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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
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PRODUCE MOVEMENT
MAINTAIN POSTURE
STABALIZE JOINTS
GENERATE BODY HEAT
COMPONENTS OF SKELETAL
MUSCLE
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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
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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
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Tetanus
Muscular dystrophy
Duchenne muscular dystrophy
Problems associated with steroid use.
What is the proper way to lift a heavy
object?
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Muscle twitch
Bell’s palsy
Inguinal hernia
Muscle cramp
Pictures to label