A tissue in the center of some bones.

A type of connecting tissue that holds bones to other bones at the joint.

A strong, flexible tissue that allows joints to move easily, cushions bones, and supports soft tissues.

A type of connecting tissue that joins muscles to bones and muscles to muscles.

Tissues that move parts of the body and control the organs.

The body's message and control center.

The command center, or coordinator, of the nervous system.

Cells that make up the nervous system.

The brain and the spinal cord.

The nerves that connect the central nervous system to all parts of the body.

A long bundle of neurons that sends messages to and from the brain and all parts of the body.

The part of the nervous system that deals with actions that you control.

The part of the nervous system that deals with actions you do not usually control.

The group of organs and tissues that carry needed materials to cells and remove their waste products.

Organs and tissues that transport essential materials to body cells and remove their waste products.

The muscle that acts as the pump for the circulatory system.

Blood vessels that carry blood away from the heart to various parts of the body.

Blood vessels that carry blood from all parts of the body back to the heart.

Tiny blood vessels that carry blood to and from almost all body cells and connect arteries and veins.

Process in which the body's cells are nourished and energized.

When blood travels from the heart through the lungs, and back to the heart.

When oxygen-rich blood travels to all body tissues except the lungs.

The yellowish, watery part of blood.

The organs that supply your blood with oxygen.

Two large organs that exchange oxygen and carbon dioxide.

The exchange of gases between your body and the air.

The upper part of the respiratory system, which contains the vocal cords.

A passageway in your throat that takes air into and out of your lungs.

A flap of tissue in the back of your mouth that keeps food out of your trachea.

Two passageways that branch from the trachea, one to each lung.

A large, dome-shaped muscle below the lungs that expands and compresses the lungs, enabling breathing.

A measure of ozone, sulfur dioxide, carbon monoxide and fine particles close to the ground.

The group of organs that work together to break down foods into substances that your cells can use.

The process the body uses to get rid of waste.

A digestive juice produced by the salivary glands in your mouth.

Substances that aid in the body's chemical reactions.

The process by which the body breaks down food into smaller pieces that can be absorbed by the blood and sent to each cell in your body.

A coiled tube from 20 to 23 feet long in which about 90 percent of digestion takes place.

A digestive gland that secretes a substance called bile, which helps to digest fats.

A small, saclike organ that stores bile.

A gland that helps the small intestine by producing pancreatic juice, a blend of enzymes that breaks down proteins, carbohydrates, and fats.

The group of organs that work together to remove wastes.

Organs that remove waste material, including salts, from the blood.

A tube five to six feet in length that plays a part in both digestion and excretion.

An open sore in the stomach lining.

A combination of body defenses made up of the cells, tissues, and organs that fight pathogens in the body.

The ability to resist the pathogens that cause a particular diseases.

The body's response to injury or disease, resulting in a condition of swelling, pain, heat and redness.

A secondary circulatory system that helps the body fight pathogens and maintains its fluid balance.

Special white blood cells in the lymphatic system.

Substances that send the immune system into action.

Proteins that attach to antigens keeping them from harming the body.

A preparation of dead or weakened pathogens that is introduced into the body to cause an immune response.