6: Muscle Structure Flashcards
(24 cards)
What is the contracting muscle in an antagonistic pair called?
The agonist
What is the relaxing muscle in an antagonistic pair called?
The antagonist
What are muscle cells called?
Muscle fibres
What is the cell membrane of muscle fibres called?
The sarcolemma
What is the cytoplasm of muscle fibres called?
The sarcoplasm
What are the transverse (T) tubules?
Bits of the sarcolemma folded inwards into the sarcoplasm
What is the function of the transverse (T) tubules?
Help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre
What is the sarcoplasmic reticulum?
A network of internal membranes that runs through the sarcoplasm
What is the sarcoplasmic reticulum’s function?
Stores and releases calcium ions that are needed for muscle contraction
Muscle fibre properties/ adaptations?
Lots of mitochondria, multinucleate, lots of myofibrils
What are myfibrils?
Long, cylindrical organelles made up of proteins that are highly specialised for contraction
What are the thick filaments made from?
Myosin
What are the thin filaments made from?
Actin
What are A-bands?
Dark bands containing the myosin filaments and same overlapping actin
What are I-bands?
Light bands containing actin only
What are the ends of a sarcomere called?
Z-line
What is a sarcomere?
A short unit of a myofibril
What is the M-line?
The middle of the myosin filaments
What is the H-zone?
Only myosin, around the m-line
What theory explains muscle contraction?
The sliding filament theory
What happens to A-bands when the muscle contracts?
Stay the same length
What happens to I-bands when the muscle contracts?
Gets shorter
What happens to H-zones when the muscle contracts?
Gets shorter
How to remember which areas change when a muscle contracts?
A-bands are the only ones which stay the sAme
