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 jointjoint 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

knee hip

synovial joints

move the leg

required for

walking

socket and ballhinge

moves in one

axis

flex, extend, a little

rotation

multiaxial

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:

1. motor neuron carries impulse to neuromuscular junction

2. neurotransmitter (acetylcholine) released into synapse between axon terminal and sarcolemma of muscle fiber

3. acetylcholine binds to receptors on sarcolemma4. ion channels open and Na ions move through

the membrane5. this generates a muscle action potential6. causes release of Ca ions from sarcoplasmic

reticulum7. ATP is hydrolyzed releasing E8. myosin heads bind to the actin9. myosin slides along actin shortening the

sarcomere

11.2.8 Analyze electron micrographs to find the state of contraction of muscle fibersZ line between Z lines = a sarcomere

I band H zone

A band