Muscles 2

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  • Created by: Hindleyc
  • Created on: 10-04-19 16:40
What is skeletal muscle, how is each muscle attached to skeleton
Striated muscle, each muscle attach to skeleton by tendons and under voluntary control
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What is muscle composed of
series of bundles
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What are groups of muscle fibres surrounded by
connective tissue
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What do they contain
Blood vessels and nerves- has own blood and nerve supply
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What are cells/fibres
Big in muscle fibre- cells fuse during development to form a very long strong multinucleate celll that can withstand very high tension- stripy arrangement of proteins
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What are skeletal muscle fibres
large cells (80 diameter can be several cm long)
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What does each fibre contain
A large number of myofibrils within the cytoplasm called the sarcoplasm in the muscle cells) and like fibres exhibits striated pattern under microscope
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What is it made of
Proteins which is what makes muscle fibre look stripy, stripes line up with each other parallel
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What is the sarcomere
Functional unit that repeats and pattern of banding on myofibrils is caused by the sarcomere
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What may the myofibril be made up of
1000s of sarcomere and if many contract the whole muscle contracts
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What is the sarcomere the smallest of in a muscle
Contractile unit which are arranged end to end for the entire length of each myofibril
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Types of sarcomere
Light, dark and v dark
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What is each sarcomere formed from
1000s of protein filaments
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What can these proteins do
slide together shortening the sarcomere which is the basis of muscle contraction
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What is each muscle fibre covered by
Cell surface membrane called a sarcolemma
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What does this do
Folds deeply into the interior of the cell in places forming T tubules (transverse tubules)
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What are the other components of the muscle fibre
Similar to other cells but their structure does look different
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What does each muscle cell/fibre have
Several nuclei located near the surface of the fibre
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Inside the cell what are there
several bundles of myofibrils that contain actin and myosin and run along the length of the cell
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What is there a large number of
Mitochondria which lie alongside the myofibril but structures only viable with an electron microscope
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What is myosin
Thicker- 15nm
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What is actin
Thinner 7nm
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Light
Actin only
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Dark
Myosin only
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V dark
Actin and myosin- 2 filaments overlap
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What is one end of each actin filament anchored to
A structure called a Z disc or Z line running across the myofibril
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What is the part of the myofibril between two z lines
sarcomere
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What is the sarcomerre
Functional unit of the muscle and it is this unit that is capable of contraction
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When muscle contracts what do the filaments do
Overlap/slide over each other
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How are filaments arranged
In an interlocking pattern within the sarcomere producing the characteristic binding pattern of the myofibrils
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What is the sarcomere
Z lines with actin from both and myosin in middles
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Z lines
Define limits of the sarcomere and appear as thin dark lines under a microscope
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What does it hold
groups of actin filaments together
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What is the I band
Regions that contain only actin filaments with lightest coloured bands of the sarcomere when viewed under a microscope nearest Z line
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What is the A band
Same length as the myosin filaments containing both the H zone and M line- Actin and myosin interlock (overlap)
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What is H zone
lies within A band, region of A band that only contains myosin filaments
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When does H zone end
where myosin and actin filaments begin to interlock
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So what is Z line
Start and end of sarcomere that defines units and gives actin something to anchor themselves to
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Any myosin=
A band (dark)
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Myosin on own=
H zone (intermediate in colour)
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Actin on own
I band (light)
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What is the M line (centre)
Found at centre of myosin filaments no head
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What decreases as region of overlap increases
I band (actin) and H zone (myosin)
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What stays the same
A band
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Why
As all myosin
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What don't muscles have
An infinite amount of contracting power
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What do thick and thin filaments allow
Them to slide past one another decreasing length of sarcomere meaning banding pattern is changed therefore light bands shrink as filaments become more interlocked
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Other cards in this set

Card 2

Front

What is muscle composed of

Back

series of bundles

Card 3

Front

What are groups of muscle fibres surrounded by

Back

Preview of the front of card 3

Card 4

Front

What do they contain

Back

Preview of the front of card 4

Card 5

Front

What are cells/fibres

Back

Preview of the front of card 5
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