Topic 11.2 Muscles and Movement

11.2.1 Role of bones, ligaments, muscles, tendons and nerves in human movement JOINT aka articulation or arthrosis point where 2 or more bones contact one another arthrology = study of joints rheumatology = branch of medicine dealing with joint diseases and conditions kinesiology = study of movement of the body joints provide mobility most joints include bones, ligaments, muscles, tendons and nerves

BONES Organs contain several different tissues Functions: framework for support protect soft tissues and organs act as levers for movement form blood cells in the marrow storage of minerals, especially Ca and phosphorous adults have 206 bones Be able to identify: clavicle, ribs, humerus, ulna, radius, carpals, metacarpals, phalanges, femur, tibia, fibula, tarsals and metatarsals

Muscles and Tendons cords of dense connective tissue attach muscles to bones bones act like levers and magnify muscle contraction force muscles provide force by shortening the length of their fibers or cells antagonistic muscle pairs since only provide movement by shortening biceps bends arm, triceps straightens it

Ligaments and Nerves ligaments are tough band-like structures that strengthen joints connect bone to bone provide stability proprioceptors = sensory nerve endings which monitor positions of joint parts nerves help prevent overextension of the joint

11.2.2 Label a diagram of the human elbow including: cartilage, synovial fluid, joint capsule, bones and muscles elbow is a hinge joint joint capsule = connective tissue

11.2.3 Outline the function of structures in elbow joint Joint Part Function cartilage reduces friction and absorbs compression (shock absorber) synovial fluid lubricates to reduce friction; provides nutrients to cells of cartilage joint capsule surround joint; encloses synovial cavity; unites connecting bones tendons attach muscle to bone ligaments attach bone to bone biceps muscle contract to cause flexion (bending) of the arm triceps muscle contracts to cause extension (straightening) of the arm humerus acts as a lever that allows anchorage of elbow muscles radius acts as lever for biceps muscle ulna acts as lever for triceps muscle

11.2.4 Compare movement of hip joint and knee joint flex, extend, abduction, adduction, rotation hinge socket and ball synovial joints hip knee move the leg multiaxial moves in one axis required for walking flex, extend, a little rotation flex, extend, abduction, adduction, rotation

HIP MOVEMENTS: flex and extend = < and > angle between connecting bones abduction and adduction = move away and toward body midline combination of these = windmill effect

Muscle Types skeletal or striated cardiac or heart muscle smooth or non-striated

11.2.5 Describe structure of striated muscle fibers including: myofibrils with light and dark bands; mitochondria; sarcoplasmic reticulum; nuclei and sarcolemma

sarcoplasm = cytoplasm of a muscle cell sacroplasmic reticulum = internal membrane which stores and releases calcium ions (Ca2+) to trigger a contraction myofibrils = thin fibers that cause a striated (striped) pattern of light and dark bands; contain 2 types of myofilament, myosin and actin (protein-like substances) many mitochondria = provide energy sarcomere = the functional unit of the muscle sarcolemma- plasma membrane of muscle cell

11.2.6 Draw and label a diagram of a sarcomere including: Z lines; actin filaments; myosin filaments with heads and light and dark bands

11.2.6 (cont.) thin actin filaments attach to the Z line and form the light section, the I band actin filaments overlap with thick myosin filaments to form the dark section, the A band between the two Z lines, you find myosin only intermediate section, the H zone sarcoplasmic reticulum regulates Ca ion movement Ca2+ concentration determines ATPase activity; ATPase is an enzyme which hydrolyzes ATP to release its E

11.2.7 Explain how skeletal muscle contracts Sliding filament theory = actin myofilaments slide over myosin myofilaments myofilaments do not shorten – when actin slides over myosin the sarcomere shortens Sliding Filament Theory: motor neuron carries impulse to neuromuscular junction neurotransmitter (acetylcholine) released into synapse between axon terminal and sarcolemma of muscle fiber

acetylcholine binds to receptors on sarcolemma ion channels open and Na ions move through the membrane this generates a muscle action potential causes release of Ca ions from sarcoplasmic reticulum ATP is hydrolyzed releasing E myosin heads bind to the actin myosin slides along actin shortening the sarcomere

11.2.8 Analyze electron micrographs to find the state of contraction of muscle fibers Z line between Z lines = a sarcomere I band H zone A band