UNIT 3 - Muscular System Flashcards
What are the types of muscle tissue?
The types of muscle tissue are skeletal, cardiac, and smooth muscle. Skeletal muscle is striated and voluntary, cardiac muscle is striated and involuntary, while smooth muscle is non-striated and involuntary.
What are the properties of muscle tissue?
The properties of muscle tissue include contractility, excitability, extensibility, elasticity, and conductivity. Each property plays a crucial role in muscle function.
What are the basic components of muscle cells?
The basic components of muscle cells include the sarcolemma, sarcoplasm, sarcoplasmic reticulum, and myofibrils.
What is the structure of skeletal muscle fibers?
Skeletal muscle fibers are arranged in myofibrils, which are further organized into sarcomeres, T-tubules, and terminal cisternae.
What is the myofilament structure?
The myofilament structure consists of actin (thin filaments), myosin (thick filaments), troponin, tropomyosin, and titin. These proteins are essential for muscle contraction.
What is the organization of a sarcomere?
A sarcomere contains the A band, I band, H zone, Z disc, and M line. Their appearance changes during contraction.
What is the sliding filament mechanism?
The sliding filament mechanism describes how actin and myosin interact to cause muscle shortening.
What are electrically excitable cells?
Electrically excitable cells have a resting membrane potential and utilize ion channels (leak, gated, and voltage-gated) for depolarization and repolarization.
What occurs at the neuromuscular junction (NMJ)?
At the NMJ, components such as the axon terminal, synaptic cleft, and motor end plate facilitate the initiation of muscle contraction.
What is excitation-contraction coupling?
Excitation-contraction coupling is the sequence of events that links the action potential to the sliding of myofilaments.
What is the muscle contraction cycle?
The muscle contraction cycle involves ATP hydrolysis, crossbridge formation, power stroke, and detachment.
How does muscle relaxation occur?
Muscle relaxation occurs as the muscle returns to its resting state, with the role of Acetylcholinesterase being crucial.
What are the energy sources for muscle contraction?
The energy sources for muscle contraction include immediate, glycolytic, and oxidative sources, utilizing ATP, creatine phosphate, glycolysis, and oxidative metabolism.
What are muscle twitch and tetanus?
Muscle twitch includes the latent period, contraction period, and relaxation period, while tetanus can be unfused (incomplete) or fused (complete).
What is the length-tension relationship?
The length-tension relationship describes how the overlap between actin and myosin affects the force of contraction.
What are the classes of skeletal muscle fibers?
The classes of skeletal muscle fibers include Type I (slow oxidative) and Type II (fast glycolytic), with Type II further divided into Type IIa and Type IIx.
What is a motor unit?
A motor unit consists of a motor neuron and all the muscle fibers it innervates, with size affecting muscle control.
What is muscle tone?
Muscle tone refers to the small amount of tension present in a relaxed muscle.
What are the types of contractions?
The types of contractions include isotonic (concentric and eccentric) and isometric.
What is muscle fatigue?
Muscle fatigue is caused by various factors that contribute to a decline in a muscle’s ability to generate force.
What is excess postexercise oxygen consumption (EPOC)?
EPOC refers to the physiological processes that contribute to recovery after exercise.
What is smooth muscle?
Smooth muscle is found in the walls of internal organs, responsible for involuntary movements.
What are muscle actions and terminology?
Muscle actions include terms like ‘abductor’ (pulls away from the midline) and ‘levator’ (raises a body part), each with specific descriptions.
What are muscle origins and insertions?
The origin of a muscle is typically more stationary, while the insertion is the more mobile attachment.
What are the components of a lever system?
A lever system consists of four components: the lever, the force, the load, and the fulcrum.
Describe the structural differences between skeletal, cardiac, and smooth muscle tissues.
Skeletal muscle is striated, multinucleated, and voluntary; cardiac muscle is striated, uninucleated, branched, and involuntary; smooth muscle is non-striated, uninucleated, and involuntary.
Explain how the sliding filament mechanism results in muscle contraction.
The sliding filament mechanism involves myosin heads attaching to actin filaments and pulling them towards the center of the sarcomere, resulting in muscle contraction.
What is the role of calcium ions in excitation-contraction coupling?
Calcium ions bind to troponin, causing tropomyosin to shift and expose the myosin-binding sites on actin, initiating contraction.
Outline the sequence of events that occur at the neuromuscular junction.
An action potential triggers the release of acetylcholine (ACh) into the synaptic cleft, which binds to receptors on the motor end plate, causing depolarization.
What are the three primary energy sources used by muscle fibers during contraction?
The three primary energy sources are immediate (stored ATP and creatine phosphate), glycolytic (anaerobic breakdown of glucose), and oxidative (aerobic metabolism).
How does creatine phosphate contribute to muscle energy supply?
Creatine phosphate donates a phosphate group to ADP, quickly regenerating ATP for short bursts of muscle activity.
Explain the difference between unfused and fused tetanus.
Unfused tetanus allows partial relaxation between stimuli, while fused tetanus results in a smooth, sustained contraction without relaxation.
Describe the length-tension relationship in muscle contraction.
A muscle generates maximum force at an optimal length, allowing for the greatest number of crossbridge formations.
What are the key differences between Type I and Type II muscle fibers?
Type I fibers are slow oxidative and fatigue-resistant, while Type II fibers are fast glycolytic and fatigue quickly.
How does EPOC contribute to post-exercise recovery?
EPOC restores metabolic conditions to resting levels, replenishing oxygen stores and converting lactic acid to glucose.
What is actin?
Actin is a protein that forms the thin filaments in muscle fibers, containing myosin-binding sites for contraction.
What is acetylcholine (ACh)?
Acetylcholine is a neurotransmitter released at the neuromuscular junction that initiates muscle contraction.
What is an action potential?
An action potential is a rapid change in the membrane potential of a cell, triggered by depolarization.
What is the A band?
The A band is the dark band in a sarcomere that contains the entire length of the thick filaments.
What is cardiac muscle?
Cardiac muscle is a type of striated muscle found in the heart, responsible for pumping blood, and is involuntary.
What is creatine phosphate?
Creatine phosphate is a high-energy molecule stored in muscle cells that quickly regenerates ATP.
What is depolarization?
Depolarization is a change in the membrane potential to a less negative value, increasing the likelihood of an action potential.
What is elasticity?
Elasticity is the ability of a muscle fiber to return to its original length after being stretched.
What is endomysium?
Endomysium is the extracellular matrix that surrounds individual muscle fibers.
What is epimysium?
Epimysium is the connective tissue layer that surrounds the entire muscle.
What is excitability?
Excitability is the ability of a muscle fiber to respond to stimuli, such as nerve impulses.
What is excitation-contraction coupling?
Excitation-contraction coupling is the sequence of events linking the action potential to the sliding of myofilaments.
What is extensibility?
Extensibility is the ability of a muscle fiber to be stretched beyond its resting length.
