Chapter 10 Flashcards
What are the three types of muscle tissue?
Skeletal muscle, Cardiac muscle, Smooth muscle.
What is excitability in muscle cells?
Responsiveness of muscle cells.
What is contractility?
Ability of muscle cells to shorten.
What is extensibility?
Ability of muscle cells to stretch.
What is elasticity in muscle cells?
Ability of muscle cells to recoil.
What are the functions of skeletal muscle?
Producing movement, maintaining posture and body position, supporting soft tissues, guarding body entrances and exits, maintaining body temperature, storing nutrients.
What do skeletal muscles contain?
Skeletal muscle tissue (primarily), connective tissues, blood vessels, and nerves.
What is the epimysium?
Layer of collagen fibers that surrounds the entire muscle, connected to deep fascia, separating muscle from surrounding tissues and organs.
What is the perimysium?
Divides the skeletal muscle into series of compartments, surrounds muscle fiber bundles (fascicles), contains collagen fibers, elastic fibers, blood vessels, and nerves.
What is the endomysium?
Surrounds individual muscle cells (muscle fibers), contains capillary networks, myosatellite cells, and nerve fibers.
What is a tendon?
Bundle formed by collagen fibers of epimysium, perimysium, and endomysium at the ends of muscles to attach skeletal muscles to bones.
What is an aponeurosis?
Broad sheet formed by collagen fibers of epimysium, perimysium, and endomysium at the ends of muscles to attach skeletal muscles to bones.
What are skeletal muscle fibers?
Are enormous compared to other cells, contain hundreds of nuclei, develop by fusion of embryonic cells (myoblasts), and are known as striated muscle cells due to striations.
What is a sarcomere?
Repeating functional units formed by the arrangement of thin (actin) and thick (myosin) filaments in skeletal muscle fibers.
What is a myosatellite cell?
Stem cell that helps repair damaged muscle tissue.
What is the sarcolemma?
Plasma membrane of a muscle fiber that surrounds the sarcoplasm.
What is sarcoplasm?
Cytoplasm of a muscle fiber.
What is a myofibril?
Long contractile fibers within a muscle fiber responsible for muscle contraction.
What are transverse tubules (T tubules)?
Narrow tubes that are continuous with the sarcolemma and extend deep into the sarcoplasm, transmitting action potentials from sarcolemma into cell interior.
What is the sarcoplasmic reticulum (SR)?
A tubular network surrounding each myofibril, specialized for storage and release of calcium ions.
What is a triad?
Formed by two terminal cisternae plus a T tubule.
What are thin filaments primarily composed of?
Actin (protein).
What are thick filaments primarily composed of?
Myosin (protein).
What are voluntary muscles?
Muscles that contract only when stimulated by the central nervous system.
How does the diaphragm function?
Usually works subconsciously.
What do mitochondria do?
Organelles producing ATP through cellular respiration.
What is the role of troponin?
Protein regulating actin-myosin interaction.
What is the sliding-filament theory?
Theory explaining muscle contraction mechanism.
What is the zone of overlap?
Region where thick and thin filaments overlap.
What is an active site?
Binding site on G-actin for myosin.
What is F-actin?
Filamentous actin composed of G-actin subunits.
What is a motor neuron?
CNS neurons that stimulate skeletal muscle fibers.
What are action potentials?
Electrical impulses that trigger muscle contractions.
What is the neuromuscular junction (NMJ)?
Site of communication between neuron and muscle fiber.
What is acetylcholine (ACh)?
Neurotransmitter released at the NMJ for muscle activation.
What is exocytosis?
Process of neurotransmitter release into the synaptic cleft.
What is the synaptic cleft?
Space between axon terminal and muscle fiber.
What are T tubules?
Extensions of sarcolemma penetrating muscle fiber.
What is cross-bridge formation?
Binding of myosin heads to exposed active sites on actin.
What is the power stroke?
Myosin head pivoting action that pulls actin filaments.
What is the contraction cycle?
Series of events enabling muscle contraction via cross-bridges.
What is myosin reactivation?
Process of myosin head re-cocking after ATP hydrolysis.
What is muscle tension?
Force generated by muscle contraction against resistance.
What does the duration of contraction depend on?
Neural stimulus, calcium presence, and ATP.
What triggers muscle contraction?
Calcium ion release by binding to troponin.
What is active-site exposure?
Uncovering of actin sites for myosin binding.
What is cross-bridge detachment?
Breaking of link between myosin and actin.
What is a skeletal muscle fiber?
Striated muscle cells responsible for voluntary movement.
What does AChE do?
Enzyme that breaks down acetylcholine after muscle activation.
What is cytosol?
Fluid component of the cytoplasm where reactions occur.
What is sarcomere shortening?
Process where muscle fibers contract and shorten.
What is ATP availability?
Essential for sustaining muscle contraction cycles.
What is neural control?
Regulation of muscle contraction by motor neuron signals.
What happens during skeletal muscle relaxation?
Occurs when calcium is reabsorbed and ACh is degraded.
What are Ca2+ ions?
Calcium ions crucial for muscle contraction initiation.
What are active sites?
Binding sites on actin for myosin attachment.
What is tension production?
Force generated by muscle fibers during contraction.
What is a myogram?
Graph depicting muscle tension over time.
What is a twitch?
Single muscle contraction in response to stimulation.
What is the latent period?
Time between stimulus and muscle contraction onset.
What is the contraction phase?
Period when muscle tension increases and peaks.
What is the relaxation phase?
Period when muscle tension decreases post-contraction.
What is a motor unit?
Motor neuron and all muscle fibers it controls.
What is muscle tone?
Normal resting tension in muscles at rest.
What is isotonic contraction?
Muscle changes length while producing tension.
What is isometric contraction?
Muscle develops tension without changing length.
What is the load-speed relationship?
Heavier loads slow down muscle contraction speed.
What are elastic forces?
Tendons help return muscles to resting length.
What is ATP?
Primary energy source for muscle contractions.
What is creatine phosphate?
Energy reserve that recharges ADP to ATP.
What is glycolysis?
Anaerobic breakdown of glucose for ATP production.
What is aerobic metabolism?
Oxygen-dependent ATP production in mitochondria.
What is lactic acidosis?
Condition from increased lactate during intense activity.
What is creatine kinase?
Enzyme that catalyzes ATP and creatine reactions.
What is muscle relaxation?
Muscle returns to resting length post-contraction.
What are energy reserves?
Stored ATP, glycogen, and creatine phosphate in muscles.
What is sustained contraction?
Requires repeated stimuli for continuous muscle activity.
What are opposing muscle contractions?
Muscles that help return a muscle to resting length.
What is muscle fiber activity?
Energy required for regular muscle function.
What are fatty acids?
Primary energy source for resting muscle metabolism.
What is glycogen?
Stored glucose for energy during muscle activity.
What is pyruvate?
Product of glycolysis, converted to lactate under stress.
What is lactate?
Produced from pyruvate during anaerobic conditions.
What do hydrogen ions (H+) do?
Increase cytosolic acidity, inhibit muscle contraction.
What is the recovery period?
Time for muscles to return to normal post-exertion.
What is oxygen debt?
Increased oxygen need after exercise for recovery.
What is heat production in muscles?
Skeletal muscles release heat, maintaining body temperature.
What does muscle performance depend on?
Depends on muscle fiber type and conditioning.
What are fast fibers?
Contract quickly, fatigue rapidly, few mitochondria.
What are slow fibers?
Contract slowly, high endurance, many mitochondria.
What are intermediate fibers?
Mid-sized, fatigue slower than fast fibers.
What is muscle hypertrophy?
Growth from training, increasing fiber diameter.
What is muscle atrophy?
Reduction in muscle size due to inactivity.
What is cardiac muscle tissue?
Striated tissue in the heart, involuntary contractions.
What are intercalated discs?
Connections between cardiac cells for synchronized contraction.
What is smooth muscle tissue?
Non-striated, involuntary muscle in internal organs.
What is excitation-contraction coupling?
Calcium triggers contraction in smooth muscle.
What is plasticity in smooth muscle?
Smooth muscle’s ability to function over varied lengths.
What is the Cori cycle?
Lactate conversion to glucose in the liver.
What are muscle fiber types?
Fast, slow, and intermediate fibers vary in function.
What is endurance?
Time an activity can be sustained effectively.
What is force in muscle physiology?
Maximum tension produced by muscle fibers.
What is aerobic endurance?
Sustained activity supported by oxygen and mitochondria.
What is anaerobic endurance?
Short bursts of activity using fast fibers.
What is myoglobin?
Oxygen-binding protein in slow muscle fibers.
What is fibrosis?
Increase in fibrous tissue with aging.
