STUDY GUIDE FOR CHAPTER 6

In addition to the definitions below, see also the summary on pages 191-193,

and the handouts listing individual muscles.

Abduction - movement of a structure away from the midline or central axis; a spreading

Adduction - movement of a structure toward the midline or central axis; opposite of abduction

Acetylcholine - neurotransmitter that initiates muscle contraction by increasing membrane permeability

Actin - protein in muscle tissue that forms thin filaments

Action potential - momentary increase in electrical polarity across a muscle or nerve cell membrane;

in muscle tissue, this leads to an increase in membrane permeability, permitting calcium ions to enter via the T-tubules and pull troponin molecules away from the myosin, initiating contraction

Aerobic respiration - respiration using oxygen, releasing CO₂ and water

Anaerobic respiration (glycolysis) - respiration without use of oxygen, producing lactic acid in muscles

Antagonist - a muscle that pulls in an opposite direction to another. Triceps is an antagonist to biceps.

Aponeurosis - a broad, flat, sheetlike tendon

Belly - the fleshy part of a muscle organ, made of skeletal muscle tissue

Cardiac muscle tissue - involuntary, striated muscle tissue that branches and anastomoses

Creatine phosphate - a chemical that provides phosphate groups to ADP, synthesizing ATP

Depression - a lowering action

Dilation - enlargement of an opening or hollow structure

Dorsiflexion - flexion in a dorsal direction, such as raising of the foot

Endomysium - connective tissue layer around a primary fascicle, continued into the tendon

Epimysium - connective tissue layer around the entire muscle organ, continued into the tendon

Extension - movement straightening a joint

Flexion - movement decreasing the angle of a joint

Insertion - the movable or distal end of a muscle organ

Isometric - a type of contraction in which tension increases because the muscle is unable to shorten

Isotonic - a type of contraction in which a muscle shortens under relatively constant tension

Lactic acid - a chemical (CH₃-CHOH-COOH) produced during anaerobic respiration in muscles; see also oxygen debt

Lateral rotation - outward rotation; clockwise rotation on the right, or counterclockwise on the left

Levation - a rasing action

Ligament - dense, regular connective tissue connecting bone to bone or other non-muscular organs

Medial rotation - inward rotation; clockwise rotation on the left, or counterclockwise on the right

Motor unit - a single motor neuron, plus the muscle fibers that it stimulates

Muscle - an organ containing skeletal muscle tissue, dense regular connective tissue, etc.

Myofibrils - individual fiber units in muscle tissue

Myosin - protein in muscle that forms thick filaments

Neuromuscular junction - contact between a motor neuron and the muscle cell(s) that it activates

Neurotransmitter - a chemical secreted by a neuron, such as acetylcholine

Origin - the fixed or proximal end of a muscle organ

Oxygen debt - build-up of lactic acid during anaerobic conditions, followed by use of oxygen to metabolize the lactic acid when aerobic conditions are restored.

Perimysium - connective tissue layer around of bundle of primary fascicles in a muscle,

continued into the tendon

CONTINUED ON REVERSE SIDE

Plantar flexion - flexion of the foot ventrally (technically, an extension of the ankle joint)

Pronation - medial rotation of the radius upon the ulna

Sarcolemma - the plasma membrane of a muscle fiber

Sarcomere - a unit of contraction in muscle tissue, from one Z-line to the next

Sesamoid bone - a bone such as the patella, formed within connective tissue at a point of stress or friction

Skeletal muscle tissue - voluntary, striated muscle tissue with multinucleated cylindrical fibers

Smooth muscle tissue - involuntary, non-striated muscle tissue occuring in digestive or other organs, but not in muscle organs

Sphinction - constricting of an opening or hollow structure

Supination - lateral rotation of the radius upon the ulna

Synaptic cleft - intercellular space into which a neurotransmitter is secreted

Synergism - action of several muscles working together to help one another

T-tubule (Transverse tubule) - a tube-shaped indentation of the sarcolemma carrying calcium ions to the interior of the muscle fiber

Tendon - a dense, regular connective tissue connecting a muscle belly to bone or other connective tissue

Troponin - a muscle protein that binds to myosin, but binds more strongly to calcium ions