Easy to understand Anatomy & Physiology: Muscles questions & answers

What is the primary function of skeletal muscles? ️☑️ The primary function of skeletal muscles is to produce voluntary movement of the body and maintain posture. Which type of muscle is under voluntary control? ️☑️ Skeletal muscle is under voluntary control. What protein is primarily responsible for muscle contraction? ️☑️ Actin and myosin are the main proteins responsible for muscle contraction. What is the smallest functional unit of a muscle fiber? ️☑️ The sarcomere is the smallest functional unit of a muscle fiber. What structure stores calcium in muscle cells? ️☑️ The sarcoplasmic reticulum stores calcium ions in muscle cells. What is the role of ATP in muscle contraction? ️☑️ ATP provides the energy required for muscle contraction and detachment of myosin from actin. What connects muscle to bone? ️☑️ Tendons connect muscles to bones. What connects bone to bone? ️☑️ Ligaments connect bones to other bones. What is muscle tone? ️☑️ Muscle tone is the continuous partial contraction of muscles to maintain posture. What is a motor unit? ️☑️ A motor unit consists of a motor neuron and all the muscle fibers it controls. What neurotransmitter is released at the neuromuscular junction? ️☑️ Acetylcholine is released at the neuromuscular junction. What is the neuromuscular junction? ️☑️ It is the synapse between a motor neuron and a muscle fiber. 2 What happens during depolarization in muscle cells? ️☑️ Sodium ions enter the cell, making the membrane potential more positive. What triggers muscle contraction? ️☑️ The binding of calcium ions to troponin triggers muscle contraction. What is the role of troponin? ️☑️ Troponin regulates the interaction between actin and myosin by exposing binding sites. What is the sliding filament theory? ️☑️ It describes how actin and myosin filaments slide past each other to shorten the muscle. What is a muscle twitch? ️☑️ A muscle twitch is a single brief contraction and relaxation of a muscle fiber. What are isotonic contractions? ️☑️ Isotonic contractions involve muscle length change with movement. What are isometric contractions? ️☑️ Isometric contractions involve muscle tension without a change in length. What is the difference between concentric and eccentric contraction? ️☑️ Concentric contraction shortens the muscle, while eccentric contraction lengthens it under tension. What type of muscle is found in the heart? ️☑️ Cardiac muscle is found in the heart. What is unique about cardiac muscle cells? ️☑️ They are branched and connected by intercalated discs. What are intercalated discs? ️☑️ They are structures that connect cardiac muscle cells and allow synchronized contraction. What type of muscle is found in the walls of organs? ️☑️ Smooth muscle is found in the walls of organs. Is smooth muscle voluntary or involuntary? ️☑️ Smooth muscle is involuntary. What is the role of mitochondria in muscle cells? ️☑️ Mitochondria produce ATP for muscle contraction. 3 What is muscle fatigue? ️☑️ Muscle fatigue is the reduced ability of a muscle to contract after prolonged activity. What causes muscle fatigue? ️☑️ It is caused by lactic acid buildup, ATP depletion, and ion imbalance. What is oxygen debt? ️☑️ Oxygen debt is the extra oxygen required to restore muscle to resting state after exercise. What is hypertrophy? ️☑️ Hypertrophy is the increase in muscle size due to training. What is atrophy? ️☑️ Atrophy is the decrease in muscle size due to disuse or disease. What is rigor mortis? ️☑️ Rigor mortis is the stiffening of muscles after death due to lack of ATP. What is the role of calcium in muscle contraction? ️☑️ Calcium binds to troponin to initiate contraction. What is the all-or-none principle? ️☑️ A muscle fiber contracts fully or not at all when stimulated. What is muscle recruitment? ️☑️ Muscle recruitment is the activation of more motor units to increase force. What determines muscle strength? ️☑️ Muscle strength depends on the number of motor units recruited and muscle fiber size. What are fast-twitch muscle fibers? ️☑️ Fast-twitch fibers contract quickly but fatigue rapidly. What are slow-twitch muscle fibers? ️☑️ Slow-twitch fibers contract slowly and are resistant to fatigue. What is the role of myoglobin? ️☑️ Myoglobin stores oxygen in muscle cells. What is the endomysium? ️☑️ It is a connective tissue layer surrounding individual muscle fibers. What is the perimysium? ️☑️ It surrounds bundles of muscle fibers called fascicles. 4 What is the epimysium? ️☑️ It surrounds the entire muscle. What is a fascicle? ️☑️ A fascicle is a bundle of muscle fibers. What is the sarcolemma? ️☑️ It is the plasma membrane of a muscle cell. What is the sarcoplasm? ️☑️ It is the cytoplasm of a muscle cell.