A. LOCOMOTION. The interaction of muscles with the skeleton causes body movements is known as locomotion. Locomotion increases the chances for survival of an organism by allowing the organism to gather food, seek shelter, and escape dangerous situations. Locomotion also increases the chances for survival of a species by enabling members of the species to find suitable mates. Human locomotion involves the interaction of joints and tissues such as bone, cartilage, muscles, tendons and ligaments.

Advantages of locomotion. Allows organism to gather food, seek shelter, escape dangerous situations, find suitable mates.

B. BONES. Bone is a type of connective tissue. It is composed of relatively few cells surrounded by large amounts of a hard intracellular material. The intracellular material is composed mainly of calcium compounds. The hardness of the bone is due to th presence of calcium and phosphorus minerals. Bones make up the major part of the framework of the human endoskeleton and come in many shapes and sizes. Bones support and protect body organs. They also provide a place for muscle attachment. Periosteum

The bones of your legs and arms are called long bones. The ends are covered with cartilage and are capable of growth. The outer covering is a tough membrane called the Periosteum. Long bones contain living blood, fat, and bone cells. Red and white blood cells are produced in the inner tissue, called marrow, of some bones.


Functions of the human skeletal system.

It acts as a framework for supporting other organs of the body. It also protects internal organs and allows body movement.

CARTILAGE. The fibrous, flexible, elastic connective tissue found in the human skeleton is cartilage. In the human embryo, the skeleton is made up mostly of cartilage. By adulthood, most of the cartilage has been replaced by bone. In the adult, cartilage is found in the nose, ears, and trachea, at the ends of ribs and other bones, and between the vertebrae. At the ends of bones, cartilage provides flexibility. Between bones, cartilage provides cushioning. In the ears, nose, and trachea, cartilage provides flexible, rather than rigid, support.

What is cartilage?

Fibrous, flexible, elastic connective tissue found in the human skeleton

Three places in the human where cartilage is found.

Nose, ears, and trachea, at the ends of ribs and other bones, and between the vertebrae.

How does cartilage change from the embryo stage to adulthood. Most of the cartilage has been replaced by bone

E. JOINTS. Bones are connected at places called joints. Most joints allow bone movement. Ball and socket joints are located at the hip and shoulder. They permit circular movement. Hinge joints are located at the elbows and knees. They allow a back and forth movement. Hinge joints do not permit as much movement as ball and socket joints. Pivot joints are found where the skull joins the vertebral column. Pivot joints permit a rotating movement. The wrist and ankle have gliding joints that allow a sliding action. Fused joints are not movable and are located in the skull. Fluids in joints help keep joints cushioned and lubricated.

 How many bones are in the human skeleton? 206

An endoskeleton is an           inner    skeleton.

NAME OF JOINT                  LOCATION                FUNCTION

ball and socket             hip and shoulder                       circular movement

hinge joint                     elbows and knees                     back and forth movement

pivot joints                    skull                                         rotating movement

gliding joints                  wrist and ankle             sliding action

fused joints                   skull                                         no movement

MUSCLES. The human body contains three kinds of

cardiac muscle            smooth muscle skeletal muscle

Muscles produce body movement by pulling on bones when they contract. Muscles also produce body heat when they contract. Muscles can be voluntary or involuntary.

INVOLUNTARY MUSCLES. Involuntary muscles are responsible for involuntary body activities such as heart contractions and peristalsis. You cannot control the actions of involuntary muscles. Smooth muscle and cardiac muscle are examples of involuntary muscles.

Smooth muscle is found in the walls of arteries and organs of the body. Contraction of smooth muscle is controlled by the nervous system. Cardiac muscle, found in the walls of the heart. causes the heart to beat.


controlled for locomotion. Skeletal muscles are attached to the bones of the skeleton. The bones and body parts are moved by the contraction of these muscles. Skeletal muscles usually function in opposite pairs. One muscle of the pair is an extensor, which extends (straightens) the limb. The other muscle is a flexor, which bends the limb. The biceps and triceps of the upper arm are an example of a pair of muscles that function in this way (Figure 13-5). The bicep, a flexor, is located on the front of the upper arm. When the

bicep contracts, the forearm is pulled toward the front of the shoulder causing the arm to bend. The tricep, an extensor, is located on the back of the upper arm. When the tricep contracts, the arm straightens out.

MUSCLE ACTION Nerves direct impulses to muscles causing them to contract. The

energy needed for the muscle to contract comes from energy stored in chemicals such as glycogen. Muscle cells will continue to operate even if they do not receive sufficient oxygen. When the muscle does not receive enough oxygen to carry on aerobic respiration, the muscle cells change to anaerobic respiration. During anaerobic respiration they produce lactic acid. Lactic acid causes muscles to hurt. This condition is known as muscle fatigue. Rest after exercise supplies oxygen to fatigued muscle cells. During this rest-recovery period, the lactic acid is removed and energy-storing compounds are built up again. If a person does not rest after muscle fatigue, permanent injury to the muscle can occur.

TENDONS AND LIGAMENTS. Tendons and ligaments are both composed of connective tissue. Tendons are bands of dense tissue that connect muscles to bones. Ligaments are tough bands of tissue that hold bones together at joints.

MUSCLE-BONE DISORDERS Some disorders of the musculoskeictal system are fractures, hernias, sprains, arthritis and tendonitis.

Fractures. Fractures are broken hones. The bone is usually broken directly across its width, but can also be broken lengthwise, or spirally. Fractures can be closed (simple or open (compound). In a closed fracture the broken hone ends stay under the skin and little or no surrounding skin and tissues are damaged. In an open fracture, one or both hone ends stick out through the skin. Fractures are caused by a sudden injury that exerts more force on the bone than it can support. The common symptom of a fracture is swelling and tenderness at the place of the fracture. In some eases, the bone ends are deformed or stick out. Pain is often severe and is usually made worse by any movement of the area. Anyone suffering a suspected or known fracture should he taken to a hospital. Do not try Lu force the bone back into place.

Sprains. A tearing or stretching of the ligaments that hold together the bone end in a joint is called a sprain. Sprains arc caused by a sudden pull or twist. The main symptoms of a sprain are pain and tenderness in the affected area and rapid swelling. Sometimes there is d of the skin and an inability to use the joint. Because a sprain and a fracture have similar symptoms, the sprain should be x-rayed to be sure that it is not a fracture. Treat a sprain by applying an ice pack to reduce swelling, wrapping the joint with a compression bandage, and resting it in a raised position until the pain and swelling begin to drop. Take aspirin or other pain killers to relieve pain.

Hernias. In a hernia an organ or tissue sticks out through a weak area in the muscle or other tissue that usually contains it such as the abdominal wall. The cause is usually a weakness in the wall The first symptom is a bulge in the wall. Treat by wearing a supportive garment or truss. In severe cases, surgery is performed.

Arthritis. An inflammation of the joints is called arthritis. Arthritis causes stiffness, swelling, soreness, or pain. Osteoarthritis is a type of arthritis that results from wear and tear on the cartilage at the joints Rheumatoid arthritis causes swelling and pain and can occur at any age. Sometimes the joints stiffen in a deformed position. Cortisone and other medications are used on the treatment of arthritis.

Tendonitis is an inflammation of a tendon, usually at the bone junction. Usually pain is felt in the wrist or ankle after extensive use such as running or even using a computer. This condition is common in athletes