Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

human physiology and exercise > skeletal muscle > Flashcards

skeletal muscle Flashcards

1
Q

macroscopic to microscopic structure

A

muscle > muscle fascicle > muscle fibre > myofibril > sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are sarcomeres?

A
  • structural unit of myofibril in striated muscle
  • dark and light bands due to actin and myosin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what cell types are muscles comprised of?

A
  • muscle fibres
  • vascular cells
  • fibroblasts
  • satellite cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

where do forces come from?

A
  • interactions between myosin and actin forming cross- bridges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how many actin for every one myosin?

A
  • six
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does the Z lines indicate?

A
  • boundaries of each sarcomere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the m- line?

A
  • located in middle of sarcomere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does the I- band consist of?

A
  • thin filaments only
  • lighter due to actin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does H zone consist of?

A
  • thick filaments
  • heavy as only myosin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does the A band consist of?

A
  • 2 myofilaments overlap
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what happens to the bands during contraction?

A
  • A band remains same
  • I band reduced as actin filaments move towards each other
  • H zone reduced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what do muscle spindles detect?

A
  • stretch in muscles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what do muscle fibres prevent and how?

A
  • prevents overstretching
  • if contracting too much the antagonistic muscle will contract to reduce effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the role of titin?

A
  • protein that helps to stabilise and stretch sarcomeres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

why is there a membrane around myofibril?

A
  • helps with contraction of fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the sarcoplasmic reticulum?

A
  • forms sleeve like segment around each myofibril
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the role of mitochondria?

A
  • helps to generate ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are transverse tubules?

A
  • lies adjacent to SR and action potentials travel down them which is important for release of calcium ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is a motor unit?

A
  • motor neurone and its muscle fibres
  • spinal cord> motor neurone> muscle fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how many fibres can one motor neuron innervate?

A
  • many muscle fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

why are action potentials propagated?

A
  • to fibres to cause contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what does the journey of action potential depend on ?

A
  • arrangement of fibres e.g. straight through if parallel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how are charges analysed?

A
  • frequency can determine amount of force e.g. if brain sends more impulses than a bigger force will be formed = increased motor unit recruitment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the neuromuscular junction?

A
  • synapse between a motor neuron terminal and its muscle fibres
  • neuronal signals from brain/ spinal cord interact with fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are the two proteins responsible for linking membrane action potential with calcium released in the cell?

A
  • dihydropyridine (DHP) receptor (membrane)
  • ryanodine receptor (sarcoplasmic reticulum)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what does action potential cause?

A
  • depolarisation of plasma membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what does action potential cause?

A
  • calcium channels open allowing calcium ions to diffuse into axon terminals and bind to proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what do the calcium ions cause?

A

synaptic vesicles containing neurotransmitters bind to membrane and release acetylcholine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what does the acetylcholine do once released?

A
  • binds to nicotinic receptors opening ion channels ( Na+ moves in, K+ moves out)
    = electrochemical gradient across membrane
30
Q

how does the process at neuromuscular junction end ?

A
  • motor end plate depolarises
  • muscle fibre action potential initiated
  • propagation (end plate potential)
31
Q

what does every action potential in a motor neuron produce?

A
  • a action potential in each muscle fibre
  • 1:1
32
Q

how long do action potentials last in skeletal muscle?

A

1-2 mscs before mechanical activity; mechanical delay between production of electrical activity and muscle contraction

33
Q

how long does mechanical activity last following an action potential? what does it depend on?

A
  • may last 100ms or more
  • depends on availability of intracellular Ca2+
34
Q

describe a relaxed muscle

A
  • low calcium ions
  • cross bridge cannot bind with actin because tropomyosin is covering binding site
35
Q

what is tropomyosin?

A
  • chain around actin filament that blocks myosin head from attaching
36
Q

describe an active muscle

A
  • high calcium ions
  • calcium ions bind to troponin thus moves tropomyosin away from cross- bridge binding site
37
Q

what happens once motor end plate is depolarised ?

A
  • wave of depolarisation flows down t- tubules
38
Q

what is released from sarcoplasmic reticulum /cisternae and what does it do?

A
  • calcium ions
  • binds to troponin causing a shift in tropomyosin
39
Q

what happens when tropomyosin is moved?

A
  • actin binding site is exposed allowing myosin to bind
  • cross bridge forms between actin and myosin as the bridge bind, rotate and generate force
40
Q

what does calcium removal restore?

A
  • tropomyosin blocking action
41
Q

where is the calcium transported back to?

A
  • sarcoplasmic reticulum
42
Q

what is the first stage of cross- bridge cycle?

A
  • energised cross bridges bind to actin
43
Q

what does the binding to actin release?

A
  • ATP hydrolysis products from myosin, producing angular movement
44
Q

what happens after ATP hydrolysis products are released?

A
  • ATP bound to myosin breaking the link between actin and myosin
45
Q

what happens to the ATP after link is broken?

A
  • ATP bound to myosin is split energising the myosin cross bridge
46
Q

what is ATPase?

A
  • enzyme determines the speed of ATP hydrolysis and resulting sarcomere shortening velocity
47
Q

what factors affect transmission?

A
  • rate of calcium reuptake
  • rate of ATP breakdown
48
Q

what is frequency tension relationship?

A
  • frequency of vibration directly proportional to tension
49
Q

what do nonoverlapped areas represent?

A

specificity of metabolic function among the body’s three energy systems
- three overlapped portions represent generality

50
Q

what is a power stroke?

A
  • myosin pulls on actin causing actin to slide towards middle of sarcomere
51
Q

what is excitation- contraction coupling?

A

refers to sequence of events by which an action potential in plasma membrane activates force generating mechanisms

52
Q

what is the contraction time?

A

time interval from the beginning of tension development to peak tension

53
Q

what is latent period?

A
  • occurs after action potential before tension in muscle increases
    1-2 milliseconds between stimulus and initiation of contraction
54
Q

what is a muscle twitch?

A
  • mechanical response of a fibre to a single action potential
55
Q

what is summation?

A
  • increase of muscle tension from successive action potentials
56
Q

what is the sodium potassium pump?

A
  • establishes the resting membrane potential of the cells
    -70mV
57
Q

what happens at rest to the pump?

A
  • more sodium in extracellular space than when an action potential arrives
58
Q

what does the arrival of the action potential cause?

A
  • depolarisation means more sodium diffuse into intracellular space
59
Q

what is repolarisation?

A
  • restores the charge between the inside and outside of a cell membrane
60
Q

what is hyperpolarisation?

A
  • movement of a cell’s membrane potential toa more negative value
  • less likely to fire an action potential
61
Q

what does creatine phosphate provide?

A
  • fast energy to form ATP from ADP
    1-2 seconds
62
Q

what is glycolysis? - energy metabolism

A
  • energy from glucose in anaerobic conditions
    8-10 seconds
63
Q

what is oxidative phosphorylation?

A
  • energy from glucose/ fat in aerobic conditions
    2-3 days
64
Q

how are glycogen and creatine phosphate stores replenished?

A

oxygen debt= oxygen the muscles use after exercise has finished

65
Q

what is conduction failure?

A
  • muscle fatigue caused by potassium accumulation in t- tubules
66
Q

what does lactic acid build up cause?

A
  • fatigue as functioning of proteins and mechanisms involved in Ca release and uptake are effected
67
Q

what does inhibition of cross bridge cycling cause?

A
  • fatigue through the build up of ADP in muscle fibres; preventing the release of actin
68
Q

how do fuel substrates cause fatigue?

A
  • low muscle glycogen and blood glucose
  • dehydration
69
Q

what is central command fatigue? when does it occur?

A
  • failure of CNS to propagate signals from brain to motor neurones
  • happens alot in heat
70
Q

what are type 1 muscle fibres?

A
  • slow oxidative
  • high fatigue resistance + mitochondria
  • thinner and low glycolytic
  • muscle velocity 1 muscle lengths/ sec
71
Q

what are type 11a muscle fibres?

A
  • fast oxidative fibres
  • highly oxidative and moderately glycolytic
  • moderate contraction speed/ resistance to fatigue
  • muscle velocity 2.5 muscle lengths/sec
72
Q

what are type 11b muscle fibres?

A
  • fast glycolytic
  • large diameter to increase muscle force
  • low fatigue resistance +mitochondria
  • muscle velocity 3.5 muscle lengths/ sec

human physiology and exercise (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions