Immune System

Protection against Pathogens

• Diseases are caused by microorganisms.• Microorganism – tiny living things,

many one celled–Called Pathogens

Lines of Defense

• Body has 2 lines of defense–First = keeps pathogens out–Second = detects and destroys

pathogens

First Line of Defense

• Skin = barrier between your body and the environment–Keeps pathogens

OUT

• Sweat Glands EXCRETE salts that help kill bacteria on skin

• Tears wash pathogens out of eyes–Also contain salt

• Nose hair filters pathogens out of the air you inhale.

• Mucus and cilia trap also trap pathogens.

• Stomach Acids kill pathogens that enter your body in food

Second Line of Defense

• White blood cells – fight pathogens that get through the first line

• Types of white blood cell s used in 2nd defense:– Phagocytes –

swallow and destroy pathogens

Third Line of Defense• Attacks specific pathogens• Involves phagocytes, T-Cells, and B-cells

(types of white blood cell)

• T-Cells: ATTACK • B-Cells: Make Antibodies–Antibodies – proteins made by the

body to kill a specific pathogen

Immunity

• Immunity – bodies ability to protects itself from disease

• Two Types– Active– Passive

Active Immunity

• Active Immunity – Develops after exposure to a pathogen– Immune system is prepared to respond when it

sees the pathogen again• Two ways:– Get the disease– Vaccine – small dose of weakened pathogen

introduced to body

Passive Immunity• Passive Immunity – Antibodies made by

one organism are transferred to another organism

• Acquired:– before birth, mother to baby–Vaccines with Antibodies• Rabies

Why might frequent hand washing help protect your from disease? What are some other ways your could protect yourself and other people from disease?

Immune System: Lesson Review

1. By which process can a person acquire active immunity to a disease?–A. Injection with antibodies–B. Treatment with antibiotics–C. Vaccination–D. Following Sanitary Procedures

Immune System: Lesson Review

2. Which substance is involved in both active immunity and passive immunity?–A. Antibiotic–B. Antibody–C. Vaccine–D. Mucus

Immune System: Lesson Review

3. How do phagocytes protect the body from disease? A. They produce white blood cellsB. They engulf and kill pathogensC. They produce T and B cellsD. They prevent pathogens from entering the body

Immune System: Lesson Review

4. Your mother is worried because she heard that the chickenpox vaccine your baby brother is going to receive is actually a weakened form of a viral disease. How do you explain to her that being injected with the disease will actually help protect your brother?

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/keepinghealthy/