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