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 weightIncrease in size and weight with exerciseNamed 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 angleExtension = increasing joint angleAbduction = movement away from

midlineAdduction = movement towards the

midlinePronation = turning palms downSupination = 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

Sliding Filament Theory of muscle contraction

Types of Muscle ContractionIsotonic: 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