Three types of muscle tissue o Compare and contrast the three basic types of muscle tissue. • List four characteristics of muscle tissue. • List the functions of muscle tissue • Describe the gross structure of a skeletal muscle. o Organization of muscle, fascicle, muscle fiber, myofibril, myofilaments o Connective tissue sheaths of skeletal muscle: ▪ epimysium, perimysium, and endomysium. o Describe what origins and insertions are in a general terms • Describe the microscopic structure and functional roles of the myofibrils, sarcomere, sarcoplasmic reticulum, and T tubules of skeletal muscle fibers. o Myoglobin, glycosomes o M line, Z disc o Triad • Sliding filament model of muscle contraction • Composition of thick and thin filaments o Structure of Actin, Tropomyosin, Troponin, Myosin • AP, hyperpolarization, depolarization • Ion channel function • Refractory period • Explain how muscle fibers are stimulated to contract by describing events that occur at the neuromuscular junction. • Follow the events of excitation-contraction coupling that lead to cross bridge activity. • Describe cross bridge cycling • Define motor unit and muscle twitch, and describe the events occurring during the three phases of a muscle twitch. • Muscle Atrophy • Explain how smooth, graded contractions of a skeletal muscle are produced. o Temporal summation o Multiple motor unit summation (recruitment) ▪ Know the recruitment thresholds • Differentiate between isometric and isotonic contractions. • Describe three ways in which ATP is generated during skeletal muscle contraction. o Be able to compare and contrast the three modes of ATP generation o Know important molecules (i.e. creatine), whether oxygen is necessary, by-products (i.e. lactic acid) • Define EPOC and muscle fatigue. List possible causes of muscle fatigue. • Describe factors that influence the force, velocity, and duration of skeletal muscle contraction. • Describe the three types of skeletal muscle fibers (slow and fast oxidative, fast glycolytic) • Compare and contrast the effects of aerobic and resistance exercise on skeletal muscles • Compare the gross and microscopic anatomy of smooth muscle cells to that of skeletal muscle cells

Three types of muscle tissue

Skeletal, cardiac, and smooth muscle.

Characteristics of muscle tissue

Excitability, contractility, extensibility, and elasticity.

Functions of muscle tissue

Movement, maintenance of posture, joint stabilization, and heat production.

Gross structure of a skeletal muscle

Organized into muscle, fascicles, muscle fibers, myofibrils, and myofilaments.

Connective tissue sheaths of skeletal muscle

Epimysium (surrounds the muscle), perimysium (surrounds fascicles), and endomysium (surrounds muscle fibers).

Origins and insertions

Origin is the attachment site that remains fixed during muscle contraction; insertion is the attachment site that moves.

Microscopic structure of skeletal muscle fibers

Includes myofibrils, sarcomeres, sarcoplasmic reticulum, and T tubules.

Myoglobin

A protein that binds oxygen in muscle cells.

Glycosomes

Granules of stored glycogen found in muscle cells.

M line

The middle line of the sarcomere where thick filaments are anchored.

Z disc

The boundary structure of the sarcomere where thin filaments attach.

Triad

A structure formed by a T tubule and two adjacent terminal cisternae.

Sliding filament model

Describes how muscle contraction occurs through the sliding of actin and myosin filaments.

Composition of thick and thin filaments

Thick filaments are primarily composed of myosin; thin filaments are primarily composed of actin, tropomyosin, and troponin.

Action potential (AP)

A rapid rise and fall in membrane potential, crucial for muscle contraction.

Hyperpolarization

An increase in membrane potential, making it more negative.

Depolarization

A decrease in membrane potential, making it less negative.

Ion channel function

Regulate the flow of ions across the membrane, essential for generating action potentials.

Refractory period

The time period after an action potential during which a muscle fiber cannot respond to a new stimulus.

Neuromuscular junction

The synapse or junction between a motor neuron and a muscle fiber where stimulation occurs.

Excitation-contraction coupling

The process linking an action potential to muscle contraction through cross-bridge cycling.

Cross bridge cycling

The process by which myosin heads bind to actin filaments and pull them to contract muscle.

Motor unit

A motor neuron and all the muscle fibers it innervates; regulates muscle contraction.

Muscle twitch

A single, rapid contraction and relaxation cycle of a muscle fiber in response to a stimulus.

Phases of a muscle twitch

Latent phase, contraction phase, and relaxation phase.

Muscle atrophy

The wasting or decrease in size of muscle tissue, often due to lack of use.

Smooth, graded contractions

Achieved through mechanisms like temporal summation and multiple motor unit summation.

Temporal summation

Increased muscle tension through repeated stimulation before complete relaxation.

Multiple motor unit summation

Recruitment of additional motor units to increase muscle force.

Recruitment thresholds

The level of stimulation required to activate different motor units.

Isometric contractions

Muscle contractions with no change in muscle length (e.g., holding a weight).

Isotonic contractions

Muscle contractions where muscle shortens or lengthens (e.g., lifting weights).

ATP generation during contraction

Three ways: creatine phosphate, anaerobic glycolysis, and aerobic respiration.

Creatine

A molecule that helps regenerate ATP during short bursts of high-intensity activity.

EPOC

Excess post-exercise oxygen consumption, the amount of oxygen required to restore the body to its resting state after exercise.

Muscle fatigue

A condition characterized by a decline in muscle performance during prolonged activity; causes include depletion of energy stores and accumulation of lactic acid.

Factors influencing muscle contraction

Include muscle fiber type, frequency of stimulation, and energy available.

Types of skeletal muscle fibers

Slow oxidative fibers (Type I), fast oxidative fibers (Type IIa), fast glycolytic fibers (Type IIb).

Aerobic exercise effects

Increases endurance and aerobic capacity of muscles.

Resistance exercise effects

Increases muscle strength and size primarily through hypertrophy.

Smooth muscle cells vs. skeletal muscle cells

Smooth muscle cells are involuntary and non-striated, whereas skeletal muscle cells are voluntary and striated.