Skeletal system Flashcards
(26 cards)
What is the main function of the muscular system?
To maintain posture and produce movement.
What is a muscle fibre?
A single muscle cell, made up of myofibrils and surrounded by connective tissue.
What are myofibrils?
Long, thread-like structures within muscle fibres, composed of repeating sarcomeres.
What are sarcomeres?
The basic contractile units of muscle, made up of actin and myosin filaments.
What two main proteins make up myofibrils?
Actin and myosin filaments.
How do actin and myosin differ in thickness?
Actin filaments are thinner than myosin filaments.
What is the function of tendons?
To connect skeletal muscles to bones, transmitting the force of muscle contraction to create movement.
What is an agonist in muscle movement?
The muscle that brings about the desired movement (prime mover).
What is an antagonist in muscle movement?
The muscle that opposes the action of the agonist.
What are antagonistic muscle pairs?
Pairs of muscles that work against each other; one contracts while the other relaxes.
What is the prime mover (agonist) in a bicep curl?
The biceps brachii muscle.
What is the antagonist in a bicep curl?
The triceps brachii muscle.
What is the sliding filament theory?
It explains muscle contraction as the sliding of thin (actin) and thick (myosin) filaments past each other to shorten the sarcomere.
How does the sliding filament mechanism work?
Myosin heads attach to actin, pull inward using ATP, the sarcomere shortens, and the muscle contracts.
What triggers muscle contraction?
Myosin uses energy from ATP to pull on actin, causing the muscle to contract.
What happens when the contraction stimulus stops?
Myosin and actin detach, and the muscle relaxes.
What role does ATP play in muscle contraction?
It provides the energy required for myosin to pull on actin and detach for the next cycle.
What are the dark and light bands in myofibrils?
The dark bands are where thick myosin filaments overlap with thin actin filaments, and the light bands are where only actin is present.
What happens to the sarcomere during muscle contraction?
It shortens as actin and myosin filaments slide past each other.
What happens to the muscle when the actin and myosin detach?
The muscle relaxes and returns to its original length.
What connects skeletal muscles to bones?
Tendons.
What is the basic function of skeletal muscles?
To pull (but not push) bones together to produce movement.
How are skeletal muscles organized to produce movement?
Through the actions of paired muscles, with others acting as stabilizers.
What is the role of stabilizer muscles?
To support and hold the body steady during movement.
