The Muscular System Working out: keeping the body functioning

THE PURPOSE OF OUR MUSCLES Some muscles work with the skeleton to allow the body to move. Some muscles work automatically to control functions like digestion and breathing. Some muscles never get tired and keep working our entire life.

MUSCLE TISSUE The only tissue that is able to contract. Muscle tissue is made up of individual muscle cells called fibers. The function of a muscle fiber is to contract completely. Muscles only do work when they contract.

MUSCLE TISSUE Muscle tissue consists of cells that have the ability to contract and exert as pulling force.

3 TYPES OF MUSCLE TISSUE Skeletal muscle: attached to bones Smooth muscle: make up the walls of internal organs and blood vessels Cardiac muscle: found only in the heart.

TYPES OF MUSCLE COMPARISONS Controls the involuntary beating of the heart. Involuntary not under conscious control Striated, looks like a woven rug CARDIAC Controls the automatic, involuntary movements like breathing and digestion. Involuntary not under conscious control Not striped or striated SMOOTH Moves the parts of the body including the skeleton Locomotion Voluntary under conscious control Striped or striated SKELETAL or STRIATED MOVEMENTCONTROLAPPEARANCE MUSCLE TYPE

SKELETAL MUSCLE It is striated. Fibers are organized in parallel rows. Skeletal muscle is voluntary. We have conscious control over them Skeletal muscles are attached to bones by tendons They are responsible for movement of body parts. Skeletal muscles fatigues (tires) easily.

SMOOTH MUSCLE Smooth muscle appears to be smooth in appearance when viewed with the naked eye. Layers of smooth muscle are found in the walls of our internal organs and blood vessels.

SMOOTH MUSCLE Smooth muscle is involuntary. We do not have control of them. Contraction of these muscles is controlled by the nervous system automatically and unconsciously. Smooth muscle fatigues slowly

CARDIAC MUSCLE Cardiac muscle looks like a woven rug. Cardiac muscle is only found in the HEART. Cardiac muscle is involuntary Cardiac muscle does not fatigue.

CARDIAC MUSCLE Contracts and relaxes continuously throughout life. Under its own internal controls, producing the regular beating action of the heart.

How SKELETAL MUSCLES work To produce movement of a bone muscles always work in pairs. One muscle of the pair will contract (flexor), while the other muscle of the pair relaxes (extensor). To produce the opposite movement the first muscle (flexor) relaxes and the second muscle (extensor) contracts

How SKELETAL MUSCLES work The Biceps muscle (A) is an example of a flexor. It will bend the lower arm up and towards the body. The Triceps muscle (B) is an example of an extensor. It straightens the arm. Muscle fatigue: buildup of lactic Acid in muscle fibers during hard exercise

How SKELETAL MUSCLES work Skeletal muscles only do work by contracting. Skeletal muscles pull on bones to make them move. Skeletal muscles always work in pairs. Individual muscle fibers always contract completely. Muscle fibers only contract when stimulated by a nerve.

How SKELETAL MUSCLES work Skeletal muscles are made up of hundreds of individual muscle fibers. The strength of a muscle’s contraction is determined by the number of individual fibers that contract at the same time. The more muscle fibers contracting at the same time, the stronger the total muscle contraction.