the immune system nonspecific and specific defense you do not need to write down anything in blue
TRANSCRIPT
What is a pathogen?• Pathogen:Pathogen: disease causing agentdisease causing agent
• Harmful to living thingsHarmful to living things
Check out this slow motion sneeze!
http://www.youtube.com/watch?v=e2QAGVMlns4
Examples of Pathogens include
• BacteriaBacteria
• VirusesViruses
• Parasites, Parasites, like fungi, like fungi, protists, & wormsprotists, & worms
• SoilSoil• WaterWater• Infected animalsInfected animals
• FoodFood• Animal BitesAnimal Bites
– This includes mosquitoes (West Nile Virus), ticks This includes mosquitoes (West Nile Virus), ticks (Lyme Disease), fleas (Bubonic plague), flies (Lyme Disease), fleas (Bubonic plague), flies (various infections)(various infections)
• Person-to-person contactPerson-to-person contact
How are Pathogens How are Pathogens Spread?Spread?
Q: How do bacteria cause damage to host cells?
A: By releasing poisonous substances called toxins.
• Did you know?…the Tetanus bacteria is found in soil and one drop of the toxin, the size of a period, can kill 30 people.
These images are of two men undergoing an extreme muscle
spasm caused by toxins produced by tetanus bacteria.
The Immune SystemThe Immune System
Immune System:Immune System: body system body system that fights off invading pathogensthat fights off invading pathogens
Two types of defense:Two types of defense:• Nonspecific DefenseNonspecific Defense• Specific DefenseSpecific Defense
11stst line of line of Non-Specific Non-Specific
DefenseDefense Skin: A physical barrier to A physical barrier to
pathogens.pathogens.• Any break in the skin allows Any break in the skin allows
entry.entry.• Releases sweat, oils, and Releases sweat, oils, and
waxes that contain waxes that contain chemicals toxic to bacteriachemicals toxic to bacteria..
Mucous membranes: Tissues that line internal body Tissues that line internal body surfaces that are in contact surfaces that are in contact with the environment.with the environment.• Mucous: Sticky fluid that Sticky fluid that
traps pathogens.traps pathogens.
1st line of Defense:Types of Non-specific
Defense Stomach: Has acid that Has acid that
destroys potential pathogens destroys potential pathogens that are swallowedthat are swallowed
Phagocytes: WBC’s that WBC’s that ingest (eat) pathogensingest (eat) pathogens• Macrophages: Ingest and Ingest and
destroy pathogens.destroy pathogens.• Neutrophils: Ingest Ingest
pathogens, then secrete pathogens, then secrete deadly toxic chemicals to deadly toxic chemicals to kill themkill them
• Short video clip on phagocytes: Short video clip on phagocytes: http://www.youtube.com/watch?v=CEOV-SFTlpY. .
Phagocytes and their relatives
11stst line of Defense: line of Defense:Types of Non-specific Types of Non-specific
DefenseDefense Moderate Fevers (< 103O F):
Inhibit growth of pathogens and recruit macrophages
Inflammation: Reaction to tissue damage. Phagocytes consume foreign substances. (Symptoms: swollen, redness, heat, pain)
InflammationFigure 24.2
Tissue injury; release of chemical signals such ashistamine.
1 2 3Dilation and increased leakiness of local blood vessels; migration of phagocytes to the area.
Phagocytes (macrophages andneutrophils) consume bacteria and cell debris; tissue heals.
PinSkin surface
Bacteria
Chemicalsignals
WBC
Swelling
Phagocytes andfluid moveinto area
Phagocytes
Specific Defense: The Immune System
Organs of the Immune System:• Bone Marrow:
makes WBC• Thymus gland:
where T cells mature• Lymph nodes:
contain lots of WBC• Spleen: removes
pathogens from blood
The Immune System involves many The Immune System involves many types of White Blood Cells types of White Blood Cells (aka (aka
Leukocytes / WBCs).Leukocytes / WBCs).
Here are a few types:Here are a few types:B lymphocytes: Secrete antibodies.
Antibodies: Y-shaped molecules that grab and block certain
pathogens.
T lymphocytes: Help stimulate an immune response.
You can call them B cells
and T cells for short!
Specific Defense: Recognizing Specific Defense: Recognizing PathogensPathogens
Immune Response:: your wbcs attack somethingyour wbcs attack something Antigen: anything that causes a responseanything that causes a response
Recognition: Recognition: – Lymphocytes have receptor proteins all over them.Lymphocytes have receptor proteins all over them.– Receptor proteins recognize and bind to antigens Receptor proteins recognize and bind to antigens
that match the receptor.that match the receptor.
Immune Response gets stronger over time
Primary Immune Response: 1st time a certain pathogen is encountered by the body• After infection is fought, some B and T
cells stay alive for years as memory cells.• Memory cells can divide to fight
pathogens that they “remember” if they ever meet again.