Bio Final Exam PDF

LECTURE 10 MUSCLES AND MOVEMENT You're right to check! I missed a few of the terms in the previous response. Here's a comprehensive update with all the vocabulary words you provided, incorporated into the notes in their relevant sections. 1. General Features of Muscle 1.​ Excitability: Muscle...

LECTURE 10 MUSCLES AND MOVEMENT You're right to check! I missed a few of the terms in the previous response. Here's a comprehensive update with all the vocabulary words you provided, incorporated into the notes in their relevant sections. 1. General Features of Muscle 1.​ Excitability: Muscle cells can respond to electrical stimuli (action potentials). 2.​ Contractility: Muscle cells can shorten and generate force. 3.​ Extensibility: Muscle cells can be stretched without damage. 4.​ Elasticity: Muscle cells can return to their original shape after being stretched or contracted. 5.​ Plasticity: Muscle cells can adapt to various lengths and forces depending on usage (e.g., hypertrophy or atrophy). 2. Organization of Vertebrate Skeletal Muscle Skeletal muscle is organized from macro to micro in the following way: 1.​ Whole Muscle: The entire muscle, surrounded by the epimysium, contracts as a unit. 2.​ Fascicle: A bundle of muscle fibers (cells), surrounded by the perimysium. 3.​ Muscle Fiber (Cell): A single muscle cell, surrounded by the endomysium. 4.​ Myofibrils: Long thread-like structures inside muscle fibers, composed of sarcomeres. 5.​ Sarcomeres: The basic contractile units of muscle, consisting of actin (thin filaments) and myosin (thick filaments) arranged in a specific pattern. 6.​ Actin (Thin Filaments) & Myosin (Thick Filaments): These proteins interact during contraction to shorten the sarcomere and generate force. 7.​ Titin: A large protein that helps stabilize myosin filaments and maintain the structure of the sarcomere. 8.​ Tropomyosin: A protein that blocks the binding sites on actin, preventing muscle contraction at rest. 9.​ Troponin: A protein complex that binds to calcium ions and moves tropomyosin, allowing contraction to occur. 3. Nerve and Muscle Connection: Events at the Neuromuscular Junction  1.​ Action Potential: A nerve impulse travels down a motor neuron to the neuromuscular junction. 2.​ Neuromuscular Junction: The synapse (connection) between the motor neuron and the muscle fiber. The neurotransmitter acetylcholine (ACh) is released from the motor neuron and binds to receptors on the muscle cell membrane (sarcolemma). 3.​ Depolarization: Binding of ACh triggers an action potential in the muscle cell, which spreads along the sarcolemma and into the T-tubules. 4.​ Sarcoplasmic Reticulum: The action potential stimulates the sarcoplasmic reticulum (SR) to release calcium ions (Ca²⁺). 5.​ Calcium Binding: Calcium binds to troponin, which causes a conformational change in tropomyosin, exposing binding sites on actin. 6.​ Muscle Contraction: Myosin heads bind to actin, form cross-bridges, and perform a power stroke, sliding the actin filament towards the center of the sarcomere. ATPase on myosin hydrolyzes ATP to provide energy for this movement. 7.​ Relaxation: When the action potential stops, calcium ions are pumped back into the sarcoplasmic reticulum, causing the muscle to relax. 4. Muscle Contraction Cycle ​ Calcium Ions (Ca²⁺): Released from the sarcoplasmic reticulum, binds to troponin. ​ Troponin: Causes tropomyosin to move, exposing the active sites on actin. ​ Actin: Provides binding sites for myosin heads to attach and form cross-bridges. ​ Myosin: Myosin heads bind to actin, undergo a conformational change (power stroke), pulling the actin filament inward. ​ ATPase: Myosin’s ATPase activity provides the energy required for the power stroke and detachment of the myosin head from actin. ​ Sarcoplasmic Reticulum: Actively pumps calcium back into the SR after contraction, causing muscle relaxation. 5. Role of Skeletons in Muscle Function ​ Hydrostatic Skeleton: A fluid-filled cavity provides structural support. In animals like earthworms and jellyfish, fluid pressure helps muscles generate movement. ​ Exoskeleton: A rigid external skeleton (e.g., in arthropods) that muscles attach to for movement. Provides protection and support. ​ Endoskeleton: An internal skeleton (e.g., in vertebrates) made of bone or cartilage, providing structure and support, and allowing muscles to attach and generate movement. ​ Apodemes: Internal ridges in the exoskeleton of arthropods that serve as attachment sites for muscles, aiding in movement. 6. Glycolytic (Fast Twitch) vs. Oxidative (Slow Twitch) Muscle Cells ​ Glycolytic (Fast Twitch) Cells: ○​ Characteristics: Use anaerobic metabolism, generate quick, powerful contractions, but fatigue quickly. ○​ Example Locations: Found in animals requiring bursts of speed or strength, such as sprinters or predators. ​ Oxidative (Slow Twitch) Cells: ○​ Characteristics: Use aerobic metabolism, generate sustained, endurance contractions, and are resistant to fatigue. ○​ Example Locations: Found in animals that need sustained muscle activity, such as long-distance runners or migratory birds. 7. Differences Between Cardiac, Smooth, and Skeletal Muscle ​ Cardiac Muscle: ○​ Structure: Striated, branched, and interconnected by intercalated discs. ○​ Function: Involuntary, rhythmic contractions to pump blood in the heart. ○​ Location: Found in the heart. ​ Smooth Muscle: ○​ Structure: Non-striated, spindle-shaped cells. ○​ Function: Involuntary, controls the movement of substances within hollow organs (e.g., stomach, blood vessels). ○​ Location: Found in walls of internal organs and blood vessels. ​ Skeletal Muscle: ○​ Structure: Striated, long, multinucleated fibers. ○​ Function: Voluntary contractions for movement and posture. ○​ Location: Attached to bones of the skeleton. 8. Muscle Modifications in Animals 1.​ Asynchronous Muscle: Found in some insects (e.g., flies), where muscle fibers contract in a staggered fashion, allowing rapid, continuous movements such as wing beats. 2.​ Flight Muscles: Specialized muscles in birds and insects for rapid and sustained flight. 3.​ Striated Cardiac Muscle: Found in vertebrates, modified to allow for coordinated, rhythmic contraction in the heart. 9. ATP and Muscle Energy Systems ​ Immediate System: Uses ATP and creatine phosphate for quick bursts of energy, providing high-intensity output. ​ Glycolytic System: An anaerobic energy system that uses glycogen to produce ATP, suitable for moderate-duration, high-intensity activities. ​ Oxidative System: An aerobic energy system that uses oxygen to metabolize fats, carbohydrates, and proteins to produce ATP, providing sustained energy for low-intensity, long-duration activities. Vocab 👍 Muscle Fiber: A single muscle cell. Myoblast: Cell that develops into a muscle fiber. Myofibril: Thread-like structures inside muscle fibers, composed of sarcomeres. Actin (Thin Filament): Protein involved in contraction. Myosin (Thick Filament): Protein involved in contraction. Sarcomere: Basic unit of contraction in muscle. Titin: Protein stabilizing myosin filaments. Tropomyosin: Protein that blocks the binding sites on actin. Troponin: Protein complex that moves tropomyosin. ATPase: Enzyme that provides energy for muscle contraction. Contraction Cycle: Series of steps in muscle contraction involving calcium, actin, myosin, and ATP. Action Potential: Electrical impulse that triggers muscle contraction. Neuromuscular Junction: The synapse between motor neurons and muscle fibers. Sarcoplasmic Reticulum: Stores and releases calcium ions. Motor Unit: A motor neuron and the muscle fibers it controls. Hydrostatic Skeleton: Fluid-based skeleton in some animals. Exoskeleton: External skeleton found in arthropods. Endoskeleton: Internal skeleton found in vertebrates. Apodemes: Internal ridges in exoskeletons for muscle attachment. Tendons: Connective tissue attaching muscles to bones. Glycolytic (Fast Twitch) Cells: Muscle fibers that fatigue quickly, generate powerful contractions. Oxidative (Slow Twitch) Cells: Muscle fibers for endurance, resistant to fatigue. Intercalated Discs: Specialized structures in cardiac muscle that allow synchronized contraction. Asynchronous Muscle: Muscle contraction in a staggered pattern (e.g., in insects). Smooth Muscle: Non-striated muscle controlling internal organs. Cardiac Muscle: Striated muscle of the heart. Immediate System: Energy system using stored ATP and creatine phosphate. Glycolytic System: Anaerobic energy system using glycogen. Oxidative System: Aerobic energy system using oxygen to metabolize nutrients