shayan study Flashcards
What is excitability/ irritability in muscles?
Ability to respond to stimuli.
What is contractility in muscles?
Ability to contract and generate force.
What is extensibility in muscles?
Ability to lengthen in response to stimuli
What is elasticity in muscles?
Ability to return to original shape after stretching.
What are the characteristics of smooth muscle?
Involuntary, non-striated, found in organs (e.g., intestines, blood vessels).
What are the characteristics of cardiac muscle?
Involuntary, striated, found in the heart.
What are the characteristics of skeletal muscle?
Voluntary, striated, attached to bones.
What is the parallel arrangement of muscle fibres?
Fibres run along the length (e.g., biceps brachii).
What is the pennate arrangement of muscle fibres?
fibres arranged at oblique angles
(e.g., deltoids).
What is the convergent arrangement of muscle fibres?
Broad origin, fibres converge (e.g., pectoralis major).
What is the circular arrangement of muscle fibres?
Form rings (e.g., around mouth).
What is the muscle belly?
Whole muscle.
What are fascicles?
Bundles of muscle fibres.
What are muscle fibres?
Individual muscle cells.
What are myofibrils?
Contractile elements.
What are myofilaments?
Actin: Thin filament. Myosin: Thick filament.
What is the neuromuscular junction (NMJ)?
Synapse where a motor neuron communicates with a muscle fibre.
What is an action potential?
Electrical impulse that triggers muscle contraction.
What is motor unit recruitment?
Increasing the number of motor units activated for more force.
What is the all-or-none principle?
Muscle fibres in a motor unit contract fully or not at all.
What is the role of ATP in excitation-contraction coupling?
Powers myosin head movement and detachment.
What is myosin ATPase?
Enzyme that breaks down ATP for energy.
What is the role of calcium in muscle contraction?
Binds to troponin, allowing actin-myosin interaction.
What is a powerstroke?
Myosin pulls actin filament, causing contraction.
What is the sliding filament theory?
Myosin heads bind to actin, forming cross-bridges. Myosin pulls actin inward (powerstroke). ATP is required to detach myosin heads and reset the cycle.
What are slow twitch muscle fibres?
High endurance, aerobic, fatigue-resistant. (Marathon runner legs)
What are fast twitch Type IIa muscle fibres?
Intermediate, moderate endurance and power. (Quad’s of Cyclist)
What are fast twitch Type IIb muscle fibres?
High power, anaerobic, fatigues quickly. (Gastrocnemius of sprinter)
What are tonic muscles?
High endurance, postural.
What are phasic muscles?
Quick, powerful movements.
What are the biochemical properties of muscle fibres?
Different fibre types have specific enzymes (e.g., oxidative enzymes in Type I).
What energy systems do muscle fibres rely on?
Type I relies on aerobic metabolism; Type IIb relies on anaerobic glycolysis.
What determines force production in skeletal muscles?
Determined by fibre type and recruitment.
What is the speed of contraction in muscle fibres?
Faster in Type II fibres.
What is fatigue resistance in muscle fibres?
High in Type I fibres.
What is a muscle twitch?
Single contraction from one stimulus.
What is summation in muscle contraction?
Increased force with rapid stimuli.
What is tetanus in muscle contraction?
Sustained contraction with no relaxation.
How is force regulated in muscle?
Motor Unit Recruitment: Activating more units increases force. Frequency of Stimulation: Higher frequency produces greater force. Length-Tension Relationship: Optimal length for maximum force.
What is hypertrophy?
Increase in muscle cell size due to training. (Anabolism)
What is hyperplasia?
Increase in the number of muscle fibre (rare in humans).
What is atrophy?
Decrease in muscle cell size due to inactivity or disease. (Catabolism)
What is the role of a prime mover (agonist)?
Main muscle causing movement.
What is the role of an antagonist?
Opposes the agonist.
What is the role of synergists?
Assist the prime mover.
What is the role of stabilizers (fixators)?
Stabilize a joint during movement.
What is an isometric contraction?
Muscle contracts without changing length. (Hold the dumbbell half way)
What is a concentric contraction?
Muscle shortens during contraction. (Curling a dumbbell up)
What is an eccentric contraction?
Muscle lengthens under tension. (Curling a dumbbell down)
