Muscles Flashcards
What are muscles
Cells arranged to form fibres -> when fibres contract, they become shorter, producing force
What are the 3 types of muscle
- Skeletal (/voluntary/striated)
- Smooth (involuntary)
- Cardiac
Features of skeletal muscle
Features of smooth muscle
Features of cardiac muscle
What are myofibrils
Actin (thin filament) structure details
Myosin (thick filament) structure
How is muscle contraction initiated?
- wave of depolarisation & action potential travels down the sarcolemma & transverse tubules into the muscle fibre
-> Ca2+ diffuse out of the sarcoplasmic reticulum & into the sacroplasm of the muscle fibre / into the muscle cell
Then, Ca2+ binds with troop in molecules -> this initiates muscle contraction
What happens to myosin & what happens to actin when muscles are released
Myosin = the myosin head has ADP attached to it
Actin = troponin holds tropomyosin in place to cover the actin-myosin binding site
Contraction is caused by the interaction of…?
Myosin & actin
Muscle fibre structure diagram
Myofibril structure diagram e.g. A band, I band, M line, z disc etc
What’s the A band
Contains actin & myosin
Remains same width (during contraction)
Whats the I band
Contains only actin
What’s the M line
Where all of the myosin joins together
What’s the H zone
- contains only myosin
- in centre of sac Romero
- no overlap of light & dark bands
What happens during contraction (explain using this image)
- Z lines move towards each other
- Sacromeres get shorter
- actin slides over myosin
- H zone & I band = shorter
- A bands stay same length
What’s a sacromere
Basic functional unit of a fibre, the distance between 2 Z lines
What’s the sarcoplasm & what does it contain
The shared cytoplasm within fibres
-> contains many mitochondria & extensive sarcoplasmic reticulum
What’s the sarcoplasmic reticulum / what does it have / what does it surround?
Specialised ER
Surrounds thick & thin filaments, stored Ca2+ ions, has protein pumps to transport Ca2+ into lumen of sarcoplasmic reticulum
What are the 3 processes in the sliding filament model
Stimulation
Attachment
Detachment
What happens in stimulation of the sliding filament model
What happens in attachment of the sliding filament model
