Muscles Flashcards
What are the three layers of connective tissues wrappings found in a skeletal muscle?
Epimysium, perimysium, endomysium
What is the structure and function of a muscle fiber?
Muscle fibers are elongated cells that contract to produce movement
What is a fascicle in skeletal muscle?
A bundle of muscle fibers
What is the structural unit of a muscle fiber responsible for contraction?
Myofibril
What is a sarcomere?
The basic contractile unit of a muscle fiber
What do thick filaments primarily contain?
Myosin proteins
What do thin filaments primarily contain?
Actin proteins
What is the sarcolemma?
The cell membrane of a muscle fiber
What is the function of the sarcoplasmic reticulum?
Storage and release of calcium ions
What is a t-tubule?
A tubular extension of the sarcolemma that penetrates into the muscle fiber
Why are skeletal muscles striated?
Due to the organized arrangement of myofibrils and sarcomeres
What is the structure of the neuromuscular junction?
The synapse between a motor neuron and a muscle fiber
What is the process of excitation-contraction coupling?
The mechanism linking muscle excitation to contraction
Why does the opening of acetylcholine receptors depolarize the sarcolemma?
It allows Na+ ions to enter the muscle fiber
What is the sliding filament model of skeletal muscle contraction?
The theory that muscle fibers contract by sliding thick and thin filaments past each other
What is cross-bridge cycling?
The process by which myosin heads attach to and pull on actin filaments
What roles do Ca2+, troponin, and tropomyosin play in muscle contraction?
Ca2+ binds to troponin, causing tropomyosin to move and expose binding sites on actin
What is the process of muscle relaxation?
Calcium ions are pumped back into the sarcoplasmic reticulum, and myosin heads detach from actin
Define motor unit.
A motor neuron and all the muscle fibers it innervates
What is a muscle twitch?
A single, rapid contraction and relaxation of a muscle fiber
What is tetanus in muscle physiology?
A sustained muscle contraction due to high-frequency stimulation
How can different levels of contraction be produced?
By controlling muscle fiber recruitment and frequency of neural stimulation
What are the types of muscle contractions?
Isometric, isotonic concentric, isotonic eccentric
When does isometric contraction occur?
When muscle tension increases but muscle length does not change
When does isotonic concentric contraction occur?
When muscle shortens while generating force
When does isotonic eccentric contraction occur?
When muscle lengthens while generating force
What are the three ways ATP is made in skeletal muscle cells?
Creatine phosphate, anaerobic respiration, aerobic respiration
How does ATP production differ during different types of exercise?
Intensity and duration of exercise affect the primary energy pathways used
What are fast twitch muscle fibers?
Muscle fibers that contract quickly and fatigue rapidly
What are slow twitch muscle fibers?
Muscle fibers that contract slowly and are resistant to fatigue
What are the circular and longitudinal layers of smooth muscle?
Circular layers constrict the lumen, longitudinal layers shorten the organ
What is the basic structure of smooth muscle cells?
Spindle-shaped, non-striated cells with a single nucleus
How do skeletal and smooth muscle differ?
Skeletal muscle is striated and voluntary; smooth muscle is non-striated and involuntary
