뒤로Anatomy & Physiology Exam 3 Review: Muscle Tissue and Skeletal Muscles
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The three muscle types are skeletal, cardiac, and smooth muscle, differing in structure and function.
Excitability, contractility, extensibility, and elasticity.
The sarcomere is the basic contractile unit of a muscle fiber, composed of thick and thin filaments between two Z discs.
It explains muscle contraction by thin filaments sliding past thick filaments, shortening the sarcomere without changing filament length.
The SR stores calcium ions and releases them to trigger contraction; T tubules conduct action potentials deep into muscle fibers.
A motor unit consists of a single motor neuron and all the muscle fibers it innervates.
The neuromuscular junction is the synapse where a motor neuron communicates with a muscle fiber to initiate contraction.
ACh is the neurotransmitter released at the neuromuscular junction to stimulate muscle contraction.
Depolarization is the change in membrane potential making the inside of the sarcolemma more positive, triggering an action potential.
Repolarization restores the resting negative membrane potential after depolarization.
It is the process linking the action potential in the muscle fiber to calcium release and muscle contraction via the sliding filament mechanism.
Calcium binds to troponin, causing tropomyosin to move and expose binding sites on actin for myosin, enabling contraction.
Concentric contractions shorten the muscle; eccentric contractions lengthen the muscle while generating force.
A muscle twitch is a single, brief contraction and relaxation cycle in a muscle fiber.
Variations in muscle contraction strength due to changes in stimulus frequency or stimulus strength, including incomplete and complete tetanus.
ATP is generated by direct phosphorylation, anaerobic glycolysis, and aerobic respiration.
Muscle fibers differ as slow oxidative, fast oxidative, and fast glycolytic, based on contraction speed and metabolism.
Smooth muscle uses calmodulin instead of troponin and contracts via a similar sliding filament mechanism but is involuntary and slower.
A gap junction allows direct electrical communication between adjacent cardiac or smooth muscle cells for coordinated contraction.
Muscle tone is the continuous, passive partial contraction of muscles to maintain posture and readiness.
Sarcopenia is the age-related loss of muscle mass and strength.
Origin is the fixed attachment point; insertion is the movable attachment point of a muscle.
Muscles are named based on location, shape, size, direction of fibers, number of origins, and action.
A fascicle is a bundle of muscle fibers surrounded by connective tissue.
Fascicles can be parallel, fusiform, circular, pennate (uni-, bi-, multi-), each affecting muscle function.
The diaphragm is the main muscle of inspiration, increasing thoracic volume to draw air into the lungs.
The masseter, temporalis, medial, and lateral pterygoids are key muscles for chewing.
It is the ability of smooth muscle to stretch and then relax to accommodate volume changes without contracting.