Muscular System Flashcards

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1
Q

What are the features and example of skeletal muscle tissue

A

quadriceps
voluntary control, attached to bones, striated appearance

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2
Q

what are the feature and example of cardiac muscle tissue

A

wall of the heart
Involuntary control
Striated appearance

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3
Q

what are the feature and example of smooth muscle tissue

A

organs/ blood vessel
involuntary control, smooth appearance ( no striation )

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4
Q

outline the types of muscle action

A

Concentric- muscle contracts ( shortens)
Eccentric- muscle elongates
Isometric- muscle contracts but no movement
Isotonic- change in length to produce force

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5
Q

outline the gross structure of the skeletal muscle tissue

A

Epimysium- connective layer that surrounds the whole muscle, separates from other organs
Perimysium- surrounds bundles of fibres ( fascicles), allows for fascicles to be stimulated
Endomysium- surrounds each individual muscle fibre ( cell)

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6
Q

Define the following
Sarcolemma
Myofibrils
Transverse Tubles
Sarcoplasmic Reticulum

A

Sarcolemma- cell membrane, lipid bi-layer, conducts AP
Sarcoplasmic Reticulum- network of tubular channels, propagate action potentials
Myofibrils- cylindrical functional units within fibres, run parallel to fibres long axis
Transverse Tubules- tube system between SE, pass through the fibre, propogate AP to deeper interior

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7
Q

Define the folowing: Sarcomere, contractile proteins and Z line

A

Sarcomere- basic contractile unit of a myofibril, light and dark bands ( filaments) give ‘striated’ appearance
Actin- thin filament
Myosin- thick filament
Z line- separate sarcomeres, attachment site of actin

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8
Q

outline the MAIN steps for the contraction of the sacromere

A

Cross bridge formation
Power Stroke
Detachment of myosin
Resetting of myosin head

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9
Q

explain the cross bridge formation

A

Calcium binds to troponin
Myosin heads attach to actin binding sites
Myosin head is bound to ADP and Pi
Considered ‘energised’ and yields energy

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10
Q

Explain the power stroke step

A

Myosin head releases ADP & Pi
Myosin head used energy to pull actin filament
Actin & Z discs move towards centre of sacromere

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11
Q

Explain the steps of the detachment of myosin and resetting of myosin head

A

ATP is required to remove myosin, enables myosin to reset
ATP is hydrolysed into ADP + Pi
Energy released ‘energises’ the myosin head

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12
Q

Outline the process of excitation- contraction coupling

A

Excitation- Motor neuron delivers action potential to muscle fibres
Chemical synapse at neuro muscular junction ( Acetycholine), triggers AP in the sarcolemma of muscle fibre
Action potential travels along sarcolemma & down T-tubules
Contraction- AP causes SR to release calcium, calcium binds to troponin

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13
Q

what are the 3 main muscle fibre categories

A

Slow Oxidative ( Type I)
Fast oxidative- glycolytic ( Type IIa)
Fast glycolytic ( Type IIx)

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14
Q

Outline the size principle

A

Motor Units recruited from smallest -> largest

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15
Q

force generating capacity are affected by…

A

Motor unit recruitment ( magnitude & order); muscle temperature; stimulation frequency; resting length of fibres/ sacromere

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16
Q

Define muscle fatigue

A

any exercise-induced reduction in the ability to exert muscle force/power, regardless of whether the task is sustained
Can have central and peripheral origins

17
Q

Define peripheral fatigue

A

loss of force producing capacity due to process at or below the neuromuscular junction
Synapse of AP, Excitation of sarcolemma & myofibrils, cross - bridge cycling

18
Q

Define central fatigue

A

loss of force producing capacity due to process above the neuromuscular junction- essentially the CNS, brain and spinal cord
activation of motor cortex, propagation of command along spinal cord and activation of motor units

19
Q

Give definition of voluntary activation of the muscle

A

Ability to generate and propagate the nerve impulse
Progressively declines through exercise= central fatigue

20
Q

What are some factors affecting muscle fatigue

A

Task related- exercise duration and intensity, dynamic vs isometric
Physiological characteristics- Biological sex, metabolic capacity

21
Q

how are central & peripheral mechanism linked by

A

Afferent feedback

22
Q

short duration, high intensity of work is mainly associated with

A

Peripheral
large disturbances to metabolic homeostasis

23
Q

longer duration of exercise is mainly associated with

A

central
progressive fall in voluntary activation