Guangyuan Pan Period 2 Muscular System
Major function of muscular system
3 types of muscle & function
Skeletal muscles
Sarcomere
Neuromuscular junction
Sliding filament theory of muscle contraction
Action potential in a muscle fiber
Muscle Covering
Smooth
Cardiac
Skeletal
Movement of bones at joints, maintenance of posture
Movement of viscera, peristalsis
Pumping action of the heart
Skeletal muscle
Voluntary
Many nuclei
Well-developed transverse tubule system
lack of transverse tubules
Single nucleus
Wall of hollow viscera, blood vessels
Involuntary
Wall of the heart
single nucleus
Well-developed transverse tubule system; intercalated disc separating adjacent cells.
Incoluntary
Pectoralis major
Deltoid
Extensor digitorum
Biceps brachii
Sternocleidomastoid
External oblique
Large Size
Located in the chest
Shaped like a triangle
named for action
Extends digits
Has 2 origins/heads
found in the arm
attaches to sternum , clavicle, and mastoid process
Fingers, toes
I bands (light bands) aremade up of actin filaments, which are anchored to the Z lines
A bands (dark bands) are made up of overlapping thick and thin filaments
a sarcomereextends from one Z line to the next
in the center of the A band is the H zone, which consists of myosin filaments only
made up of many units called sarcomeres, joined end-to-end
the M line, in the center of the H zone, consists of proteins that hold the myosin filaments in place
located near outside of body
fibers run at a slant
Cell membrane of a muscle fiber is the sarcolemma
Cytoplasm of a muscle cell is the sarcoplasm; it contains many mitochondria and nuclei
Fibers respond to stimulation by contracting
Sarcoplasm contains parallel myofibrils, which are active in
muscle contraction
Each muscle fiber is a single, long, cylindrical muscle cell
Thick filaments in myofibrils consist of the protein myosin
Thin filaments in myofibrils are mainly composed of the protein
actin, but also contain troponinand tropomyosin
the neuron communicates with the muscle fiber by way of chemicals called neurotransmitters, which are released at the synapse
a synapse between a motor neuron and a muscle fiber that it regulates
contract only when stimulated by a motor neuron
myosin heads bind to actin, forming cross-bridges, connecting myosin to acting
the ADP and it releases from myosin and cross-bridge pulls the thin filament
from there the exposed binding sites on actin allow the muscle contraction cycle to start
the new ATP binds to myosin, breaking the connection to actin
muscle contraction releases calcium from the sarcoplasmic reticulum and it exposes binding sites on thin filaments
the ATP splits, which provides power the myosin heads and store energy for the next power stroke.
Prime mover
Pumping action of the heart
Synergist
Movement of viscera, peristalsis, vasoconstriction
Antagonist
Movement of bones at joints, maintenance of posture
the antagonist is the villain to the prime mover, they oppose all the actions from the prime mover
the synergist helps the prime movers and actually supports the prime mover
the prime mover is the function that does most of the work
Fascia
aponeuroses
epimysium
Fascicles
Endomysium
muscles are connected to each other by broad sheets of connective tissue
Layers of dense connective tissue that surround and separate each muscle
the layer of connective tissue around each skeletal muscle
it surrounds bundles of skeletal muscle fibers
Each muscle cell (fiber) is covered by a connective tissue layer