Muscle Tissue

Extensibility

Ability to extend

Excitability

Ability to receive and respond to a stimulus

Elasticity

Ability to return to its original shape after contracting or extending

Contractility

Ability to shorten

A band

Area containing thick filaments (includes overlapping thin filaments)

H band

Area with only thick filaments

I band

Area with only thin filaments

Skeletal Muscle Tissue

Attaches to the skeleton, voluntary, striated

Neuromuscular Junction

Axon terminal + Synaptic Cleft + Motor End Plate

M line

Protein in the center of the H band holding thick filaments in place

Z lines

Protein where thin filaments connect

Thin filaments

Protein: actin

Thick filaments

Protein: myosin (protruding portion: crossbridge)

Sarcomeres

Special arrangement of thin and thick filaments, functional unit of the myofibers

Intercalated discs

Special cell junctions unique to cardiac muscle

Motor End Plate

Specialized region of muscle cell membrane under the axon terminal of a motor neuron

Contraction

The sliding filament theory: thin filaments slide inward toward the H band

Action potential

Wave of electrical activity that relays a message down a neuron

Fascia

Broad sheet of connective tissue found beneath skin, around muscles, and around other organs

Aponeurosis

Broad, flat tendon

Motor Nerve

Bundle of axons of motor neurons

Myofibrils

Bundles of thin and thick filaments in the muscle fiber

Sarcolemma

Cell membrane of a muscle fiber

Sarcoplasm

Cytoplasm of a muscle fiber

Fascicle

Distinct bundle of muscle cells (fibers)

Myofibers

Elongated cylinders that lie parallel to each other

Synaptic end bulbs

End of a neuron loaded with neurotransmitters

Sarcoplasmic reticulum

Endoplasmic reticulum of a muscle fiber

Perimysium

Extension of the epimysium that surrounds a fasciculus (or fascicle)

Endomysium

Extension of the perimysium that surrounds individual muscle fibers (cells)

T-Tubules

Extensions of the sarcolemma into the sarcoplasm

Epimysium

Fibrous connective tissue surrounding the outside of a muscle

Deep fascia

Fibrous connective tissue that surrounds individual muscles and muscle groups

Cardiac Muscle Tissue

Forms heart walls, striated, involuntary

Smooth Muscle Tissue

Found in GI tract and urinary tract, involuntary, nonstriated

Smooth Muscle Tissue

Found in digestive/urinary/reproductive organs, nonstriated, involuntary

Cardiac Muscle Tissue

Found in heart walls, involuntary, striated

Guard entrances and exits by forming sphincters around orifices

Function of muscle tissue

Maintain body temperature by generating heat

Function of muscle tissue

Maintenance of posture

Function of muscle tissue

Motion

Function of muscle tissue

Support of soft tissues

Function of muscle tissue

Fast white fibers

High output, fatigue rapidly

Myoglobin

Iron-containing pigment that binds to/stores O2

Triad

T-tubule plus the sarcoplasmic reticulum on each side

Slow red fibers

Lower output, fatigue resistant

Motor Unit

Motor neuron plus all of the muscle cells it stimulates

Blood supplies oxygen and nutrients, both needed for ATP production

Nerve and blood supply to muscle tissue

Neuron

Nerve cell

Motor neuron

Nerve cell innervating a muscle

Motor Nerves

Nerves innervating muscle

Acetylcholine

Neurotransmitter released by synaptic end bulbs of motor neurons

Superficial fascia

Subcutaneous layer, deep to the dermis, covers the entire body, adipose and areolar connective tissue

Muscle Tone

Sustained partial contraction of a portion of a skeletal muscle