Chapter 1: Musculoskeletal system Flashcards
Muscles can only ____ not ___ through the system of bony levers
Pull, not push
Axial skeletons consists of (4)
skull, cerebral column, ribs, and sternum
Appendicular skeleton consists of (4)
shoulder, UE bones, pelvic girdle, LE bones
Fibrous joints: consist of, allows…
sutures of skull, no movement
Cartilaginous joints: consist of, allows…
intervertebral disks, limited movement
synovial joints: consist of, allows…
elbow and knee, considerable movement
What is special about synovial joints
used in most sport and exercise movements due to low friction and large ROM.
Articulating bone ends are covered with ___ and the entire joint is enclosed in a capsule filled with ____. They support ___ and ___.
hyaline cartilage
synovial fluid
ligament and cartilage
Uniaxial joints: body part, operate as, how many axis
elbow
hinges
one axis
Biaxial joints: body part, how many axis
ankle and wrist, 2 axis
Multiaxial joints: body part, operate as, how many axis
shoulder, hip, ball and socket, 3 axes
Fibrous connective tissue
epimysium
Where is the tendon attached to and what does it do?
Bone periosteum, during contraction, themuscle pulls on the tendon and in turn, the bone.
Muscle fibers layers from superficial to deep
Epimysium, fasciculus (150 muscle fibers) surrounded by perimysium, muscle fiber each surrounded by endomysium, under endomysium is sarcolemma aka fibers membrane.
All connective tissue (epi,peri, endomysium) is contiguous with
Tendon
Motor neuron and muscle fibers it innervates are called
motor unit
Sarcoplasm is
cytoplasm of a muscle fiber
What dominates the sarcoplasm and what does it contain?
Myofibrils, contain the myofilaments that contracts the muscle cells: myosin and actin
How myosin interacts with actin
Myosin filaments form a cross bridge
How myosin and actin organized
Longitudinally win the smallest contractile unit of skeletal muscle, the sarcomere
Adjacent myosin filaments anchor to each other at the
M bridge in the center of the sarcomere/ center of H zone.
Actin filaments are anchored at the
Z line
A band is what color and corresponds with
Dark, the alignment of myosin
I band is what color and corresponds with
light, the areas in two adjacent sarcomeres that contain only actin filaments
Z line is located at
middle of I band
H zone located at and have only what filaments
center of the sarcomere, myosin filament
During muscle contraction, what happens to the H zone
H zone decreases as actin slides over myosin toward the center of the sarcomere
During muscle contraction, what happen to the I bands
Decreases as the Z lines are pulled towards the center of the sarcomere
Sarcoplasmic reticulum and what does it vesicles contain and its role
Tubules surrounding each myofibril, vesicles contain calcium ions which controls muscle contraction
T tubules: location and its role in muscle contraction
perpendicular to sarcoplasmic reticulum. Being contigous to sarcolemma at the surface of the cell allows action portential from motor nerve signals, releasing calcium into the sarcoplasmic reticulum into the myofibril, causing tension development in muscle.
Sliding filament theory
actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling Z lines towards center of sarcomere, thus shortening the muscle fiber.
What is responsible for movement of actin filament and how many is needed
Myosin crossbridges pulling the actin filaments. Multiple rapid flexions from many crossbridges to allow measurable actin movment to occur.
Resting phase
Little calcium is president in myofibril and most are stored in sarcoplasmic reticulum.
Excitation contraction coupling phase
Sarcoplasmic reticulum release calcium ions, which binds to troponin protein along the actin filament. This causes a shift to the tropmyosin protein. Now the myosin crossbridge attaches to the actin filament to be pulled toward the center to the sarcomere.
The amount of force produced by a muscle at any instant is related to
The number of myosin crossbridges bound to actin filaments at that instant in time
Contraction phase: where does the energy of the pulling action/power stroke comes from
Breakdown/hydrolysis of ATP to ADP and phosphate, catalyzed by the ATPase enzyme. Another ATP molecule replace the ADP on the myosin crossbridge globular head, allowing the head to detact from active actin site and return to its original position, allowing contractions to continue.
Recharge phase: occurs as long as (3)
calcium is available in the myofibril, ATP is available to assist uncoupling the myosin from actin, and sufficient myosin ATPase to catalyzing ATP breakdown.
Relaxation phase
Calcium is pumped back to sarcoplasmic reticulum, preventing the link between actin and myosin thereby returning their filaments to their unbound state.
