Skeletal Muscle tissue Unit 3

lecture

skeletal

voluntary striated

allows us to move/walk

moves skeleton

cardiac

involuntary striated

contracts heart which pumps blood.
- Found in the atria and ventricles of heart and contracts to move
blood

smooth

involuntary unstriated

covers organs and passageways
-Found in numerous locations including digestive tract, blood vessels
and Pumps/pushes blood/fluid/food through

skeletal muscle functions

produces movement, maintain posture, support soft tissue, guard entrances and exits, maintains body temp., provide nutrient reserves

Epimysium

-surrounds the entire muscle

-is a dense layer of collagen fibers
-connects muscle to deep, dense connective tissue.
-large blood vessels and nerves enter here

Perimysium

divides the muscle into compartments called fasicles
-comprised of elastic and collagen fibers

fasicle

Compartment containing a bundle of muscle fibers

small fasiculi

responsible finely controlled movements

large fasiculi

responsible for gross movement

Endomysium

surrounds individual muscle cells and interconnects
adjacent muscle fibers

-contains blood capillaries and satellite cells
-Between the endomysium and muscle fibers are “satellite cells”
which are a type of stem cells that repair muscle.
-primarily made up of reticular connective tissue

at end of muscle epimysium, perimysium, and endomysium come together to form

tendons

where do large blood vessels not enter

endomysium

origin

point of attachment of muscle normally to the
non-moveable bone

insertion

point of attachment of muscle normally to
the moveable bone

epimysium

made up of muscle fasicles

perimysium

made up of muscle fibers

endomysium

made up of myofibrils

skeletal muscle characteristics

-large

-multinucleate

embroyonic stage

-myoblasts fuse to form muscle fibers

myoblasts that do not fuse together

satellite cells

sarcomeres

smallest functional unit of muscle fiber/cell

proteins of a sarcomere

-thick filaments (myosin)

-thin filaments (actin)

-proteins that stabilize thick and thin filaments (titin)

-proteins that regulate interactions between thick and thin filaments (troponin and tropomyosin)

thick filament made up of

myosin

thin filament made up of

actin

m-line stabilizes

thick filaments

during contraction what happens to thin filament

thin filament gets pulled toward m-line

during contraction what happens to h-zone

h-zone gets smaller

during contraction what happens to zone of overlap

zone of overlap gets larger

during contraction a-band

stays the same

during contraction I-band

gets smaller