410 likes | 607 Views
MUSCLES. http://www.gwc.maricopa.edu/class/bio201/muscle/mustut.htm http://www.meddean.luc.edu/lumen/meded/GrossAnatomy/dissector/mml/index.htm. THREE TYPES OF MUSCLES. Cardiac Smooth Skeletal. PROPERTIES OF MUSCLES. Ability to contract Extensibility – ability to be stretched
E N D
http://www.gwc.maricopa.edu/class/bio201/muscle/mustut.htm • http://www.meddean.luc.edu/lumen/meded/GrossAnatomy/dissector/mml/index.htm
THREE TYPES OF MUSCLES • Cardiac • Smooth • Skeletal
PROPERTIES OF MUSCLES • Ability to contract • Extensibility – ability to be stretched • Elasticity – ability to return it its original length • Irritability – ability to receive and repord to stimuli
TERMS • Myo – muscle • Sacro - flesh • Muscle fiber – individual muscle cell
SKELETAL MUSCLE • Bundles of muscle fibers that are package to form the organ
CONNECTIVE TISSUE OF SKELETAL MUSCLE • Warps or bundles up muscle fibers • Provides support and strength to muscle • Keeps muscles form being ripped apart under tremendous forces
PARTS OF MUSCLE FIBER • Endomysium – connective tissue sheath that wraps each individual muscle fiber • Perimysium – coarser fibrous membrane that surrounds several muscle fibers • Fascicle – bundle of fibers • Epimysium – tougher layer of connective tissue that covers many fascicles – covers entire muscle –
EPIMYSIUM • Ends of it will blend into • Tendons • Aponeurosis – attaches muscles indirectly to bones, cartilage or connective tissue
TERMS Origin – muscle attaches to stationary bone Insertion – muscle attaches to bone that moves When muscle contracts, one bone moves and the other is stationary
MOVEMENT OF BODY PARTS • Body part is moved by a group of muscles: • Prime mover • Synergists • fixators • Antagonists - pairs that work opposite
Tendon- connective tissue that attaches muscle to bone • Very tough – thus is gives muscles durability • Does not wear out next to rough projections of bone • Usually tendon that passes over bony joint and not muscle
Muscles are arrange differently depending on where they are located
FUNCTIONS OF MUSCLES • PRODUCE MOVEMENT • MAINTAIN POSTURE • STABALIZE JOINTS • GENERATE BODY HEAT
COMPONENTS OF SKELETAL MUSCLE • Saroclemma • Sarcoplasmic reticulum • Sarcoplasm • sarcomere
Parts of Sarcomere • Myofibril (fibril) 0 complex organelle composed of bundles of myofilaments. Fill the cytoplasm of muscles. • Myofilaments – threadlike filaments – has alternating light and dark bonds - composed of 2 key proteins • Actin • myosin
myosin • Thick protein filament • Contains ATPase – splits ATP to generate the energy needed for muscle contraction • Extends the entire length of the dark A boand • Midpart is smooth • End are studded with projections called myosin heads or cross bridges
actin • Thin filament • Made up of contractile protein • Actin is anchored to the Z line • I band – 2 adjacent sarcomeres and contains only actin • Actin does not extend into the middle of the A band which makes the H zone appear lighter
When contraction occurs – actin filament slide toward each other into the center of the sarcomeres • Light zone disappears because actin and myosin totally overlap
Relaxed muscle has regulatory proteins on the actin to prevent myosin from bending
AP stimulates the sarcolemma of the muscle • Ca ions are released from the sarcoplasmic reticulum • Ca ions bind to the regulatory proteins on the actin • This changes the shape and location of the regulatory proteins on the actin
Binding sites on the actin become exposes • Myosin heads attach to the binding sites on the actin (called cross bridge formation) • When heads attach, they snap toward center of sarcomere (power stroke) • This pulls actin toward center of sarcomere • ATP provides Energy to release and recock myosin heads
Cross bridge is broken • Myosin head reattaches to another site further along the actin (another cross bridge and power stroke) • This is called walking of the myosin • AP ends • Ca ions reabsorbed by sarcoplasmic reticulum
Regulatory proteins return to their original shape and position • Myosin can’t attach • Muscle relaxes
MACROSCOPIC CONTRACTION • Muscle cell - all or none response • Thousands of muscle cells form the organ • Skeletal muscle’s response is graded – different degrees of contraction
2 WAYS TO PRODUCE GRADED REPONSE • 1 - Changing the speed of muscle stimulation • 2 - Changing the number of muscle cells stimulated
Pat vs. slap • If few cells (motor units) are stimulated, then the contraction of the muscle is slight. • As more cells are stimulated, the grater the contraction
All muscles cross at least 1 joint • The bulk of the muscle lies proximal to the joint crossed. • All muscles have at least 2 attachments • Muscles can only pull, they never push • During contraction muscle moves toward the origion
DISEASES • Tetanus • Muscular dystrophy • Duchenne muscular dystrophy • Problems associated with steroid use. • What is the proper way to lift a heavy object?
Muscle twitch • Bell’s palsy • Inguinal hernia • Muscle cramp