muscles. muscle/mustut.htm muscle/mustut.htm
TRANSCRIPT
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
• 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
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
PROTEINS OF MYOFILAMENTS
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
SLIDING FILAMENT THEORY
• 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
THE 5 GOLDEN RULES OF SKELETAL MUSCLE
ACTIVITY
• 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
Pictures to label