Defenses - Science

YOUR DEFENSE SYSTEM

• A pathogen is an organism, a virus, or a protein that causes disease.
• EXTERNAL DEFENSES - Your skin provides external protection against pathogens that may enter the body. Skin also has structures, such as hair, nails, and sweat and oil glands, that help provide protection. Nails protect your fingertips and toes. The skin and all of these structures make up the integumentary system.
• INTERNAL DEFENSES - Most of the time, pathogens cannot get past external defenses. Blood flow increases to the injured area, causing it to swell and turn red. This swelling and redness is called inflammation. Cell pieces in the blood, called platelets, help seal the open wound so that no more pathogens can enter. Your body may also respond by raising your body temperature. This response is called fever, which slows the growth of bacteria and some other pathogens. Both inflammation and fever are a part of the body's internal defense. The immune system is made up of tissues and specialized white blood cells that recognize and attack foreign substances in the body.

How does the body build immunity ?

• Immunity is the ability to resist or recover from an infectious disease. Immunity is passed from a mother to her fetus.
• MEMORY CELLS - Once your body has fought a pathogen, the body produces memory cells. Memory cells are T cells and B cells that "remember" a specific pathogen.
• VACCINATION - A vaccine is a substance prepared from killed or weakened pathogens that is introduced into the body to produce immunity. The vaccine stimulates the body to make an immune response. Vaccination, or immunization, is a way to prevent illness from some disease.

CHALLENGES TO THE IMMUNE SYSTEM

• ALLERGIES - An immune system reaction to a harmless or common substance is called an allergy. Allergies can be caused by certain foods such as peanut, medicines such as penicillin, or certain types of pollen and molds.
• CANCER - Cancer is a group of diseases in which cells divide at an uncontrolled rated. Skin cancer is often caused by exposure to ultraviolet rays from sunlight, which can affect the cells that make pigment.
• IMMUNE DEFICIENCY - The immune system sometimes fails to develop properly or becomes weakened, resulting in an immune deficiency disorder. Acquired immune deficiency disorder. Acquired immune defi