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31.1 Pathogens and Human Illness
Describe this picture.
31.1 Pathogens and Human Illness
Sponge #1
1. What do you think the white blood cell is doing
in this picture?
2. Why do you not get sick EVERYTIME disease
causing germs invade your body?
White blood cell
E. Coli (bacteria)
31.1 Pathogens and Human Illness
Sponge #1
1. What do you think the white blood cell is doing
in this picture?
The white blood cell is attacking the invader
2. Why do you not get sick EVERYTIME disease
causing germs invade your body?
The white blood cells attack and destroy
invaders before you get ill. They protect you.
White blood cell
E. Coli
31.1 Pathogens and Human Illness
KEY CONCEPT
Germs cause many diseases in humans.
31.1 Pathogens and Human Illness
• Diseases caused by germs, such as the E. Coli bacteria
can be fatal (death)
• 1330-1352, the bacteria that caused the “Black Death” or
the Plague originated from fleas on rats
– Has killed approx.
100 MILLION
people
– New diseases
-
HIV
SARS
Avian Flu (bird flu)
Swine Flu
31.1 Pathogens and Human Illness
• Germ theory proposes that microorganisms cause
diseases.
– led to rapid advances in understanding disease
– Can be infectious (polio, flu), caused by germs
– or noninfectious (cancer, heart disease) caused by
genes or lifestyle
31.1 Pathogens and Human Illness
• Disease-causing agents are called pathogens.
• What would happen if pathogens were eliminated?
– We wouldn’t get sick
31.1 Pathogens and Human Illness
There are different types of pathogens.
• Bacteria are single-celled
organisms.
– cause illness by
destroying cells
– release toxic chemicals
–
–
–
–
Exs:
E. Coli
Salmonella
“Food Poisoning”
31.1 Pathogens and Human Illness
• Viruses are disease-causing strands of DNA
or RNA that are surrounded by a protein coat.
– Take over a healthy cell
– Force cells to produce more of the virus
– Smaller than bacteria
– Exs:
– HIV
–
–
–
–
Influenza
Herpes
*Common Cold
AIDS
31.1 Pathogens and Human Illness
• Fungi can be multicellular or single-celled.
– take nutrients from host’s cells
– occur in warm and damp places
Ex: Athlete’s foot, yeast, mold
31.1 Pathogens and Human Illness
• Protozoa are single-celled organisms
– Prey on other cells
– use host cells to complete their life cycles
– take nutrients from host cell
– Ex: Malaria, dysentery
31.1 Pathogens and Human Illness
• Parasites are multicellular organisms.
– grow and feed on a host
– possibly kill the host
Ex: Heart worm
Round worm
Elephantiasis- mosquitos
31.1 Pathogens and Human Illness
• Vectors any person or animal that carries and transmits a
pathogen to another living organism.
• Direct contact requires touching an infected individual.
Includes:
– kissing
– sexual intercourse
– hand shaking
– bite
tick
Ex:
Lime Disease- ticks
Malaria- mosquito
West Nile Virus- mosquito
Rabies- rabid animal
HIV- infected person
31.1 Pathogens and Human Illness
Pathogens can enter the body in different ways.
• Direct contact require an infected person or animal to
physically touch a healthy person Ex: Rabies, HIV
• Indirect contact does not require touching an infected
individual.
– touching an infected
surface
– breathing in infected
air Ex: SARS
Tuberculosis
31.1 Pathogens and Human Illness
• Different pathogens cause common infectious diseases.
31.1 Pathogens and Human Illness
Bacteria Videos
Beneficial Bacteria
• Types
• Functions
• Examples
Harmful Bacteria
• Types
• Functions
• Examples
Take notes on the
two videos
31.1 Pathogens and Human Illness
Beneficial Bacteria
• Decomposers
– Break down dead material
• Soil
– Makes it fertile so plants can
grow
• Intestines
– Aids in digestion
– Produces vitamins
• Food
– Cheese, sour cream, yogurt
• Medicine– help fight diseases
• Sewage Treatment
• Oil spills
Harmful Bacteria
• Take over ponds, etc.
– Kills existing life
• Food
– Grows on food (spoils)
• Mouth
– Feed on food in between
teeth
- Must brush and floss
• Infect
– Open sores
• Difficult to kill
– May have a slippery outer
capsule
31.2 Immune System
Homework
Draw a double-bubble map
comparing and contrasting bacteria
and viruses (pg. 942 & notes)
31.2 Immune System
Smaller than Bacteria
Single- celled
Have a protein
coat
Pathogens
HIV
E. Coli
Bacteria
Release toxic
chemicals
microscopic
Infectious
Viruses
Flu
Force cells to
produce more
virus
Common cold
Larger than
viruses