Muscular System #1 Flashcards
What is the function of the muscular sytem?
Movement, Posture, Heat production
What do muscles help move?
Skeleton, Internal organs, Heart
What are muscles?
Muscular tissue held together by connective tissue
What attaches the muscle to the bone?
Tendons
What are aponeurosis.
a sheet of pearly white fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment
What makes up a muscle fiber?
Sarcolemma, sarcoplasm, myofibrils, sarcomere, and myofilaments (actin, myosin)
What is sarcolemma?
a specialized membrane which surrounds striated muscle fiber cells.
What is sarcoplasm?
the cytoplasm of striated muscle cells
What are myofibrils?
very fine contractile fibers, groups of which extend in parallel columns along the length of striated muscle fibers. The myofibrils are made up of thick and thin myofilaments, which help give the muscle its striped appearance
What is sarcomere?
the functional unit of striated muscle
What are myofilaments?
the filaments of myofibrils, constructed from proteins, principally myosin or actin
What is actin?
a protein that forms the contractile filaments of muscle cells, thin
What is myosin?
a protein that forms the contractile filaments of muscle cells, thick
What is a myosatellite cell?
differentiate and fuse to augment existing muscle fibers and to form new fibers
What is an I band?
Light band, only has thin filaments and is found between the A bands, centered around the Z line (border between sarcomere)
What is an A band?
Dark band, has both thin and thick filaments
What is an M line?
A line down the A bands comprised of multiple M enzymes responsible for energy metabolism
What is the H zone?
Area of A band with only thick filaments
How do myosin and actin work together?
Myosin heads bind to the actin and pull on it, which is the sliding filament theory
How does a muscle contract?
a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber. When all the sarcomeres in a muscle fiber shorten, the fiber contracts.
What other proteins are contained in actin?
Tropomyosin, Troponin
What does tropomyosin do?
changes position to reveal actin attachment sites when calcium binds to troponin
What does troponin do?
Binding site for calcium, causing movement in tropomyosin when bound to calcium
What does calcium do in the muscles?
Calcium binds to the troponin, causing a position change in tropomyosin, exposing the actin sites that myosin will attach to for a muscle contraction
What is the sarcoplasmic reticulum?
a complex network of specialized smooth endoplasmic reticulum that is important in transmitting the electrical impulse as well as in the storage of calcium ions
How does a sarcomere shorten?
the actin is pulled along myosin toward the center of the sarcomere until the actin and myosin filaments are completely overlapped
What is the neuromuscular junction?
is a synaptic connection between the terminal end of a motor nerve and a muscle
What is the motor end plate?
specialized chemical synapses formed at the sites where the terminal branches of the axon of a motor neuron contact a target muscle cell
What neurotransmitter activates muscles?
acetylcholine
What is depolarizaiton?
Na enters the cell, K leaves the cell, changing the membrane potential and continuing the AP down the fiber/nerve
What is rigor mortis?
Rigor mortis is defined by the decline of ATP to zero, 0% extensibility, an ultimate pH that is reached, and the production of lactic acid that has plateaued.
What is related to muscle fiber contraction strength?
Nerve impulse stays the same, more calcium can cause a stronger contraction, fatigue in muscles results in weaker contractions
What is an isometric contraction?
A muscular contraction in which the length of the muscle does not change
What is an isotonic contraction?
A muscular contraction in which the length of the muscle changes
