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Semester 3 > Case 9 - muscle and movement > Flashcards

Case 9 - muscle and movement Flashcards

1
Q

features of skeletal muscle

A

connected to bone
striated
voluntary
high power
usually relaxed

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2
Q

features of cardiac muscle

A

heart
striated
involuntary
high power
pump (cyclic)

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3
Q

features of smooth muscle

A

hollow organs
smooth
involuntary
low power
usually contracted

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4
Q

neuromuscular junction diagram

A
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5
Q

neuromuscular junction diagram

A
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6
Q

what is in a sarcomere

A

a number of different proteins in highly organised structure

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7
Q

how does muscle contract

A

by overlapping the filaments

using energy derived from ATP hydrolysis to power this mechanism which is progressively shortening the distances

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8
Q

what is the thin filament

A

actin

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9
Q

what is the thick filament

A

myosin

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10
Q

where is tropomyosin normally sat

A

over the binding sites for myosin on actin

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11
Q

what has to happen in order fr the myosin to bind to the myosin binding site on actin

A

the binding site has to be exposed. when there is little Ca2+ or none, tropomyosin moves down and covers the binding sites. means that the actin and myosin can’t interact and bind to each other therefore giving no muscle contraction

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12
Q

what is the troponin complex

A

series of regulatory proteins and in the presence of calcium, they help to move that tropomyosin out of the myosin binding site and allows the actin and myosin to interact. you then get ATP hydrolysis that powers the whole process. effectively makes the muscle shorter

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13
Q

striated muscle contraction series of events

A
  1. ATP binds to the myosin head causing the dissociated of the actin-myosin complex
  2. ATP is hydrolysed, causing myosin heads to return to their resting connotation
  3. a cross bridge forms and the myosin head binds to a new position on actin
  4. phosphate is released… myosin heads change conformation resulting in the power stroke. the filaments slide past each other
  5. ADP is released
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14
Q

what happens when there are high levels of calcium

A

you get contraction

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15
Q

diagram with anatomy concerning excitation-contraction coupling

A
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16
Q

what is the plasma membrane

A

the sarcolemma

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17
Q

what are there lots of in the muscle cell

A

myofibrils

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18
Q

what do the invaginations of the plasma membrane form

A

transverse tubules

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19
Q

what interacts with the transverse tubule

A

the sarcoplasmic reticulum cisterns

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20
Q

where does the action potential go

A

goes along the sarcolemma and finds its way down into the T tubules and the T tubule is running very close to the SR. t

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21
Q

where is calcium stored

A

the SR.

when the muscle is relaxed, the Ca2+ will be locked up inside the SR

when the cells contract, Ca2+ will be released

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22
Q

when do we get release of calcium

A

when a wave of depolarisation passes through the T tubule

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23
Q

what does the twitch force depend on

A

how much calcium is released. bigger contraction when more calcium is released

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24
Q

what are the two types of contraction

A

isometric
isotonic

25
Q

what is isometric contraction

A

a constant length and doesn’t actually shorten

26
Q

what is isotonic contraction

A

a constant load

27
Q

what does isotonic muscle contraction produce

A

limb movement without change in muscle tension, whereas isometric muscle contraction produced muscle tension without a change in limb movement. most physical activities involve a combination of both forms of muscle contraction, although one form usually predominates

28
Q

more on isometric contraction

A

contraction is stronger the closer the muscle initial length is to the optimum length

a muscle contracts but the joint is controls does not move

29
Q

more on isotonic contraction

A

contraction is faster the closer the muscle initial length is to the optimum length

a muscle contracts and the joint angle it controls increases and decreases while the muscle either shortens or lengthens

30
Q

what is a muscle unit

A

muscle fibres innervated by a single motor neurone

31
Q

what is a motor unit

A

muscle unit plus its motor neurone

32
Q

what is a motor neurone pool

A

collection of neurones innervating a single muscle

33
Q

what is involved in fine control

A

few muscle fibres per motor unit

34
Q

what is involved in coarse control

A

any muscle fibres per motor unit

35
Q

how many motor neurones control a muscle

A

typically about 100

36
Q

what are the features of type 1 muscle

A

oxidative slow, red
slow myosin response time
moderate rate of Ca2+ pump transport
moderate diameter
high oxidative capacity
moderate glycolytic capacity
reistant to fatigue

37
Q

what are the features of type 2B muscle - 7

A

glycolytic fast, white
fastest myosin response time
high Ca2+ pump transport rate
large diameter
low oxidative capacity
high glycolytic capacity
non-resistant to fatigue

38
Q

what are the features of type 2A muscles - 7

A

glycolytic, fast, red
fast myosin response time
high Ca2+ pump transport rate
small diameter
very high oxidative capacity
high glycolytic capacity
resistant to fatigue

39
Q

which muscle type is good for long distance running and why

A

type 1 fibres are slow and oxidative and tend to rely on aerobic respiration to generate most of their force - long distance run at low speed

40
Q

which fibres fatigue slower than 2B

A

2A but generate a decent amount of tension

41
Q

what are 2B designed to do

A

give you high energy. relying on glycolysis anaerobic respiration to give out most of their power.

42
Q

what are the two mechanisms to increase the amount of force

A

recruitment of motor units

firing rate of motor units (shortening the time between action potentials and the contractions sort of add together and the calcium is never fully mopped up by the SR)

43
Q

what is the sequence of recruitment in the gradation of muscle force

A

S->FR->FF

44
Q

what are the large motor unit properties

A

motor neurone: large, fast conduction, hard to excite

Muscle fibres: many, type 2 (large, fast glycolytic)

Activity: recruited if a strong contraction is required, usually inactive

45
Q

what are the small motor unit properties

A

motor neurone; small, slow conduction, easy to excite

Muscle fibres: few, type 1 (small, slow, oxidative)

Activity: first to be recruited, frequently active

46
Q

detailed stretch reflex diagram

A
47
Q

LMN muscle strength

A

weak

48
Q

what type of paralysis do you get with LMN lesion and why

A

flaccid - effectively damaged the wiring between the muscle and the spinal cord; cant get a message from the spinal cord to the muscle

49
Q

what is the muscle tone if you have a LMN lesion

A

hypotonia

50
Q

what is the type of reflex if there is a LMN lesion

A

hyporeflexia

51
Q

muscle strength in UMN lesion

A

weakness

52
Q

what type of paralysis do you get in UMN lesion

A

you get spasticity because the wiring is still there form the muscle unlike in an LMN lesion: can’t get the message from the motor cortex to the spinal cord. you get sensitisation of the lower motor neurone pools so that they’re responding in the absence of innovation from the motor cortex. that is why you get spastic paralysis

53
Q

what type of muscle tone is there in UMN lesion

A

hypertonia - thanks to sensitisation to lower motor pools

54
Q

what sort of reflexes do you get. in UMN lesion

A

hyperreflexia

55
Q

what is Babinski sign

A

may show a problem in the corticospinal tract. CST is a neural pathway that goes from your brain to spinal cord and helps control your movements. evaluate neuro only in patients above age of 2.

the essential phenomenon appears to be recruitment of the extensor hallicus Longus, which consequent overpowering of the toe flexors. the movements of the other joints remain the same

56
Q

how what happens when the corticospinal tract is not functioning

A

The corticospinal tract influences the segmental reflex in the spinal cord. When the corticospinal tract is not functioning properly, the result is that the receptive field of the normal toe extensor reflex enlarges at the expense of the receptive field for toe flexion. Toe extension is consequently elicited from what is normally the receptive field for toe flexion.

57
Q

what is the plantar reflex

A

a nociceptive segmentaal spinal reflex that serves the purpose of protecting the sole of the foot

58
Q

in what conditions has the extensor reflex been observed

A

hemorrhage, brain and spinal cord tumors, and multiple sclerosis, and in abnormal metabolic states such as hypoglycemia, hypoxia, and anesthesia.[2]

Semester 3 (94 decks)

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