Chapter 9: SECTION A
Muscle Physiology filaments); appear darker in the ordinary
microscope
Muscle- has layers and layers of smaller components 🡺 Myosin filaments- anchored together by a
o Biceps brachi- muscle of the upper arm transecting network of proteins M line or
which is composed of bundles of muscle cells middle disk line); composed of protein
or fiber that are very long. myosin molecules w/ 2 large polypeptide
o Muscle fascicles- bundles of fibers chains & 4 smaller light chains
a. myosin head- cross bridge which forms
3 types of muscle tissues: connection between the myosin filament
⮚ Skeletal- “muscle fiber” due to elongated and actin filament during muscle
shape and presence of multiple nuclei; striated contraction; project perpendicularly;
muscle contain 1 binding site for actin filaments &
⮚ Cardiac- striated muscle 1 for ATP w/ myosin-ATP hydrolase
⮚ Smooth- no striation b. myosin tail- bundled up together to form
the main bulk of the myosin filament;
contain 1 binding site for actin filaments &
SKELETAL MUSCLES
1 for ATP w/ myosin-ATP hydrolase
- Largest; 10um to 100um to 20cm
⮚ I (Isotropic) band- light bands; composed mainly
- If damaged, they undergo a repair process involving
of bundles of thin actin filaments; shortened and
satellite cells (a population of undifferentiated
disappears in full contraction under ordinary
stem cells) which undergoes mitotic proliferation;
microscope
daughter cells then differentiate into myoblasts;
🡺 Actin filaments- anchored by a network of
myoblasts fuse together to form new fibers or fuse
proteins at the middle called Z line; thin
with stressed or damaged muscle fibers to reinforce
proteins; globular protein consists of a single
and repair them.
polypeptide that polymerizes with other actin
- Tendons: skeletal muscles attached to bones by
monomers to form a polymer made up of two
bundles of connective tissues consisting of collagen
intertwined, helical chains.
fibers. There are short and long tendons.
a. Main body- helical chain of globular actin
molecules forming a bead-like helical
Filament Structures filament; w/ binding sites for myosin
- The striated pattern in skeletal muscle results from heads which is hidden in the helical
the arrangement of cytosolic proteins organized structure (blocked by the tropomyosin)
into two types of filaments distinguished by their when muscle is unstimulated
size and protein composition. b. Tropomyosin- Long proteins that
o Larger: thick filaments; Composition: Myosin intertwine around the globular actin
o Smaller: thin filaments; Composition: Actin filaments; when muscle is stimulated,
tropomyosin is displaced to allow
Myofibrils- cylindrical; long, thin protein-rich fibers exposure of the myosin heads for binding
in each muscle fibers; the dark and light striations of with actin
skeletal muscles is mainly because of these repetitive c. Troponin- globular protein w/ a binding
and light buns along the myofibril’s length; because of site for Calcium; displaces tropomyosin by
the repeated segments (sarcomeres; smallest binding with calcium
contractile segments) along the myofibrils, the muscle
shortens during contraction Cross-bridge cycle
⮚ A (Anisotropic) band- dark, wide bands;
composed of a bundle of thick proteins (Myosin
Muscle Physiology filaments); appear darker in the ordinary
microscope
Muscle- has layers and layers of smaller components 🡺 Myosin filaments- anchored together by a
o Biceps brachi- muscle of the upper arm transecting network of proteins M line or
which is composed of bundles of muscle cells middle disk line); composed of protein
or fiber that are very long. myosin molecules w/ 2 large polypeptide
o Muscle fascicles- bundles of fibers chains & 4 smaller light chains
a. myosin head- cross bridge which forms
3 types of muscle tissues: connection between the myosin filament
⮚ Skeletal- “muscle fiber” due to elongated and actin filament during muscle
shape and presence of multiple nuclei; striated contraction; project perpendicularly;
muscle contain 1 binding site for actin filaments &
⮚ Cardiac- striated muscle 1 for ATP w/ myosin-ATP hydrolase
⮚ Smooth- no striation b. myosin tail- bundled up together to form
the main bulk of the myosin filament;
contain 1 binding site for actin filaments &
SKELETAL MUSCLES
1 for ATP w/ myosin-ATP hydrolase
- Largest; 10um to 100um to 20cm
⮚ I (Isotropic) band- light bands; composed mainly
- If damaged, they undergo a repair process involving
of bundles of thin actin filaments; shortened and
satellite cells (a population of undifferentiated
disappears in full contraction under ordinary
stem cells) which undergoes mitotic proliferation;
microscope
daughter cells then differentiate into myoblasts;
🡺 Actin filaments- anchored by a network of
myoblasts fuse together to form new fibers or fuse
proteins at the middle called Z line; thin
with stressed or damaged muscle fibers to reinforce
proteins; globular protein consists of a single
and repair them.
polypeptide that polymerizes with other actin
- Tendons: skeletal muscles attached to bones by
monomers to form a polymer made up of two
bundles of connective tissues consisting of collagen
intertwined, helical chains.
fibers. There are short and long tendons.
a. Main body- helical chain of globular actin
molecules forming a bead-like helical
Filament Structures filament; w/ binding sites for myosin
- The striated pattern in skeletal muscle results from heads which is hidden in the helical
the arrangement of cytosolic proteins organized structure (blocked by the tropomyosin)
into two types of filaments distinguished by their when muscle is unstimulated
size and protein composition. b. Tropomyosin- Long proteins that
o Larger: thick filaments; Composition: Myosin intertwine around the globular actin
o Smaller: thin filaments; Composition: Actin filaments; when muscle is stimulated,
tropomyosin is displaced to allow
Myofibrils- cylindrical; long, thin protein-rich fibers exposure of the myosin heads for binding
in each muscle fibers; the dark and light striations of with actin
skeletal muscles is mainly because of these repetitive c. Troponin- globular protein w/ a binding
and light buns along the myofibril’s length; because of site for Calcium; displaces tropomyosin by
the repeated segments (sarcomeres; smallest binding with calcium
contractile segments) along the myofibrils, the muscle
shortens during contraction Cross-bridge cycle
⮚ A (Anisotropic) band- dark, wide bands;
composed of a bundle of thick proteins (Myosin
