Muscular System Flashcards
Origin
one end of skeletal muscle joins to a bone that remains mostly stationary
Insertion
other end of muscle that attaches to another bone across a joint
Myofibril
very fine contractile fibers, groups of which extend in parallel columns along the length of striated muscle fibers
Sarcomere
the fundamental repeat unit within muscle that is responsible for contraction; consists of myosin-containing thick filaments + actin-containing thin filaments.
Motor neuron
cells in the brain and spinal cord that allow movement, speech, swallowing, and breathing by sending commands from the brain to the muscles that carry out said functions
Neurotransmitter
chemical messengers; carry chemical signals from one neuron (nerve cell) to the next target cell (another nerve cell, a muscle cell, gland)
Neuromuscular junction
a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/smooth/cardiac). Site for the transmission of action potential from nerve to the muscle.
Latent period
delay between the receipt of a stimulus by a sensory nerve and the response to it.
Contraction
presence of calcium permits contraction: myosin and actin slide past each other, shortening the sarcomere; known as the sliding filament mechanism).
Relaxation
muscles are no longer stimulated by a nerve
ATP
energy-carrying molecule found in the cells of all living organisms
Isotonic
a muscle shortens while maintaining a constant force
Isometric
tension is generated, but bones do not move; neither does the body
Motor unit
the motor neuron + muscle cells it controls
Muscle tension
of muscle cells in each motor unit (motor unit size), # of motor units active @ any one time, frequency of stimulation of individual motor units.
