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BMS1052 > Movement 1&2 > Flashcards

Movement 1&2 Flashcards

1
Q

WHat types of movement do lower motor neurons control

A

both reflexive and voluntary

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2
Q

location of soma, axon and synapses of LMS

A

soma: gray matter of spinal cord
axon: dorsal root
synapses: muscle fibre

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3
Q

define: motor unit

A

LMN and all the muscle fibres it innervates

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4
Q

define: motor neuron pool

A

all LMNs innervating muscle fibres of a particular muscle.

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5
Q

describe rate coding, (un)fused tetanus

A

rate of AP determines force.
unfused tetanus: lower rate, so bumps in force/time graph
fused tetanus: faster rate, smooth

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6
Q

describe size principle

A

involves size of motor units

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7
Q

small vs large motor units

A

small: LMN which has small cell body and innervates fewer muscle fibres (<10)
large: large cell body, innervates many muscle fibres (,1000)

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8
Q

why are small motor units recruited first to generate graded forces

A

V=IR
I = current: same
R= resistance: larger for low SA hence small motor units
therefore, small motor units reach threshold easier and hence are recruited first

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9
Q

describe proportional control

A

many small motor units which generate less force, and fewer large motor units, which generate more force

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10
Q

what happens during excitation?

A

AP stimulates Acl release from presynaptic neuron, which binds to receptor on muscle fibre.
ions go in, then volage gated Na+ channels open.
AP goes along transverse tubules, opens up dihyropyridine receptors and then ryanodine receptors, triggering release of Ca2+ from lateral sac of sarcoplasmic reticulum.

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11
Q

what happens during contraction

A

Myosin head has ADP and Pi attached (energised)
Tropomyosin shields myosin from actin. Ca2+ causes troponin to move tropomyosin, enabling binding of myosin head to actin.
Power stroke happens, ADp and Pi released
ATP binds, breaking actin-myosin bond
ATP hydrolyses and cycle continues.

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12
Q

how does contraction stop

A

Ca2+-ATPase carries Ca2+ back into sarcoplasmic reticulum.

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13
Q

describe myofibril/sarcomere structure

A

LOL

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14
Q

describe the length/tension relationship

A

optimum tension at a medium length.

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15
Q

isotonic definition and graph of time vs distance shortened?

A

same tension, different lenght.
takes time for length to shorten, as enough cross bridges must be formed to counteract the load.
finishes as soon as load returns to resting position

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16
Q

isometric definition and time vs tension graph?

A

same length, increased tension.
increases tension right away
takes time for tension to return to normal as Ca2+ must be seuestered

17
Q

describe concentric

A

muscle shortens as tension increases, as cross bridge forms further up actin, leading to shortening

18
Q

describe eccentric

A

muscle increases in length as tension increases due to external pressure.

19
Q

factors determining the three types of muscle fibres?

A

maximum shortening velocity
-type i: slow, low ATPase activity
-type ii: fast, high ATPase activity
whether glycolytic or oxidative

20
Q

what are the three muscle fibre types

A
  • Type I – slow oxidative
  • Type IIa – fast oxidative-glycolytic
  • Type IIb – fast glycolytic
21
Q

order of recruitment of the 3 types of muscle fibres?

A

1 –> 11a –> 11b

because they correspond to small/large motor units.

22
Q

muscle fibres of one motor unit are…

A

of the same type

23
Q

a whole muscle tissue contains

A

different combinations of each muscle fibre type, depending on its needs.

24
Q

what happens when slow motor neurons are forced to innervate fast muscle?

A

changed from type ii to type i fibres; hence changed from a coral colour to a deep red

25
Q

what happens when muscle fibres are stimulated with a lower rate of AP?

A

diameter of muscle fibres decreased

26
Q

effect of curare

A

nicotonic Acl receptor antagonist

27
Q

effect of atropine

A

muscarinic Acl receptor antagonist

28
Q

effect of Latrotoxin

A

massive release of Acl, norepinephrine and GABA

29
Q

effect of botox?

A

prevents Acl release.

30
Q

during experiment three, what nerve was stimulated, which affected which muscle?

A 
ulnar nerve
hypothenar muscle (moves little finger)
31
Q

where is the ulnar nerve best stimulated and why

A

near funny bone/forearm - little fat and close to surface.

32
Q

how is AP produced?

A

using a stimulating bar

33
Q

how do we measure effect of AP?

A

EMG - detects, amplifies and records electircal activity of hypothenar muscle
transducer: detects force of little finger.

BMS1052 (20 decks)

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