Muscle Tissue Characteristics Flashcards

Types of Muscle Tissue

• Three main types: skeletal, cardiac, smooth.

Skeletal Muscle

• Voluntary control, attached to skeleton.
• Cells are cylindrical, multinucleate, and arranged in parallel.
• Striated appearance due to organized protein filaments.
• Does not replicate; lacks centrioles.

Cardiac Muscle

• Found exclusively in the heart.
• Cells are short, branched, with a single nucleus.
• Interconnect at intercalated disks featuring ion channels.
• Striated and involuntary; cells are physically and functionally synchronized.

Smooth Muscle

• Located in the walls of organs and blood vessels.
• Lacks striations, classified as non-striated and involuntary.
• Extensible properties, allowing for dynamic shape alterations like in the bladder.
• Capable of replication.

Characteristics of Muscle Tissue

• Four key properties: excitability, contractility, extensibility, elasticity.

Endomysium

• Connective tissue that surrounds individual skeletal muscle fibers, binding adjacent fibers together.

Fascicle

• A bundle of muscle fibers held together by endomysium.

Perimysium

• Connective tissue that surrounds each fascicle.

Epimysium

• Dense layer of collagen fibers encasing the entire muscle.

Tendon and Aponeurosis

• Tendons are dense regular connective tissue formed from bundled collagen fibers of all muscle layers; aponeurosis is a flat sheet form.

Sarcolemma

• Membrane surrounding muscle fibers, serving as a barrier for ion movement.

T Tubules

• Narrow tubules filled with extracellular fluid; form a network that extends into muscle fibers.

Function of T Tubules

• Conduct electrical pulses from the sarcolemma, triggering muscle contractions by altering internal chemical environment.

Myofibrils

• Cylindrical structures composed of protein strands, spanning the length of muscle fibers.
• Each fiber contains hundreds to thousands of myofibrils, made up of bundles of thick and thin myofilaments.

Myofilaments

• Composed of thin filaments (actin) and thick filaments (myosin), integral to muscle contraction and structure.

Sarcoplasmic Reticulum

• Specialized endoplasmic reticulum that forms a tubular network around each myofibril, storing calcium ions.

Terminal Cisternae

• Located on either side of T tubules, forming triads with myofibrils.
• High concentration of calcium ions stored here; release initiates muscle contraction.