potential
30
Q

Why x is described as auto immune condition?

A
  • attacked by body’s own immune system

- immune system recognises body cells as foreign

31
Q

Why damage to some myelin sheath leads to loss of sensation?

A

-stops Saltatory conduction

-

32
Q

Why increase in temp results in increased speed of conduction?

A

-more KE so ions diffuse across nodes quicker

33
Q

What would happen if temp increased too much?

A

Channels and pumps denatured

34
Q

What happens after action potential arrives at synaptic knob?

A
  • calcium channels open
  • Ca2+ ions diffuse in
  • acetylcholine in vesicles
  • vesicles move towards pre synaptic membrane
  • vesicles fuse with membrane
  • neurotransmitters released by exocytosis into synaptic cleft
35
Q

Specialised cells in nose and tongue detect what stimuli?

A

Chemical

36
Q

Where do sensory neurones transmit their impulses?

A

CNS

37
Q

Where do motor neurones transmit impulses?

A

To effectors

38
Q

How body detects that your finger has touched a pin?

A
  • touching pin exerts mechanical pressure on skin
  • pacinian corpuscle found within skin detects pressure
  • pressure changes shape of pacinian corpuscle
  • stretch mediated sodium channel in neurone membrane stretches. Channels widen
  • Na+ ions diffuse into membrane
  • generator potential created
  • generator potential creates an action potential
  • action potential transmitted along neurones to CNS
39
Q

Hyperpolarisation?

A

When potential difference is lower than the resting potential

40
Q

What would happen if refractory period didn’t exist?

A

-axon could be immediately depolarised after an action potential so action potential could travel in both directions

41
Q

What would happen if VG Na+ channels couldn’t open?

A
  • Na+ cannot enter
  • prevents depolarisation of membrane
  • prevents action potential being generated
  • no release of neurotransmitter
42
Q

Why non myelinated neurone transmits impulses more slowly?

A
  • no nodes of Ranvier

- whole axon needs to be depolarised

43
Q

CNS?

A
  • brain and spinal cord only

- has coordinating role

44
Q

PNS?

A
  • role in sensing stimuli
  • conduct impulses to and from CNS
  • includes somatic/ autonomic/ sympathetic / parasympathetic
45
Q

Describe function of Schwann cells?

A
  • Schwann cells produce myelins sheath
  • electrical insulator
  • prevents depolarisation
  • action potentials only occur at nodes of Ranvier
  • impulse jumps from node to node. saltatory conduction
  • speeds up transmission of impulses
46
Q

Neurotransmitter for sympathetic NS?

A

noradrenaline

47
Q

neurotransmitter for paraysmpathetic NS?

A

acetylcholine

48
Q

events that occur after adrenaline reaches CMS?

A
  • adrenaline binds to receptor in a complementry fit
  • adenyl cyclase activated
  • ATP convert to cAMP
  • cAMP activates enzymes by altering 3D structure and phosphorylation
49
Q

How having no. of steps in signalling pathway enables small no. of adrenalije to cause large effects?

A
  • 1 molecule causes activation of many others
  • e.g. 1 adrenaline -> many cAMP molecules
  • this multiplying step is repated at every step
50
Q

Which type of molecule can pass directly through CSM?

A

-Lipid soluble

51
Q

Where acetylycholine receptors are found?

A

post synaptic membrane

52
Q

Where is acetylcholinesterase found?

A

synaptic cleft

53
Q

Sympathetic NS?

A
  • short preganglionic neurone
  • long post ganglionic neurone
  • neurotransmitter: noradrenaline
  • fight or flight
54
Q

Parasympathetic NS?

A
  • long pre ganglionic neurone
  • short post ganglionic neurone
  • neurotransmitter: acetylcholine
  • rest or digest
  • more blood flows to smooth muscle
55
Q

Explain the difference in the speed of conduction of an action potential along myelinated and non-myelinated neurone.

A
  • conduction faster in myelinated
  • a.p. can only occur where the V.G NA+ channels are
  • in myelinated: nodes of ranvier
  • in non: total length of neurone
  • myelinated have longer sections with no V.G Na+ channels present
  • ion movement can only take place at gaps so a.p jumps from node to node/ saltatory conduction
56
Q

How nervous system decreases heart rate?

A

-impulses along the vagus nerve in parasympathetic NS

Biology (26 decks)

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