muscular system (studied)

skeletal muscle

striated; under voluntary control; responsible for producing body movement

cardiac muscle

striated; involuntary; in heart; autrhythmic due to a built-in peacemaker

smooth muscle

attached to hair follicles in skin, in walls of hollow organs/ blood vessels; not striated; involuntary control; regulates organ volumes and movement of substances

functions of muscle tissue

producing body movements

stabilizing body positions

regulating organ volumes

movement of substances within the body

producing heat

what starts muscle contraction?

the release of calcium in the sarcoplasmic reticulum triggers muscle contraction

Neuromuscular junction

synapse between a motor neuron and a muscle fiber

what happens at the neuromuscular junction?

synaptic end bulbs of axon terminals release ACH; ACH binds to receptors on the motor end plate, causing muscle action potential

Sliding filament theory

Calcium binds to troponin, causing tropomyosin to move and expose myosin binding sites on actin. Myosin heads bind to actin, forming cross-bridges, and pill the thin filaments towards the center of the sarcomere, shorening it. ATP is required for the myosin head to detach and reset.