Muscle Ultratissue Flashcards
Types of muscle
Skeletal, cardiac, smooth
Skeletal muscle is…
Striated muscle which is under voluntary control of the somatic nervous system
Cardiac muscle is
Striated muscle found only on the heart
Smooth muscle is…
Non-striated muscle which is controlled involuntarily by the autonomic nervous system
Cell surface membrane of muscle cell
Sarcolemma
T-tubules are…
Invaginations of the sarcolemma which conduct charge when a cell is depolarised
Sarcoplasmic reticulums are…
Specialised endoplasmic reticulums which contain large storages of calcium ions
Hierarchy of muscle organisation
Muscle fibres -> fascicles -> muscle
Muscle fibres are surrounded by
Endomysium
Muscle Fascicles are surrounded by
Perimysium
Muscles are surrounded by
Epimysium
Functional unit of muscle
Sarcomere
Z line
Actin filaments are anchored
M line
Where myosin filaments are anchored
I band
Contains only actin filaments
A band
Length of a myosin filament - may contain actin also
H zone
Only myosin
Thin filament
Actin
Thick filament
Myosin
Tropomyosin runs along…
The actin filament and blocks myosin head binding sites
Troponin binds…
Tropomyosin to actin
Troponin I
Binds to the actin filament
Troponin T
Binds to Tropomyosin
Troponin C
Binds to calcium ions
1st stage of muscular contraction
Depolarisation arrives at neuromuscular junction. Conducted by T tubules - causes massive influx of calcium ions from sarcoplasmic reticulum
2nd stage of muscle contraction
Calcium binds to Troponin C - causes Tropomyosin to move away from actin filament myosin head binding sites
3rd stage of muscular contraction
Myosin heads bind to actin filaments. Power strokes cause the myosin heads to pivot in a rowing motion. This slides the actin filaments towards the M line
4th stage of muscular contraction
ATP binds to myosin heads, causing them to unbind from actin
What shortens during muscle contraction?
Distance between Z lines, I band, H zone and length of the sarcomere
What stays the same during muscle contraction
A band and length of muscle filament
Duchenne muscular dystrophy is when…
Dystrophin not produced - muscle fibres tear on contraction - muscle weakness
Sufferers of duchenne muscule dystrophy are usually…
In a wheelchair by age 12