unit 1 Flashcards
study for test
skeletal muscle major functions
force production for locomotion and breathing (movement)
force production for postural support
heat production for maintenance of body temperature (shivering/normal muscle contractions)
anatomy of skeletal muscle
whole muscle, fascicles, muscle fibers/muscle cells, myofibrils, contractile proteins organized into sarcomeres
whole muscle is surrounded by connective tissue called
epimysium
whole muscles are made up of bundles of
Fascicles
fascicles are surrounded by connective tissue called
perimysium
fascices are made up of
muscle fibers/muscle cells
muscle fibers/muscle cells are surrounded by connective tissue called…
endomysium
muscle fiber/ muscle cells are made up of
myofibrils that contain contractile proteins
What do myofibrils contain?
contractile proteins (actin and myosin)
myofibrils have how many nucleus
multi-nucleated
what is the muscle cell membrane?
sarcolemma
What do transverse tubules (T tubules) do?
signal from nervous tissue gets to sarcoplasmic reticulum
continuous with membrane
extends from sarcolemma to sarcoplasmic reticulum
what does the sarcoplasmic reticulum do?
web like structure that is the storage site for calcium
terminal cisternae
what does calcium do in muscle fibers?
signal for muscle to contract
what are the parts that make up myofibril?
sarcomere -> actin/myosin
z line to Z line is
1 sarcomere
Myosin is
thick filament
polymer of 200 myosin molecules; two stands
heads protrude from thick filament axis and interact with actin filaments
has head, body, neck
actin is
think filament
two strands of actin wrap around each other
tropomyosin
protein that covers myosin binding sites
troponin
protein attached to tropomyosin that pulls it away from binding site when bound to calcium
titin
stabilizes myosin along longitudinal axis, largest protein in the body,
involved with increased force during eccentric (stretching or lengthening) contractions
Nebulin
anchoring protein for actin
sliding filament model
muscle shortening due to overlap of myosin and actin
this overlapping creates a cross-bridge and overall creates a power stroke
reduces distance between z lines of sarcomere
Resting position of sliding filament model
tropomyosin is in place blocking myosin binding sites on actin
ATP is bound to myosin, ATPase hydrolyzes ATP into ADP, P, and energy
myosin filament is in high energy state
myosin head is “cocked” - ready to bind/move