38 cards
Skeletal muscle
A type of muscle tissue that is attached to bones and enables voluntary movement
Smooth muscle
Involuntary muscle tissue found in walls of internal organs and blood vessels
Cardiac muscle
Involuntary muscle tissue found only in the heart
Sarcomere
The basic contractile unit of muscle fiber
Actin
A thin filament protein in muscle fibers that interacts with myosin for muscle contraction
Myosin
A thick filament protein that interacts with actin for muscle contraction
Neuromuscular junction
The synapse between a motor neuron and a skeletal muscle fiber
Acetylcholine
Neurotransmitter released at the neuromuscular junction to stimulate muscle contraction
Sliding filament theory
The process by which actin and myosin filaments slide over each other during muscle contraction
Tendons
Connective tissues that attach muscles to bones
Ligaments
Connective tissues that connect bones to other bones
Motor unit
A single motor neuron and all the muscle fibers it innervates
Muscle hypertrophy
An increase in muscle size due to an increase in the size of individual muscle fibers
Muscle atrophy
A decrease in muscle mass due to disuse or denervation
Isometric contraction
Muscle contraction without a change in muscle length
Isotonic contraction
Muscle contraction with a change in muscle length
Fast-twitch fibers
Muscle fibers that contract quickly and generate high force but fatigue rapidly
Slow-twitch fibers
Muscle fibers that contract slowly and are resistant to fatigue
Glycolysis
A metabolic pathway that converts glucose into pyruvate, providing energy for muscle contractions
Creatine phosphate
A molecule that can quickly donate a phosphate to ADP to regenerate ATP in muscle cells
What is the role of calcium in muscle contraction?
Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from actin's myosin-binding sites, allowing contraction.
Troponin
A protein complex involved in muscle contraction that binds calcium ions
Tropomyosin
A protein that blocks myosin-binding sites on actin molecules in resting muscle
Rigor mortis
A postmortem condition where muscles become stiff due to the lack of ATP required to release myosin from actin
ATP's role in muscle contraction
ATP binds to myosin, allowing it to detach from actin and re-cock for another power stroke
Endomysium
Connective tissue surrounding individual muscle fibers
Perimysium
Connective tissue surrounding a bundle of muscle fibers (fascicle)
Epimysium
Connective tissue surrounding an entire muscle
What is muscle fatigue?
The decline in ability of a muscle to generate force, often due to prolonged activity, lack of energy, or accumulation of metabolic byproducts.
Myoglobin
An oxygen-binding protein in muscle cells that provides a reserve of oxygen for aerobic ATP production
What is the function of the sarcoplasmic reticulum?
The sarcoplasmic reticulum stores calcium ions and releases them upon stimulation to initiate muscle contraction.
Muscle spindle
A sensory receptor located in muscles that senses changes in muscle length
Golgi tendon organ
A sensory receptor located at the junction of a muscle and its tendon, sensitive to changes in muscle tension
Fascicle
A bundle of skeletal muscle fibers surrounded by perimysium
What is the all-or-none principle in muscle contraction?
A muscle fiber will contract to its full potential when stimulated; there is no partial contraction.
Origin of a muscle
The fixed attachment point of a muscle, typically proximal
Insertion of a muscle
The movable attachment point of a muscle, typically distal
What is the role of ATPase in muscle contraction?
ATPase is an enzyme on the myosin head that hydrolyzes ATP, providing energy for the power stroke during contraction.
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