Topic 11.2: Muscles and Movement Flashcards
What is the role of bones in human movement?
Provide a hard framework for stability and acts as levers (3rd class) to facilitate movement
What is the role of ligaments in human movement?
Holds bones together
What is the role of muscles in human movement?
Provide the force required for movement by moving one bone (point of insertion) in relation to another (point of origin)
What is the role of tendons in human movement?
Connect muscles to bones
What is the role of nerves in muscle movement?
Motor neurons provides the stimulus for muscle movement and co-ordinates sets of antagonistic muscles
What is A?
Humerus
What is Part B?
Triceps
What is Part C?
Joint Capsule (with synovial fluid)
What is Part D?
Cartilage
What is Part E?
Ulna
What is Part F?
Radius
What is Part G?
Biceps
What is the function of the biceps?
Bends the arm (flexor)
What is the function of the triceps?
Straightens the arm (extensor)
What is the function of the humerus?
Anchors muscle (muscle origin)
What is the function of the radius/ulna?
Acts as forearm levers (muscle insertion) - radius acts as a lever for the biceps, ulna acts as a lever for the triceps
What is the function of the cartilage?
Allows easy movement (smooth surface), absorbs shock and distributes load
What is the function of synovial fluid?
Provides food, oxygen and lubrication to the cartilage
What is the function of the joint capsule?
Seals the joint space and provides passive stability by limiting range of movement
What are the similarities between the hip joint and knee joint?
Both are synovial joints
Both are involved in the movement of the leg
What are the differences between the hip joint and knee joint? (4)
Describe the structure of striated muscle fibres, including the myofibrils with light and dark bands, mitochondria, the sarcoplasmic reticulum, nuclei and the sarcolemma (6)
Each muscle fibre has the following specialised features designed to facilitate muscular contraction
Many nuclei (fibres are long and were formed from many muscle cells fusing together, hence the fibres are multinucleated)
Large number of mitochondria (muscle contraction requires a lot of ATP)
Tubular myofibrils, divided into sections called sarcomeres, and made of two different myofilaments (proteins responsible for contraction)
Where thin (actin) and thick (myosin) filaments overlap, a dark band occurs, and this is flanked by light regions containing thin filament only
The membrane surrounding a muscle fibre is called the sarcolemma
The internal membranous network is called the sacroplasmic reticulum, it is analogous to endoplasmic reticulum but is specialised for muscle contraction (it contains high levels of Ca2+ ions)
What is Part A?
sarcoplasmic reticulum
What is Part B?
nucleus
What is Part C?
mitochondria
What is Part D?
myofibril
What is Part E?
thick (myosin) and thin (actin) filaments
What is Part F?
sarcolemma
What is Part A?
Z line
What is Part B?
actin
What is Part C?
myosin (with heads)
Explain how skeletal muscles contract, including the release of calcium ions from the sarcoplasmic reticulum, the formation of cross-bridges, the sliding of actin and myosin filaments, and the use of ATP to break cross-bridges and reset myosin heads (7)
An action potential from a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum
Calcium ions expose the myosin heads by binding to a blocking molecule (troponin complexed with tropomyosin) and causing it to move
The myosin heads form a cross-bridge with actin binding sites
ATP binds to the myosin heads and breaks the cross-bridge
The hydrolysis of ATP causes the myosin heads to change shape and swivel - this moves them towards the next actin binding site
The movement of the myosin heads cause the actin filaments to slide over the myosin filaments, shortening the length of the sarcomere
Via the repeated hydrolysis of ATP, the skeletal muscle will contract
