Muscle structure Flashcards
What are three types of muscle?
Cardiac
Smooth
Skeletal
What is cardiac muscle?
Contracts without conscious control but only found in heart
What is smooth muscle?
Contracts without conscious control and found in the walls of internal organs
What is skeletal muscle?
Type of muscle you use to move
What attaches skeletal muscle to bones?
Tendons
What attaches bones to other bones?
Ligaments
What moves bones at a joint?
Pairs of skeletal muscle that contract and relax as the bones of the skeleton are incompressible so they act as levers, giving the muscle something to pull against
What are antagonistic pairs?
Muscles that work together to move a bone
In an antagonistic pair, what is the contracting muscle?
Agonist
In an antagonistic pair, what is the relaxing muscle?
Antagonist
What happens when the biceps contract?
The triceps relax
Pulls the bone so your arm bends at the elbow
Bicep is agonist
Tricep is antagonist
What happens when the triceps contract?
The biceps relax
Pulls the bone so your arm straightens at the elbow
Tricep is agonist
Bicep is antagonist
What is skeletal muscle made up of?
Large bundles of long cells, called muscle fibres
What is the membrane of a muscle fibre called?
Sarcolemma
What is a sarcoplasm?
A muscle cell’s cytoplasm
What are transverse (T) tubules?
Folds of the sarcolemma which go into the sarcoplasm
What do T tubules do?
They help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre
What is the sarcoplasmic reticulum?
Network of internal membranes
What does the sarcoplasmic reticulum do?
Stores and releases calcium ions that are needed for muscle contraction
What do muscle fibres have a lot of to provide the ATP for muscle contraction?
Mitochondria
What are myofibrils?
long, cylindrical organelles found in muscle fibres
What are myofibrils made up of?
Proteins
What do myofibrils contain?
Thick and thin myofilaments that move past each other to make muscles contract
What are thick myofilaments made up of?
Myosin
What are thin myofilaments made up of?
Actin
What are A bands?
Dark bands of thick myosin filaments and some overlapping thin actin filaments
What does the I band contain?
only contains thin actin filaments
What is a sarcomere?
A short unit which lots make up myofibril
What is the Z-line?
Marks the end of a sarcomere
What is the M-line?
The middle of the sarcomere which is also the middle of the thick myosin filaments
What is the H-zone?
only contains thick myosin filaments
What is the sliding filament theory?
Myosin and actin filaments slide over one another to make sarcomeres contract
In the sliding filament theory, what causes the myofibrils and muscle fibres to contract?
The simultaneous contraction of lots of sarcomeres
What happens to the structure of a sarcomere during contraction?
A-Bands stay the same length
I-band gets shorter
H-zones get shorter
The distance between the two Z-lines becomes shorter
