Muscular Tissue

Sarcolemma

The plasma membrane of a muscle cell that transmits electrical signals.

Sarcoplasm

The cytoplasm of a muscle cell that contains cellular components.

Sarcoplasmic reticulum

A structure that stores calcium with terminal cisternae at the ends and surrounds myofibrils.

Mitochondria

Organelles that are important for aerobic respiration and the generation of ATP.

T-tubules

Structures that connect the sarcolemma to the terminal cisterna and conduct electrical signals inward.

Myofibrils

Bundles of contractile proteins within muscle fibers.

Myofilaments

Contractile proteins in muscle fibers, divided into thick (myosin) and thin (actin) filaments.

Z discs

Structures that define the boundaries of sarcomeres.

A bands

Dark bands in a muscle fiber where thick and thin filaments overlap.

I bands

Light bands in a muscle fiber where only thin filaments exist.

H bands

Lighter middle region of the A band where only thick filaments exist.

Endomysium

Connective tissue that surrounds individual muscle cells.

Perimysium

Connective tissue that surrounds fascicles (bundles of muscle cells).

Epimysium

Connective tissue that surrounds the entire muscle.

Isometric contraction

A type of contraction where tension changes but length remains constant.

Isotonic contraction

A type of contraction where length changes but tension remains constant.

Skeletal muscle

Type of muscle that is voluntary and operates under conscious control.

Cardiac and smooth muscles

Types of muscles that are involuntary and function without conscious control.

Slow twitch muscle fibers

Muscle fibers designed for stamina and endurance, utilizing aerobic respiration.

Fast twitch muscle fibers

Muscle fibers designed for strength and speed, utilizing anaerobic respiration.

Threshold

The minimum voltage needed to stimulate a neuron to fire, important for muscle recruitment.

Treppe

Increased tension with a moderate frequency increase in nervous stimulus.

Incomplete tetanus

A state where muscles have insufficient time to fully relax between contractions.

Complete tetanus

A state of no relaxation between contractions, leading to sustained maximum contraction.

Action potential

A rapid voltage change across the membrane crucial for muscle contraction.

Aerobic respiration

A process that requires oxygen and yields 36 ATP per glucose molecule with water and CO2 as by-products.

Fermentation (anaerobic)

A process that does not require oxygen, yielding only 2 ATP per glucose molecule, leading to lactic acid buildup.

Sarcoplasmic reticulum functions

Regulates calcium ion concentration within muscle cells and is essential for muscle contraction.

Muscle fatigue causes

Includes ATP synthesis decline, lactic acid buildup, and depletion of neurotransmitters.

Refractory period

The period immediately following an action potential during which the neuron cannot fire another action potential.

Latent period

The time between stimulus and tension development in a muscle twitch.

Contraction phase

The phase during a muscle twitch where tension increases.

Relaxation phase

The longest phase of a muscle twitch where tension decreases.

Myofilament proteins functions

Includes actin forming thin filaments, myosin forming thick filaments, troponin regulating contraction, and tropomyosin covering binding sites.

Rigor mortis

The stiffening of muscles after death due to lack of ATP and calcium release.

Phosphagen system

A rapid energy system using creatine phosphate to regenerate ATP in the first 10 seconds of high-intensity activity.