Muscular System Flashcards
Skeletal muscle
Attaches to bone, causes movement of body. Voluntary because it can be contracted at will. Strained. Consists of bundles of tiny fibers that run the length of the muscle.
Endomysium
Delicate connective tissue that covers each muscle fiber
Fascicles
Muscle fibers are grouped in bundles.
Epimysium
Another layer of connective tissue, surrounds muscle as a whole and binds all the muscle fibers together.
How does muscle attach to muscle?
Indirect attachment- the epimysium extends past the muscle as a flat broad tendon and attaches to another muscle.
Tendons
Strong connective tissue. In indirect attachment, the epimysium extends past the muscle as a tendon. The tendon then murres with the periosteum.
Myofibrils
Long protein bundles that fill the sarcoplasm. They store glycogen (which is used for energy) as well as oxygen.
T Tubules
A system of tubules that extend across the sarcoplasm formed from inward projections of the sarcolemma. The tubules allow electrical impulses to travel deep into the cell.
Sarcromeres
Section between the z-discs. This is where muscle contraction occurs
Sliding filament model
As the sac Romero shortens, so does the myofibril and the entire muscle. Myofilaments do not shorten, they stay the same. The sacromeres shorten because the filaments slide over the top of one another.
Muscle contractions require this to occur
ATP and calcium
Sequence of events in muscle contraction
The impulse triggers the release of ACh which defuses across the synaptic cleft, to stimulate the T-tubules to replace calcium which binds with troponin in the on the acton filaments who’ve permits the myosin heads to latch on to the actin.
Myasthenia gravis
Autoimmune disorder characterized by extreme muscle fatigue. Women affected more than men. Usually begins around middle age. Autoantibodies destroy acetylcholine receptors. Cannot cause depolarization of muscle fibers. Causes trouble swallowing.
What does the force of muscle contraction depend on?
Strength, stretch, number of fibers, and size
Incomplete tetanus
When impulses reach the muscle fibers very fast, the fibers dont have time to relax completely before the next impulse arrives. Condition of rapid contraction.
