1. The Immune System

2. What is the Immune System?
What is a pathogen?
Disease-causing organisms that can be
present in air, water, food
Pathogens are viruses, bacteria, fungi,
protists, and parasites
What is a disease?
Any condition that prevents the body from working as it should
What causes a disease?
Pathogens, cancer, toxic substances, poor nutrition, organ malfunction, inherited disorders, or risky personal behavior
What is an infection?
Person has symptoms and medical signs of being infected by pathogen
What is the Immune System?
The body’s primary defense against
disease-causing pathogens that enter body
Immune system makes WHITE BLOOD
CELLS and ANTIBODIES to destroy pathogens

3. Fighting Infectious Diseases:
Nonspecific defenses: First line of Defense-
Do not discriminate between one threat and another.
Examples
THE SKIN – the body’s most important line of defense
Mucus, saliva, tears- contain enzymes to break down the cell walls of many bacteria
Stomach acid – destroy pathogens that make it as far as your stomach

6. Specific Defenses Attack particular disease causing agents
Kill foregin substances that enter body (shape-specific antibody production response)
The reaction of the body to particular pathogens

7. Antibodies Proteins made by WBCs that recognize and bind to antigens.
Carried through the bloodstream to attack the pathogen causing the infection.
Antibodies attack invaders or mark them for destruction by other white blood cells- killer cells

8. Killer cells

10. Antigens
Molecule found on the cell membrane of a pathogen or cancer cell
Antigens cause immune system to react to presence of pathogens, toxins, cancer cells

11. What is passive immunity?
Antibodies passed from mother to child through breast milk
What is active immunity?
Developed when exposed to antigen from fighting infection (example- chicken pox) or from antigen in vaccines (shots)
White blood cells produced after exposure- (memory cells)
What is a Toxin?
Toxins are the poisonous wastes of certain
pathogens like bacteria
Toxins act as antigens

12. Active immunity

13. Disease can cause a Failure in Homeostasis
What is Diabetes?
Disease where your body is unable to produce insulin (hormone that lowers blood sugar)
As a result, one is unable to control blood glucose levels
What causes Diabetes?
Type 1 Diabetes: birth defect- Missing gene
Type 2 Diabetes: (Lifestyle) over-eating carbohydrates, poor diet and exercise
Can Diabetes be cured?
There is no known cure for diabetes
Current research in gene therapy/splicing
What is the treatment for Diabetes?
Strict diet and glucose monitoring

15. What happens to a person with cancer?
What is HIV?
Human Immunodeficiency Virus destroys helper T cells ( type of white blood cell)
What is AIDS?
Acquired Immune Deficiency Syndrome
occurs when immune system is weak an unable to fight off infections
The majority of helper T-cells are destroyed
What is cancer?
Uncontrolled cell division and growth
What happens to a person with cancer?
The body might kill cancer cells if detected
Life may be threatened if immune system
can’t kill cancer cells
Surgery, radiation, chemotherapy

17. What are White Blood Cells (Leucocytes)?
Cells made by immune system to destroy pathogens, toxins, cancer cells
Cells can tell difference between body
cells and foreign invaders (pathogens)
What are phagocytes?
White blood cell that engulfs and digests
pathogens

20. What are vaccines? What is a microbe? How do vaccines work?
Consists of a weakened, killed or parts of a pathogen
Injected into the body to stimulate immune system to produce antibodies that will kill microbes that enter body in future
What is a microbe?
Microscopic organism such as bacteria
How do vaccines work?
After entering body, antibodies are produced for that specific pathogen.
After vaccination, immune system remembers pathogens by producing memory white blood cells that protect body for years.
Memory white blood cells react quickly when invasion of same pathogen occurs.

22. What can damage the immune system?
Immune system weakens with age
Stress and fatigue
Some viruses attack immune system and
cause disease.
What kinds of problems can occur with the
immune system?
Allergies, leukemia, AIDS
What is an ALLERGY?
A reaction to some substance (allergen) in environment that causes runny nose, sneezing, rash, or swelling
What causes an allergic reaction?
Allergens that are normally harmless
What are some substances that can cause an allergic reaction?
Certain foods, pollen, and chemicals from insect bites (bees/wasps)
What is the response of the immune system in an allergic reaction?
Immune system releases histamines that cause swelling, runny nose and rash

24. How can allergic reactions be treated?
People can take antihistamines (drug)
How does the immune system react to an organ transplant? What is tissue rejection?
Immune system attacks transplant
Transplant patient take drugs that suppress the immune system
Tissue rejection is when transplanted organ is rejected in body
White blood cells attack new organ
What is antibiotic resistance?
ANTIBIOTICS: drug that will kill
pathogens like bacteria (not viruses)
Pathogens are able to survive when exposed to antibiotics

26. What are infectious or communicative diseases?
What is asthma?
Disease where air passages
narrow or thin
This causes difficulty breathing
Triggered by respiratory infections,
exercise, stress, pollutants, mold, smoke, and pollen
What is Leukemia?
Cancer of the bone marrow or blood
What are infectious or communicative diseases?
Disease where pathogen can be spread through objects, sneezing, touching, food, water, insects and air

28. Examples of infectious disease: What are non infectious diseases?
Bacteria, virus, protists
What are non infectious diseases?
Disease not caused by a pathogen
Can not be passed to others (contagious)
Examples of noninfectious diseases:
Cancer, asthma, heart disease

29. Immune system Video KidsHealth.org

30. Sample Regents Questions
1. Many bacteria that enter the circulatory system are engulfed and destroyed by  A.  phagocytic white blood cells B.  pinocytic red blood cells C.  plasma D.  platelets

31. 2. Which molecule of the immune system attaches to bacteria, making them easier to eat by white blood cells?
A. hemoglobin
B. antibody
C. antigen
D. Pathogen

32. A. Enzymes B. Hormones C. Sugar D. Antibodies
When a person is suffering from an infection, such as strep throat or chicken pox, his blood usually shows a significant increase in the number of
A. Enzymes
B. Hormones
C. Sugar
D. Antibodies

33. The Body is protected against harmful flu viruses by
A. red blood cells and hormones
B. white blood cells and antibodies
C. white blood cells and enzymes
D. red blood cells and antibodies

34. A vaccine can protect you against a disease because it
A. destroys toxic substances from bacteria before they make you sick.
B. stimulates your immune system against the pathogen.
C. kills any pathogenic bacteria in your body
D. changes pathogenic bacteria into harmless bacteria