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