Lesson 13: Muscular System

Sarcoma

("sarc-" tissue) cancers that affect the body's soft tissue; more common in children and young adults. Mostly malignancies in skeletal muscle, rhabdomyosarcoma. Treatment: three-pronged; surgery, chemo, radiation

Muscle spasm vs. cramp

*Spasm: involuntary contraction (usually facial or eyelids, triggered by anxiety or other psycho-emotional cause) *Cramp: muscle spasm that doesn't immediately release (usually calf and thigh, triggered by low potassium which is needed for proper transmission of nerve impulses)

Muscular System parts and functions

*Triceps brachii: straightens forearm at elbow. *Biceps brachii: bends the forearm at the elbow. *Deltoid: raises the arm. *Pectoralis major: draws the arm forward and in toward the body. *Trapezius: lifts shoulder blade, braces the shoulder, draws the head back. *Serratus anterior: draws shoulder blade forward, helps raise arm, assists in pushes. *External oblique: compresses the abdomen, assists in lateral rotation of the trunk. Latissimus dorsi: rotates and draws the arm backward and toward the body. *Rectus abdominis: depresses the thoracic (chest) cavity, compresses the abdomen, bends the backbone. *Adductor longus: flexes, laterally rotates, and draws the thighs toward the body. *Gluteus maximus: extends and rotates the thigh outward when walking, running, and climbing. *Sartorius: bends the thigh at the hip, bends lower leg at the knee, rotates the thigh in an outward direction. *Biceps femoris: (hamstring muscle) draws thigh backward, bends the knee. *Quadriceps femoris: flexes the thigh at hips, extends the leg at the knee. *Gastrocnemius: bends the lower leg at the knee when walking, extends the foot when jumping. *Tibialis anterior: flexes the foot toward the shin.

Exercise focus

-A sprinter will trigger fast muscle fibers in the thighs. -A swimmer will trigger the mitochondria in the shoulder muscle fibers.

Skeletal muscle types

1) Slow-twitch red fibers contain a lot of myoglobin (protein that binds oxygen for ATP production), lots of blood vessels, helps you keep your posture, stronger muscles (some back and leg.) 2) Fast-twitch white fibers have less myoglobin and less mitochondria, contract rapidly and powerfully for short periods, and include the muscles in your hand.

Tetanus

A bacteria that travels to the spinal cord where in blocks nervous system signals that release skeletal muscles from contraction. Muscles go into spastic paralysis, fists and jaw may stay clenched, and spine may arch in a stiff curve. Treatment: immunity by vaccine in childhood and booster in adulthood

Bursa

A fluid-filled sac that a tendon slides inside to reduce the friction of a tendon rubbing against a bone. In some cases a bursa is elongated into a tendon sheath that folds around the tendon (like in your knees, wrists, and fingers.)

Duchenne muscular dystrophy

A single mutated gene that interferes with the ability of sarcomeres to contract; most common in children, usually in wheelchair by teens and die by early twenties.

Tendon

A strap of dense CT that attaches a muscle to a bone or another muscle; help make joints more stable by helping keep the adjoining bones properly aligned.

Describe how the Muscular System contributes to the function of the whole body.

Bones and 600+ skeletal muscles work like a system of levers in which bones (rigid rods) move near joints (fixed points). When a muscle contracts it pulls on the bones that it's attached to - muscles are usually attached very close to most joints. *Origin: the end of the muscle that is attached to the motionless bone. *Insertion: the end of the muscle that is attached to the bone that moves the most.

Muscular System

Consists of skeletal muscles, tendons that connect muscles to bones, and ligaments that attach bones together to form joints.

Skeletal muscle

Function: as muscles contract, they pull on skeletal bones that then move the body. Structure: long, cylindrical, multinucleated cells. -Cells/muscle fibers are made up of myrofibrials (myro refers to skeletal muscle) which contract the muscle fiber. -Banded or striated appearance reflects the arrangement of the myofilaments. -Skeletal muscles are voluntary muscles. Location: attached to the bones of the skeleton; most common type of muscle tissue.

Cardiac muscle

Function: as the cardiac muscle tissue contracts, it propels blood through the blood vessels and throughout the body. Structure: striated but differs from skeletal muscle because cardiac cells are uninucleate and the cells are branched cells that fit together at junctions called intercalated discs. -Contract as a single unit. -Cardiac muscle is involuntary muscle. Location: the wall of the heart.

Botulinum toxin

Inhibits ACh release (the neurotransmitter that triggers muscle contractions), muscles become paralyzed (heart and skeletal breathing muscles) Treatment: quick antitoxin

Myopathy

Muscle disease; muscle disorder

Synergist muscles

Muscles working together; helpers of prime mover.

Myotonic muscular dystrophy

Not life-threatening and generally effects the feet and the hands by muscles strongly contracting and don't relax in a normal way; more common in adults.

Antagonistic muscles

One muscles reverses the action of the other muscle (biceps & triceps.)

Muscular distrophies

Part of a large group of genetic diseases in which skeletal muscle fibers break down, resulting in whole muscles shriveled and weakened.

Muscle strain

Stretching or tearing of muscle fibers, usually some bleeding in the damaged area causing swelling and a painful muscle spasm. Treatment: ice pack, resting the muscle, anti-inflammatory drugs

Smooth muscle

Structure: non-striated -cells are spindle shaped and contain a single, central nucleus. -cells linked by junctions and are often organized into sheets. -smooth muscle is an involuntary muscle. Location: in the walls of hollow organs of the digestive and urinary tract organs, the uterus, and blood vessels.

Muscular System & homeostasis

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