1. “Fighting the Enemy Within”
Topic: Immune System
Aim: How does our immune system protect us against pathogens?
“Fighting the Enemy Within”
phagocytic leukocyte
lymphocytes
attacking
cancer cell
lymph
system

2. What are pathogens? Anything that causes sickness or diseases.
Examples:
Fungi
Bacteria
Parasites
Viruses

3. Points of entry How can pathogens enter our body? digestive system
respiratory system
urinary system
genitals
break in skin

4. Why do we need an immune system?
Attack from the outside & inside
lots of organisms want you for lunch!
we are a tasty vitamin-packed meal
cells are packages of proteins, carbohydrates & fats
no cell wall
animals must defend themselves against invaders
viruses
HIV, flu, cold, measles, chicken pox, SARS
bacteria
pneumonia, meningitis, tuberculosis
fungi
yeast
protists
amoeba, Lyme disease, malaria
cancer cells
abnormal body cells
What’s for lunch?!

5. How does the immune system recognize invaders/pathogens?
Antigens
chemical name tags on the surface of every cell
“self” vs. “invader”
one of your own cells
disease-causing virus
disease-causing bacteria
antigens say: “I belong here”
antigens say: “I am an invader”
antigens say: “I am an invader”

6. Your Body has 3 Lines of Defense to Protect You
1st line: Physical Barriers
broad, external defense
“walls & moats”
skin & mucus membranes
2nd line: Non-specific
broad, internal defense
“patrolling soldiers”
phagocyte (eating) white-blood cells
(WBCs)
3rd line: Specific-response (Immune System
specific, acquired immunity
“elite trained units”
lymphocyte WBCs & antibodies
B & T cells

7. 1st line: Physical Barriers
non-specific defense
external barriers
skin & mucus membranes
excretions
sweat
stomach acid
tears
mucus
saliva
“lick your wounds”
Lining of trachea: ciliated cells & mucus secreting cells

8. 2nd: Generalist, broad range patrols
Patrolling white blood cells
attack invaders that get through the skin
recognize invader by reading antigen
surface name tag
phagocyte cells
macrophages
“big eaters”
Macrophage “eating” bacteria

9. 2nd “circulatory” system
Production of white blood cells & traps “foreign” invaders
Lymph system
lymph vessels
(intertwined amongst blood vessels)
2nd “circulatory” system
lymph node

10. white blood cells that eat
Phagocytes
macrophage
bacteria
white blood cells that eat
macrophage
yeast

11. Why do injuries swell? Inflammation
injured cells release chemical signals
histamines
increases blood flow
brings more white blood cells to fight bacteria
brings more red blood cells & clotting factors to repair
Blood clot
Pin or splinter
Swelling
Bacteria
Chemical
alarm signals
Phagocytes
Blood vessel

12. Fever When a local response is not enough
full body response to infection
raises body temperature
higher temperature helps in defense
slows growth of germs
helps macrophages
speeds up repair of tissues
Certain bacterial infections can induce an overwhelming systemic inflammatory response leading to a condition known as septic shock.
Characterized by high fever and low blood pressure, septic shock is the most common cause of death in U.S. critical care units.
Clearly, while local inflammation is an essential step toward healing, widespread inflammation can be devastating.

13. 3rd line: Lymphocytes(Antibody)
B cell
Specific defense
responds to specific invaders
recognizes specific foreign antigens
white blood cells
B cells & antibodies
T cells

14. B cells & antibodies B cells Patrolling B cells Memory B cells
white blood cells that attack invaders in blood
mature in Bone marrow
Patrolling B cells
make antibodies against invader immediately
Memory B cells
remembers invader
can make antibodies quickly the next time
protects you from getting disease more than once

15. Antibodies
Proteins made by B cells that tag invaders in the blood so macrophages can eat them
tag says “this is an invader”  gotcha!
biological “handcuffs”
antibody attaches to antigen of invader Y
invading germs tagged with antibodies
B cells releasing antibodies Y Y
macrophage eating tagged invaders

16. B cells immune responseY
B cells immune response Y
B cells
release antibodies
patrol blood
forever
invader (foreign antigen) Y Y
“reserves”
memory B cells Y
B cells
recognition Y Y
10 to 17 days

17. Vaccinations Exposure to harmless version of germ
stimulates immune system to produce antibodies to invader
rapid response if future exposure
Most successful against viral diseases

18. Jonas Salk 1914 – 1995 Developed first vaccine against polio
Poliomyelitis (polio) is caused by a virus that enters the body through the mouth. The virus multiplies in the intestine and invades the nervous system. It can cause total paralysis in a matter of hours.
One in 200 infections leads to irreversible paralysis. Among those paralyzed, 5-10 percent die when their breathing muscles are immobilized.
Polio mainly affects children under age 5.
April 12, 1955

19. Polio epidemics 1994: Americas polio free
1916 The first major polio epidemic strikes in the United States; 27,000 people suffer paralysis and 6,000 die. Increasing numbers of outbreaks occur each year.
1921 Franklin D. Roosevelt is diagnosed with polio.
1928 Iron lungs are introduced to help patients with acute polio breathe.
1932 Franklin D. Roosevelt is elected President of the United States
1949 Dr. John Enders, Dr. Frederick Robbins and Dr. Thomas Weller develop a way to grow poliovirus in tissue culture, a breakthrough that aided in the creation of the polio vaccine. Their work earned the three scientists the Nobel Prize in physiology and medicine in 1954.
1952 The United States reports 57,628 polio cases -- the worst U.S. epidemic on record.
1979 The last U.S. case of polio caused by wild poliovirus is reported.
1988 Worldwide, polio continues to affect some 350,000 people in 125 countries.
1994 The Americas are certified polio-free.
2000 The Western Pacific region is certified polio-free.
2002 Europe is certified polio-free.

20. Protecting you from disease
Vaccinations
advantage
don’t get illness
long term immunity
produce antibodies for life
works against many viruses & bacteria
disadvantage
not possible against all invaders
Breastfeeding
mother’s milk gives baby antibodies & keeps baby healthy`
IMPORTANT PROTECTION
antibodies pass from mother to baby in breast milk

21. You need trained assassins to kill off these infected cells!
What if the attacker gets past the B cells in the blood & infects some of your cells?
You need trained assassins to kill off these infected cells! T
Attack of the Killer T cells!

22. T cells T cells mature in Thymus Helper T cells Killer T cells
sound the alarm for rest of immune system
Killer T cells
destroy infected body cells
Memory T cells
remembers invader & reacts against it again quickly
Where’s that?

23. Thymus

24. Attack of the Killer T cells
Killer T cells destroy infected body cells
T cell binds to invaded cell
secretes perforating protein
punctures cell membrane of infected cell
cell bursts
Killer T cell
vesicle
Perforin punctures cell membrane
cell membrane
cell membrane
invaded cell

25. Immune response Y Y invader skin skin invaders in body
invaders in blood
invaders infect cells
macrophages
B cells
helper T cells
T cells
patrolling B cells
memory B cells
memory T cells
killer T cells Y
antibodies Y
antibodies

26. Diseases of the immune system
HIV: Human Immunodeficiency Virus
infects helper T cells
helper T cells can’t activate rest of immune system
body doesn’t hear the alarm
AIDS: Acquired ImmunoDeficiency Syndrome
immune system is weakened
infections by other diseases
death from other invading diseases or cancer

27. How to protect yourself…

28. Curing you of disease Antibiotics = medicine advantage disadvantage
kill bacteria that have successfully invaded you
make you well after being sick
disadvantage
use only after sick
only good against bacteria
possible development of resistance by bacteria (if don’t use correctly)
can get sick again

29. Immune system malfunctions
Auto-immune diseases
immune system attacks own cells
lupus
antibodies attack many different body cells
rheumatoid arthritis
antibodies causing damage to cartilage & bone
diabetes
insulin-making cells of pancreas attacked & destroyed
multiple sclerosis
T cells attack myelin sheath of brain & spinal cord nerves
fatal

30. Immune system malfunctions
Allergies
over-reaction to harmless compounds
allergens
proteins on pollen
proteins from dust mites
proteins in animal saliva
body mistakenly thinks they are attackers

31. What are pathogens?________________________________
Review Questions
Which body system is primarily responsible for protecting you against pathogens?________________________________
What are pathogens?________________________________
____________________________________________________
3. How can pathogens enter your body? ____________________
4. How many lines of defense does your body have to protect itself against pathogens? _____________________

32. 5. How are the 2nd and the 3rd line of defense different? ________
Review Questions
5. How are the 2nd and the 3rd line of defense different? ________
____________________________________________________________________________________________________________________________________________________________
6. Which line of defense is considered “specially trained” to take out specific target? ________________________________
7. How do antibodies recognize pathogens? _________________

33. 8. What is autoimmune disease? __________________________
Review Questions
8. What is autoimmune disease? __________________________
________________________________________________________________________________________________________________________________________________________________________________________________________________
9. Choose 1 autoimmune disease and briefly describe how it affects the victim? _____________________________________
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

34. destruction of infectious agents by white blood cells
1. Which phrase does not describe a way the human body responds to fight disease?
destruction of infectious agents by white blood cells
production of antibodies by white blood cells
increased production of white blood cells
production of pathogens by white blood cells
2. The diagram below represents one type of white blood cell. This type of white blood cell ingests microbes.
A function of another type of white blood cell is to
prevent the loss of blood from a wound
produce specialized molecules that mark invaders
increase the number of red blood cells in the blood
cause gene mutations that will increase immune responses

35. 4. Microbes that enter the body, causing disease, are known as
3. The diagram below represents one possible immune response that can occur in the human body.
The structures that are part of the immune system are represented by
A, only
A and C, only
B and C, only
A, B, and C
4. Microbes that enter the body, causing disease, are known as
pathogens
antibodies
enzymes
hosts