neurophysiology Flashcards
(102 cards)
1
Q
Sketch the basic nervous system pathway from input to output.
A
neuron picture
2
Q
What are the roles of the nervous system?
A
control behaviour and coordinate homeostatic mechanism :
- collect info from internal & external environments.
- analyse and integrate this info.
distribute info to appropriate parts of the body.
-control muscles.
store and retrieve (when required) info.
3
Q
What are the 2 types of cells in the NS? What are their roles?
A
- vegetative (glial cells): support/protection, nutritive, developmental role (possibly processing)
- information processing (neurons): conduct info (sometimes large distances). communicate with each other and with other cell types by chemical messenger.
4
Q
What is the cell body called? What does it contain?
A
- soma
- nucleus, ER, Ribosomes for protein synthesis.
5
Q
What is the input to a neuron? How do they conduct?
A
- dendrites.
- passively conduct - signal lost over distance.
6
Q
Sketch a neuron
A
dendrites - cell body - axon - synaptic terminals.
7
Q
What is passive conduction?
A
- depolarisation in the membrane spreads across membrane and decreases in strength over distance.
- only effects voltage gated Na/K channels adjacent to the area of depolarisation.
8
Q
What type of conduction occurs on the axon?
A
- ‘internal’ active conduction.
9
Q
Where does the axon terminate?
A
- secretory endings (synapse).
10
Q
How many cells does a typical cell “talk to”?
A
- 50 other cells.
11
Q
What is the function of a sensory neuron?
A
- detect stimuli and respond by sending message into NS.
12
Q
What is the function of an interneuron?
A
- cells connecting only to other neurons within NS.
13
Q
What is the function of a motor neuron?
A
- send message out of NS to effectors (muscle/glands).
14
Q
What part of the brain is characteristic of learning?
A
- interneurons.
15
Q
What makes up the PNS?
A
- Autonomic nervous system:
- The part of the nervous system that regulates the involuntary activity of the heart, intestines, and glands, including digestion, respiration, perspiration, metabolism, and blood-pressure modulation.
- Somatic nervous system:
- The part of the peripheral nervous system that transmits signals from the central nervous system to skeletal muscle and from receptors of external stimuli to the central nervous system, thereby mediating sight, hearing, and touch.
16
Q
What makes up the ANS? What do they control?
A
- sympathetic division.
- parasympathetic division.
- enteric division.
- control of smooth muscles, cardiac muscles, glands.
17
Q
How is a message communicated within a cell?
A
- info passed over long distances as electrical impulses (action potentials) in the cell membrane.
18
Q
How is a message communicated between cells?
A
- info passed by chemical messengers (neurotransmitters).
19
Q
What is the word used to describe the ability of a cell to respond to an electrical stimulus?
A
- membranes of neurons (and muscles) are excitable.
20
Q
What must a depolarisation meet to cause an action potential?
A
- Threshold value.
21
Q
What speed does a nerve impulse travel at?
A
- 100m/s.
22
Q
What part of the cell generates an action potential?
A
generated actively (requires energy) by membrane.
23
Q
What is the name of a junction between nerve cells?
A
- synapse.
24
Q
How do cells in the NS generate electrical potentials and use them to transmit information?
A
- stimulus causes local depolarisation of membrane allowing Na flow in.
- if stimulus strong enough - enough Na flow in to reach threshold value.
- if reached Na/K voltage gated channels will open allowing flood of Na across membrane generating an action potential.
- moves unidirectionally down neuron membrane via saltatory conduction.
- unidirectional due to refractory period when sodium channels are closed and unable to open while K flows out of the neuron.
25
How do cell in the NS talk to each other across a gap?
release of neurotransmitters across synapse.
26
How does an electrical signal get converted to movement by a muscle cell?
- AP moves along sarcolemma of the muscle and down into T-tubule to the interim of the muscle near the ends of the sarcoplasmic reticulum.
- depolarisation along membrane of T-tubule leads to opening of voltage gated Ca ion channels, leading to an influx of Ca into SR.
- Ca ions then diffuse into sarcoplasm to where tropomyosin lay either side of the Actin myofilament thus covering up sites where myosin can bind.
- when the Ca ions bind to the troponin, attached to the tropomyosin, it causes a conformational change in troponin which moves the tropomyosin away from the myosin binding sites on the actin myofilaments allowing cross bridges to form.
- ADP + P on myosin head still present from last contraction allows cross bridge t form which removes P.
- energy in myosin then pulls myosin head thus moving the Actin.
- the ADP is then released and a new ATP binds to the myosin head causing it to release the actin filament.
27
What is excitability?
| What does this enable?
.
28
What are the 2 types of conduction? What are their roles?
.
29
What 2 things enable cells to make voltages?
.
30
What is the typical ratio of Na inside to outside the cell?K?Ca?Cl?
.
31
What gives a cell selective permeability?
.
32
What determines a membranes permeability?
.
33
Take K, for example, what are the 2 forces acting on K at a resting cell?
.
34
What is an equilibrium potential? What 2 things are equal at this potential?
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35
What equation is used to work out a cell’s membrane potential? Write it out
.
36
What is Ek? Describe and number? Ena? Ecl? Eca?
.
37
What ion is the cell most permeable at resting?
.
38
The membrane potential is very similar to K, why does it diverge at low K concentrations?
.
39
Which of these statements are true: because of the activity of the NA K ATPase:
a. NAi is low compared to Nao
b. Ki is low compared to Ko
c. Nai is high compared to Nao
d. Ki is high compared to Ko
.
40
Ki is high compared to Ko so when the membrane is permeable to K, this causes
a. K+ to leave the cell
b. K+ to enter the cell
c. The cell to be negative inside
d. The cell to be + inside
.
41
Though K+ leaves the cell, Ki does not fall to the level of Ko because
a. It moves very slowly
b. Na+ goes the other way
c. The cell becomes –ve inside
d. The cell becomes positive inside
.
42
What channel is responsible for depolarisation in an AP?
| This is an example of ___________ feedback. Draw this feedback loop
.
43
In a resting neuron, which channels are open?
a. Na+ selective
b. Ca2+
c. K+
d. Non selective
.
44
Describe what causes termination of the action potential
.
45
What is the role of K+ channels
.
46
Draw an AP and label when different channels open and close
.
47
Draw an AP against a voltage scale and draw the different ions and their associated voltages with channels opening
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48
During the rising phase of the AP, the membrane is highly permeable to which ion?
.
49
During the falling phase of the AP, the membrane is highly permeable to which ion?
.
50
What prevents backward spread of an action potential?
.
51
How does an action potential travel down an axon?
.
52
Which parts of the nerve conducti actively and which passively?
.
53
What is the role of myelin?
.
54
What are myelin containing cells called in the PNS?
.
55
What are the gaps between different myelin cells called?
.
56
Do action potentials vary in size?
.
57
Where does integration occur?
.
58
What is an electrical synapse? What type of cell junction enables conduction?
.
59
How does the speed of this compare to a chemical synapse?
.
60
What is the disadvantage of an electrical synapse compared to chemical?
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61
Sketch an electrical and a chemical synapse and highlight the differences
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62
Describe the steps from an AP reaching the presyn terminal to an AP in the post syn terminal
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63
What term is used to describe the way transmitter is released from as a consequence of the arriving AP in the presynaptic terminal
.
64
What channels are opened in the terminal membrane?
What are the Cao and Cai concentrations? (maybe just learn scale of differce)
What drives the Ca flux rate?
What is the Nernst potential for Ca
When do Ca channels close again?
.
65
Where is transmitter stored?
How is it transmitter secreted?
What does transmitter bind to?
What effects can the transmitter have on the postsyn memb? Describe all
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66
What term describes the membrane potential in the Post syn memb?
.
67
Over what time scale does the induced postsyn depolarisation happen in?
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68
What channels are on the muscle membrane? What are these permeable to? Equally permeable to each?
What is the equilibrium potential for these channels?
.
69
What does the depolarisation need to reach before an AP is caused?
.
70
What term is used to describe the type of conduction in the synaptic terminal?
.
71
What is the synapse between a nerve and muscle cell called?
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72
What is special about the EPP at the NMJ?
.
73
How is the EPP at the NMJ different to those in the CNS? Why is this?
.
74
What do CNS neurons need to induce an AP?
.>
75
The NMJ uses ACh to excite muscles, what occurs in the CNS?
.>
76
Where are presynaptic vesicles clustered? What are these areas called?
.>
77
What types of muscle do vertebrates have? Sketch and label each
.
78
Describe the structure of vertebrate skeletal muscle
| What is the diameter of a fibre?
.
79
Which of the muscle types is striated?
Can you recognise histograms of each?
What are the stripes?
.
80
Why cant you see stripes in smooth muscle?
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81
In muscle:
What is the dark band caused by?
What is the light band caused by?
.
82
What separates sarcomeres?
.
83
What makes up myosin? Sketch?
.
84
Where is the ATPase in myosin?
.
85
Why does the head point away from the centre in myosin?
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86
Sketch and label a sarcomere
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87
What makes up actin?
.
88
What is the name of the theory that describes contraction?
.
89
What bands remain constant and which shorten on contraction?
.
90
Describe the steps in cross bridge generation
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91
What characteristic of myosin enables to pull actin from ends towards centre?
What determines the force of contraction?
.
92
What does a graph of tension vs % of resting length look like? - muscles.
.
93
describe what ATP is doing in each step of contraction?
| Where does Mg come in? What is its role?
.
94
What controls contraction? What switches it off when it is not needed?
.
95
What does tropomyosin do?
.
96
What does troponin do? What makes up the complex?
.
97
Sketch what an actin filament looks like with troponin and tropomyosin labelled
.
98
What causes rigor mortis?
.
99
What stored calcium?
.
100
What part of the muscle is designed so muscle membrane depolarisation impacts the SR?
.
101
What causes muscle relaxation?
.
102
Draw a flow chart of presyn AP to muscle relaxation
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