Fascia

Layer of fibrous connective

tissue that encloses a muscle

Tendon

Cordlike or bandlike mass of dense connective tissue that connects a muscle to a bone

Aponeuroses

Sheet of connective tissue that attaches muscles to bone and other muscles

Muscle

Organs composed of specialized cells that use the chemical energy stores in nutrients to exert a puling force on structures to which they are attached

Epimysium

Layer of connective tissue that closely surounds a skeletal muscle

Perimysium

Layer of connective tissue that extends inward from the epimysium and separates the muscle tissue into small sections

Fascicles

Bundles of skeletal muscle fibers

Endomysium

Layer of connective tissue in the form of a thin covering that fascicles lie in

Deep fascia

Portion of the network that surrounds the muscles

Subcutaneous fascia

Lies just beneath the skin and forms the subcutaneous layer

Subserous fascia

Forms the connective tissue later of the serous membrances covering organs in various body cavities and lining of them

Myofibrils

Any of the thread-like bundles of filaments in muscle cells

Thick Filaments

Composed of the protein myosin

Thin filaments

Composed of the protein actin

Myosin

Protein that, with actin, causes muscle contraction

Actin

A protein in a muscle fiber that forms the thin filaments that slide between filaments of the protein myosin, shortening the muscle fibers

Sarcomere

Structual and functional unit of a myofibril

Titin

Protein that attaches myosin filaments to z lines in muscle

Troponin

Protein that functions with tropomyosin to block muscle contraction until calcium ions are present

Tropomyosin

Protein that blocks muscle contraction until calcium ions are present

Sarcoplasmic reticulum

Membranous network of channels and tubules in a muscle fiber, corresponding to the endoplasmic reticulum of other cells

Transverse tubules (T-tubules)

Membranous channel that extends deep into the cell from a muscle fiber membrane

Cisternae

Enlarged portion of the sarcoplasmic reticulum near the actin and myosin filaments of a muscle fiber

Triad

Group of three structures; in muscle, two cristanae and a transverse tubule

Synapse

Functional connection between the axon of one neuron and the dendrite or cell body of another neuron or a membrane of another cell type

Neurotransmiters

Chemical that an axon end secretes into a synapse

Motor neurons

Neuron that conducts impulses from the central nervous system to an effector

Neuromuscular junction

Synapse between a motor neuron and a skeletal muscle fiber; myoneural junction  

Motor end plate

Specialized part of a muscle fiber membrane at a neuromuscular junction

Synaptic cleft

A narrow extracellular space between the cells at a synapse

Acetylcholine (ACh)

Type of nuerotransmiter, which is a biochemical secreted at the axon end of neurons and which acts on the postsynaptic cell, ACH 

Sliding filament model

Muscles shorten when the thin (actin) and thick (myosin) filaments slide past eachother pulling on the muscle ends

ATPase

Enzyme that transfers the energy stored in terminal phosphate bonds of ATP molecules

Acetylcholinesterase

Enzyme that catalyzes breakdown of acetylcholine

Creatine phosphate

Molecule in muscle that stores energy

Myoglobin

Oxygen storing pigment in muscle tissue

Lactic Acid Threshold

A shift in metabolism where anaerobic reactions break down glucose into pyruvic acid, which then reacts to produce lactic acid