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biology - module 5 & 6 > chapter 13 - neuronal communication > Flashcards

chapter 13 - neuronal communication Flashcards

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1
Q

What are three characteristics of nervous communication?

A
  • fast
  • short lived
  • localised
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2
Q

What does the nervous system(NS) breakdown into?

Hint - think about the tree diagram

A
  • NS breaks down into the peripheral NS and central NS
  • The peripheral NS breaks down into the somatic NS and autonomic NS
  • The autonomic NS breaks down into the parasympathetic NS and sympathetic NS
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3
Q

What is the difference between the peripheral NS and the central NS

A
  • central NS consists of the brain and spinal cord
  • peripheral NS consists of all other neurones
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4
Q

What is the difference between the autonomic NS and the somatic NS?

A
  • Autonomic NS controls unconscious control(heart rate)
  • Somatic NS controls conscious control (bicep curl)
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5
Q

What is the difference between the parasympathetic NS and the sympathetic NS?

A
  • parasympathetic NS slows things down using a neurotransmitter called acetylcholine (slows heart rate down)
  • sympathetic NS speeds things up using a neurotransmitter called noradrenaline (increasing heart rate)
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6
Q

What pathway does a nervous impulse follow?

A
  • receptor
  • sensory neurone
  • relay neurone
  • motor neurone
  • effector
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7
Q

What does the sensory neurone consist of?

A
  • A single long dendron
  • A single long axon
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8
Q

What does the relay neurone consist of and where is it located?

A
  • many short dendrites
  • many short axons
  • located in the CNS
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9
Q

What does the motor neurone consist of?

A
  • many short dendrite
  • single long axon
  • ends with a neuromuscular junction
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10
Q

What is meant by resting potential ?

A
  • There are more positive ions outside the membrane then inside
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11
Q

What is happening at the membrane during resting potential?

A
  • At the sodium potassium pump , 3 Na ions are pumped out and 2 K ions in
  • At the voltage gated sodium ion channels, they are closed and membrane is not permeable to Na
  • At the potassium ion channel, its open and some K diffuses out down the electrochemical gradient, but does not reach equilibrium because of the positive charge outside
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12
Q

What are the stages of an action potential?

A

1 - resting potential
2 - generator potential
3 - threshold
4 - depolarisation
5 - repolarisation
6 - hyperpolarisation

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13
Q

What is happening at the membrane during generator potential stage of an action potential?

A
  • weak stimulus
  • some voltage gated Na channels open and some Na ions diffuse in
  • does not reach threshold
  • Na and K pump restores resting potential
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14
Q

What is happens when threshold is reached?

A
  • Many voltage gated Na channels open and sodium diffuses into the axon
  • This is a positive feedback
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15
Q

what happens at the membrane during depolarisation stage of an action potential?

A
  • voltage gated Na channels are open and so Na diffuses in
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16
Q

What happens at the membrane during the repolarisation stage of an action potential?

A
  • Voltage gated K channels open and K diffuses out
  • voltage gated Na channels close
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17
Q

What happens during the hyperpolarisation stage of an action potential?

A
  • the membrane potential is more negative than the resting potential as the K channels are slow to close
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18
Q

What is the refractory period and why are they useful?

A
  • its the period between repolarisation and hyperpolarisation
  • during this period an action potential cannot be started
  • ensures action potentials are discrete(do not overlap) and unidirectional
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19
Q

What is depolarisation?

A
  • a process during an action potential where the membrane potential of a neurone becomes more positive than its resting state
  • this change in membrane potential occurs as the voltage gated Na channels open allowing an influx of Na ions
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20
Q

What is behind and ahead of the depolarisation phase of an action potential?

A
  • behind is the refractory period
  • ahead is the resting potential
21
Q

what does the propagation of a nerve impulse involve ?

A
  • sodium ions enter a neurone and depolarise it
  • the sodium ions diffuse further along the neurone
  • the increased positive charge caused by the diffusion of sodium ions open more voltage gated sodium ion channels
  • the action potential passes along the neurone
22
Q

what factors increase the speed of a nerve impulse?

A
  • a greater axon diameter
  • a higher temperature
  • the presence of myelin sheath
23
Q

What is salatory conduction and what is the purpose of it?

A
  • its where an action potential jumps between the nodes of ranvier
  • it speeds up the transmission of nerve impulses
24
Q

What produces myelin?

A
  • schwann cells
24
Q

Along a neurone, where can depolarisation only occur?

A
  • at the nodes of ranvier
25
Q

What is the pacinian corpuscle?

A
  • receptors that detect pressure, touch and vibrations in the skin
26
Q

What happens when the pacinian corpuscle is stimulated?

A
  • pressure causes the lamellae to stretch and deform
  • stretch mediated Na ion channels open allowing Na to diffuse into the membrane
  • The greater the stimulus the more Na ion channels open
27
Q

What is synaptic divergence and what is the purpose of it?

A
  • when one neurone joins many neurones
  • its purpose is to spread the action potential to multiple parts of the body
28
Q

What is synaptic convergence and what is the purpose of it ?

A
  • its where multiple neurones join one neurone
  • the purpose is to amplify the signal
29
Q

What is the difference between spatial and temporal summation?

A
  • temporal : where the action potentials from a single presynaptic neurone add up overtime
  • spatial : the action potentials are added together from multiple presynaptic neurones
30
Q

What is a synapse and what happens here?

A
  • its a junction between neurones
  • a chemical transmission by neurotransmitters
31
Q

How is an action potential passed along the cholinergic synapse?

A
  • action potential arrives at the presynaptic neurone
  • voltage gated Ca ion channels open and Ca ions diffuse in
  • vesicles containing acetylcholine(Ach - neurotransmitter)fuse with the presyanptic membrane
  • Ach diffuses across the synaptic cleft
  • Ach binds with the receptors on the post synaptic membrane
  • some Na channels open and Na diffuses in
  • voltage gated Na channels open
  • an action potential is triggered in the post synaptic membrane
  • acetylcholinesterase(enzyme) breaks down Ach and stops the response
  • the product of this breakdown is reabsorbed back into the presynaptic knob and recycled
32
Q

What are the advantages of a reflexes?

A
  • helps organism avoid damage
  • very fast
  • does not need to be learned(protects infants)
33
Q

explain how the nerve impulse travels in the knee jerk reflex?

A
  • stretch receptors detect a stretch
  • nerve impulse moves along the sensory neurone
  • then along the motor neurone
  • and then to the effector producing a response
34
Q

what are the different parts of the brain and what are their functions?

A
  • cerebrum: coordinates voluntary responses
  • hypothalamus: autonomic functions(thermoregulation)
  • medulla oblongata: autonomic functions (heart and breathing rates)
  • pituitary gland: releases hormones and stimulates other glands
  • cerebellum: controls balance and posture and also controls muscle contraction
35
Q

explain the structure of the voluntary (skeletal) muscle

A
  • is striated(bands of actin and myosin)
  • long cylindrical cells
  • multinucleate
  • lots of mitochondria
36
Q

what are the functions of the skeletal muscle ?

A
  • fast twitch(bicep curl) and slow twitch (posture)
37
Q

Explain the structure of the involuntary muscle

A
  • thin cells
  • uninucleate
  • slow twitch
38
Q

What are the functions of the involuntary muscle?

A
  • control diameter of blood vessels(vasodilation and vasoconstriction)
  • control of pupil size
  • peristalsis(digestive muscles contract and relax)
39
Q

Explain the structure of the cardiac muscle

A
  • branched muscle fibres
  • uninucleate
  • muscle fibres connected by intercelated discs
  • some striations
40
Q

What are the functions of the cardiac muscle?

A
  • pumps blood
  • myogenic, meaning it contracts on its own and does not require a nerve impulse
41
Q

What are muscle fibres made of?

A
  • muscle fibres are made up of myofibrils
  • myofibrils contain myofilaments (actin and myosin)
42
Q

what does the microscopic structure of a skeletal muscle consist of ?

A
  • H zone
  • dark bank (A)(consists of myosin)
  • light band(I) (consists of actin)
  • sarcomere
  • m line
  • z line
43
Q

What happens to the structure of the skeletal muscle during a contraction?

A
  • sarcomere gets shorter
  • H zone gets shorter
  • light band gets shorter
  • dark band stays the same
44
Q

What is a neuromuscular junction?

A
  • its a synapse between a neurone and a muscle fibre
45
Q

why is a neuromuscular junction different to a cholinergic synapse?

A
  • Acetylcholinesterase is found in pits on the post synaptic membrane
  • There is more receptors on the post synaptic membrane meaning an action potential is always generated in the post synaptic membrane
46
Q

Explain the sliding filament model

A
  • The sarcolemma is depolarised which spreads through the t-tubules and into the sarcoplasmic reticulum
  • Sarcoplasmic reticulum releases Ca ions
  • Ca binds to troponin changing its shape causing tropomyosin to move away from the binding site
  • Myosin heads bind to the binding sites on the actin forming cross bridges
  • Myosin heads tilt, thereby moving the actin (power stroke)
  • ATP binds to myosin, causing it to detach from the actin
  • ATP is hydrolysed to ADP causing the myosin head to resume its original position (head is free to attach further down)
47
Q

What is ATP used for in the contraction of muscles?

A
  • Changing the shape of the myosin head
  • detaches the myosin head
  • returns the myosin head to its resting position
  • reabsorb Ca ions into sarcoplasmic reticulum by active transport

biology - module 5 & 6 (12 decks)

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