The Immune System

• A complex group of defenses found in the body that fight against harmful substances and pathogens

• Pathogen: infectious agent (or germ) that causes disease or illness in a host

Body Systems involved with Immune System

• Skin

• Respiratory System

• Digestive System

• Circulatory System

–Lymphatic System

First Line Defenses

• Skin: Barrier against pathogens entering the body

• Perspiration and oil gland secretions can make the skin a bad environment for pathogens to grow in

Internal First Line Defense

• Respiratory System– Traps pathogens in cilia and mucus.– Sneezing and coughing can get rid of pathogens.

• Digestive System– Saliva-can kill bacteria.– Stomach, pancreas, and liver-contain enzymes that

can destroy pathogens.– Hydrochloric Acid-kills some bacteria and stops some

virus activity.– Mucus in the digestive tract coats bacteria and keeps

it from sticking to other digestive organs.

Internal First Line Defense (con’t.)

• Circulatory System– White Blood Cells

• Surround and digest foreign organisms and chemicals

• Constantly patrol the body

– Inflammation• Occurs when tissue is injured or becomes infected

– Signs of Inflammation: Redness, increase in temperature, swelling and pain

• Increased blood flow to the area

Specific Immunity

• Antigen-a molecule that is foreign to your body.– Lymphocytes respond to antigens in the body

• Killer T-cells: release enzymes that help destroy undesired matter

• Helper T-cells: activate the immune system and stimulate Blood cells to form antibodies

– Antibody-a protein made in response to a specific antigen

• Makes the antigen useless and more easily caught by Killer T-cells. Or the pathogen can be destroyed.

– Memory B cells-float in blood, waiting to respond to the same pathogen at another time

Active vs. Passive Immunity

• Active Immunity:– The body makes it own antibodies in response to an

antigen– A Pathogen invades and multiplies, making the host

sick.– The body makes antibodies that fight off antigens and

get the host well again.– This is why you only get sick once from some

pathogens, such as Chicken Pox!

• Passive Immunity:– When antibodies that have been produced in another

animal and are introduced into your body.– Last less time that active immunity.

Vaccination

• Vaccine: a form of antigen that gives you active immunity against a disease.

• Vaccination: the process of giving a vaccine by injection or orally (by mouth).

• Helps reduce the risk of childhood disease

• Vaccine can prevent a disease but is not a cure for someone who has contracted and is suffering form a disease.

Tetanus

• Caused by a common soil bacterium.• Can paralyze muscles.

– Sometimes called Lockjaw

• Puncture wounds and deep cuts can easily be infected.

• Children are vaccinated early to build up antibodies against the tetanus toxin.

• Tetanus vaccine also includes booster shots for Diphtheria, a dangerous respiratory disease, and Pertussis or Whooping Cough