unit 5.1 review pbs. how are infectious diseases spread through a population? bacteria and viruses:...
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Unit 5.1 Review PBS
How are infectious diseases spread through a population?
• Bacteria and Viruses:– Most common infectious agents– Bacteria are prokaryotic organisms that can
survive on their own– Virus are not cellular and need a host to
reproduce– Spread from contact with a contaminated
person or thing and through the air• Fungus:
– Grow in warm/damp areas and can spread through spores in the air, skin to skin contact, or sharing unwashed clothes
• Protozoa:– Spread by eating contaminated food or by
vectors, like mosquitoes and malaria• Helminthes:
– Parasitic worms that are transmitted through under cooked meats and eating fecal matter
• Prions:– Mutated proteins that can happen randomly or
by infected human tissue
What is aseptic technique?• These are techniques used to
maintain a sterile environment when working with bacteria.
• Important to reduce spread of bacteria and contamination
• Aseptic techniques include– Wearing goggles, gloves, and aprons/lab
coats– Using Bleach solution to clear your area
before and after use– Keep the petri dish closed as much as
possible– Use a flame to sterilize slides and loops
before use– Wash hands and forearms
How can an unknown sample of bacteria be identified?
• Colony Morphology– Grow bacteria on Petri Dishes in
isolated colonies– Analyze the specific characteristics
of colony growth to help determine bacteria species
• Gram Staining– Stain bacteria first with grams
stain and then safranin.– Gram + will stain purple and
Gram – will stain pink• Chemical Tests– A variety of chemical tests can be
used to help identify bacteria since each species reacts differently to certain tests.
How can an unknown sample of bacteria be identified?
• Gram Staining Continued– Gram + have thick peptidoglycan wall
that absorbs purple stain– Gram – have thin peptidoglycan wall with
an outer lipid membrane. The lipid membrane washes off and then the cell wall is stained pink
• Bacteria shape– Gram staining allows us to see the shape
on the individual bacteria– Coccus – Circle– Bacilli – Rods– Spirilla - Spiral
How does the immune system function to protect the human body from foreign invaders?
Nonspecific Defense• Defense mechanisms
against all types of foreign invaders
• They do not remember or focus on a specific type of invader
• First Line– Skin – protective layer
against foreign objects– Mucus – Lines lungs and
other inner surfaces that traps and helps expel foreign objects
– Nose Hair – Filters air and traps foreign particles
How does the immune system function to protect the human body from foreign invaders?
Nonspecific Defense• Second Line
– Inflammation – Blood rushes to the area bringing phagocytes and other white blood cells to the area. Also helps to retain the infection in one area
– Phagocytes – have receptors that seek out pathogens (bad foreign invaders) and once bound to it the phagocyte eats the pathogen.
– Phagocytes can also lead into specific defense by presenting the antigen
How does the immune system function to protect the human body from foreign invaders?
Specific Defense• Defense against
specific invaders through the use of antigens and antibodies
• This comes into play after the invader gets past the nonspecific defense
• Two main cells are T-cells and B-cells
How does the immune system function to protect the human body from foreign invaders?
Specific Defense• Antigens are
proteins on the pathogens that tells human cells what they are.
• The phagocyte presents the antigen to helper T-cells that will produce proteins to activate B-cells
How does the immune system function to protect
the human body from foreign invaders?
Specific Defense• B-cells are activated by T-cells and also
connects to pathogen antigens• B-cells produce plasma cells that make
antibodies specific to the antigen.• The antibodies attach to the antigen and
mark it for phagocytes to destroy.• B-cells also produce memory cells that
will “remember” same antigen so if the pathogen invades again the immune response will be faster