Immune System- Unit 4

Pathogens

foreign particles such as viruses, bacteria, and parasites that cause an immune response

Viruses

influenza, HIV, chicken pox

Bacteria

food poisoning, syphilis, strep throat

Parasites

athletes foot, malaria, giardia

Innate Immunity

Nonspecific defenses, first line, successful in averting most infections

When is innate and adaptive immunity acquired?

Innate is present at birth and adaptive is acquired in response to previous infection

Barriers of Innate Immunity

physical and chemical barriers; specialized white blood cells

What mediates adaptive immunity?

specialized white blood cells called lymphocytes

What type of immunity has memory?

Adaptive

What are insects physical barrier against infection?

exoskeleton

Lysozyme

breaks down bacterial cell walls in digestive system to protect against pathogens ingested with food

What is the purpose of the proteins produced by the immune cells of insects?

to bind to molecules specific to a broad class of pathogens

Identity Tags

molecules for pathogen recognition 

Phagocytosis Steps 

1. Pseudopodia surround pathogens 

2. Pathogens are engulfed by endocytosis 

3. Vacuole forms

4. Vacuole and lysosome fuse

5. Pathogens destroy

6. Debris from pathogens released

What carries out phagocytosis in invertebrates?

hemocytes within the hemolymph

Phagocytosis

the ingestion and breakdown of foreign substances, including bacteria

How do hematocytes deal with large unicellular parasites?

by forming a capsule around them

How do hemocytes disrupt the plasma membranes of fungi and bacteria? 

by releasing antimicrobial peptides 

Innate defenses of vertebrates

barrier defenses, phagocytosis, and antimicrobial peptides

Defenses unique to vertebrates

natural killers cells, interferons, inflammatory response

Skin and Mucous Membranes

physical barriers; layers of tightly packed cells to prevent pathogens from entering the body

What parts of the body are lined with mucous membranes?

digestive, respiratory, urinary, and reproductive tracts

What is the purpose of mucus?

to trap pathogens and other particles

What prevents the growth of bacteria in the skin and digestive system?

the low pH

What chemical and cellular defenses tale action when a pathogen breaches a physical barrier and infection occurs?

Proteins kill invading microbes, high temp response, inflammation response, cells kill invading microbes

Complement Proteins

in the blood; can damage bacterial cells so phagocytes can destroy them

Complement System

very effective chemical defense in vertebrates; approx. 20 different proteins that circulate in plasma; inactive until they encounter a fungal or bacterial cell wall

Membrane Attack Complex

complement proteins formed together to form a pore in the foreign cells membrane causing water to rush in and burst the cell

Phagocytes

white blood cells; ingest and destroy pathogens; triggers inflammation and adaptive immune response; all the killing cells

3 types of killing cells

macrophages, neutrophils, and natural killer cells; all part of innate immune response

Lymphocytes

T-cells and B-cells; adaptive immune response