Muscular System Outline

3 Types of Muscle Tissue 1. Skeletal – Voluntary; responsible for movement. 2. Smooth (Visceral) – Involuntary; movements of respiration, digestion, and urination. 3. Cardiac – Involuntary; heart muscle.

Functions of Muscle Aid in movement Provide and maintain posture Protect internal organs Provide movement of blood, food and waste products throughout the body Open and close body openings Produces heat

Vocab Contraction = movement and shortening of muscle Tonus = slight continuous contraction Flaccid = soft, not contracted

Muscle stimulation 1. Mechanically – You telling your brain to activate a muscle. EX: Holding your pencil to write these notes. 2. Electrically – Using a machine to activate a muscle. EX: IFC in ATR. 3. Chemically – Drugs that activate a muscle. EX: Narcotics will dilate your pupils.

Vocabulary Irritability or excitability: ability to respond to a stimulus Contractility: ability to shorten Extensibility: ability to stretch and lengthen Elasticity: ability to recoil to its resting length

Skeletal Muscle Makes up 40 % of body weight Increase in size and weight with exercise Named according to: ◦Location ◦Related bones ◦Shape ◦Action ◦size Looks striated under microscope (fibers run parallel) Tendons attach muscle to bone

Units of Muscle Fibers Sarcomere: - Causes contraction - Made up of actin and mysosin

3 parts of Skeletal muscle 1. Origin: attached to the less movable part of bone 2. Insertion: attached to the more movable part of the bone 3. Body: middle part of the muscle ◦Also called a ?

Movement Terms Flexion = decreasing joint angle Extension = increasing joint angle Abduction = movement away from midline Adduction = movement towards the midline Pronation = turning palms down Supination = turning palms up

Visceral Muscle Lines organs Makes up walls of blood vessels In the digestive system Smooth – has not striations Contracts when stimulated Controlled by the autonomic nervous system

Cardiac Muscle Only in the heart Striated muscle Involuntary control

Sliding Filament Theory of muscle contraction

Types of Muscle Contraction Isotonic: muscle shortening produces movement through a full range of motion Muscle tone (Tonus) : partial contraction, maintains posture Isometric: no shortening of muscle Tetanic: continued contraction of muscle Fibrillation; uncoordinated contraction of muscle fiber Convulsion; groups of muscles contract in abnormal manner Spasms: involuntary contractions