PSY290H1 Lecture Notes - Lecture 6: Sarcomere, Cranial Nerves, Autonomic Nervous System
Document Summary
Motor neurons in ventral horns of spinal cord. Action potential signals travel to the muscles through ventral roots. Acetylcholine (ach) is released at the motor neurons-muscle synapses (neuromuscular junction) Released ach binds to receptors on muscle fiber, postsynaptic potentials arise and trigger aps in muscle fibers. Ach receptors on the muscle fibers are the nicotinic ach receptors (nachr)- ionotropic receptors. Nachr activation produces psps in the muscle. Same rules of spatial and temporal summation are applied: the signals above the threshold trigger the opening of voltage-gated sodium channels: neuromuscular junction: site of ach release. Muscle is attached to bones through the tendons. Each muscle is a bundle of muscle fibers (myofiber) Each muscle fiber is a single, very long cell with multiple nuclei. Each muscle fiber contains multiple cylinder-shaped bundles of protein polymers called myofibrils. Dynamic change in the structure of these protein polymers is a key to muscle contraction.
