What makes us sick?… …pathogens make us sick An organism or substance that causes disease ...

What makes us sick?…

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.



QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.


……pathogens make us sickpathogens make us sick An organism or substance that causes diseaseAn organism or substance that causes disease Contains an Contains an antigen-antigen- substance that triggers substance that triggers

an immune responsean immune response ExamplesExamples

Bacteria (streptococcus)Bacteria (streptococcus) Viruses (influenza)Viruses (influenza) Fungi (ringworm)Fungi (ringworm) Worms (tapeworm)Worms (tapeworm) Protists (malaria)Protists (malaria) Toxins/venoms (exotoxin)Toxins/venoms (exotoxin)





What makes a good pathogen?What makes a good pathogen?

Multiplies rapidlyMultiplies rapidly Fools the immune systemFools the immune system Doesn’t kill its hostDoesn’t kill its host Survives for a while outside the hostSurvives for a while outside the host


VirusesViruses

• Discovered in 1898 by Friedrich Loeffler and Paul Frosch (foot in mouth disease)

• Infectious particle smaller than any bacteria (20 - 200 nanometers)

• Depend on host cell to reproduce• Not necessarily considered living



Virus structure and mechanismVirus structure and mechanism

• Protein capsule + DNA or RNA (retroviruses have RNA)

• Infected cell produces viral DNA & protein instead of its own proteins

• smallpox, cold, chickenpox, influenza, herpes, polio, rabies, Ebola, hanta,

• Generally can only infect you once

RetrovirusRetrovirus

• Best example: HIV (human immunodeficiency virus)

• Contains RNA and reverse transcriptase enzyme

• Enters cell and reverse transcribes RNA into DNA

• DNA inserts itself into host cell genome• DNA instructs cell to make HIV proteins & RNA

• Proteins self-assemble and bud out of the cell membrane

• New virus takes a piece of the membrane with it

Retroviral actionRetroviral action

BacteriaBacteria Kingdom Monera: prokaryotic cellsKingdom Monera: prokaryotic cells

Single-celled organisms found virtually Single-celled organisms found virtually everywhere everywhere (500 species in your mouth)(500 species in your mouth)

Different shapes, colors, sizes (20 nm-1 Different shapes, colors, sizes (20 nm-1 mm), cell wall components, energy, mm), cell wall components, energy, motilitymotility

Live freely in and out of hostLive freely in and out of host E. coli, streptococcus, staphylococcus, E. coli, streptococcus, staphylococcus, anthrax, plagueanthrax, plague



How do we get infected?How do we get infected? Modes of Modes of transmission:transmission: Direct contact: with Direct contact: with open sores or body open sores or body fluids (hands, mouth, fluids (hands, mouth, genitals) genitals)

Indirect contact: food, Indirect contact: food, water, doorknobs, etc. water, doorknobs, etc. can be contaminated can be contaminated with a pathogenwith a pathogen

Inhaling airborne Inhaling airborne pathogenspathogens

Disease vector (insect, Disease vector (insect, tick, etc.) Do you know tick, etc.) Do you know any examples?any examples?

QuickTime™ and a decompressor






What makes us sick?… …pathogens make us sick An organism or substance that causes disease ...

Documents

Transcript of What makes us sick?… …pathogens make us sick An organism or substance that causes disease ...