Bones - provides anchorage for muscles and articulates with other bones
Ligaments - connects bones together
Muscles - contract to cause movement, anchors with bones
Tendons - attaches muscles to bones at their points of anchorage
Nerves - triggers action potentials to stimulate muscle contraction
Diagram of the human elbow joint
(ib.bioninja.com.au)
Functions in the human elbow joint
Radius - lever for biceps
Ulna - lever for triceps
Biceps - bends the arm
Triceps - straightens the arm
Cartilage - absorbs shock and distributes load
Joint capsule - provides stability by limiting movement
Synovial fluid - nourishes the capsule
Humerus - anchors muscle
Hip joint and knee joint
Similarities:
Both are synovial joints and involved in movement of leg
Differences:
The hip joint is a ball and socket joint, movements are three plane and through circumduction. Hip joint located between pelvis and femur.
Knee joint is like elbow (hinge) joint, movements are one plane and through extensions and flexions. Knee joint located between femur and tibia.
Structure of striated muscles
Individual parallel myofibrils within plasma membrane known as sarcolemma, together with cytoplasm; in between it is packed with mitochondria in cytoplasm.
Sarcolemma infolds to form a system of transverse tubular endoplasmic reticulum - sarcoplasmic reticulum; arranged as a network around individual myofibrils.
Sarcomere structure
(ib.bioninja.com.au)
Skeletal muscle contraction
Action potential triggers the release of Ca ions. The calcium ions bind to the myosin heads, releasing the blocking protein which exposes the binding sites (myosin head).
Myosin forms cross bridge to the actin; ATP binds and breaks the cross bridge.
Hydrolysis of ATP causes the myosin head to shift and swivel at a 45 degree angle, which moves the myosin to the next actin binding site.
Movement of myosin heads causes the actin filaments to slide over the myosin.
Continual hydrolysis of ATP causes muscle to contract.
Contraction of muscle fibres
No comments:
Post a Comment