Pathogens
These are agents that cause disease, infect a wide range of animals (including humans)
Function of immune system
recognize foreign bodies and responds with the production of immune cells and proteins
Immune Cells
Get activated when there is an infection
Innate Immunity
active immediately upon infection. Present before any exposure to pathogens and is effective from the time of birth.
Adaptive Immunity
develops after exposure to agents such as microbes, toxins and other foreign substances
Where is the innate system found?
Animals and plants
First response
In vertebrates, innate immunity is a first response to infections and also serves as the foundation of adaptive immunity
Innate Immunity in invertebrates
exoskeleton made from chitin forms the barrier to pathogens
Lysozyme
enzyme that breaks down bacterial cell walls
Hemocytes
circulate within hemo-lymph and carry out phagocytes; the ingestion and digestion of foreign substances including bacteria
How does the immune system recognizes bacteria and fungi?
By the structures on their walls.
How does the immune system react to different classes of pathogens?
The Innate immune responses are different for different classes of pathogens.
What are other additional defenses unique to vertebrates?
1. natural killer cells
2. interferon
3. inflammatory response
Barrier Defenses Example
Skin doesn't allow bacteria to come inside the body
Barrier Defenses include
skin and mucous of the respiratory, urinary and reproductive tracts.
Mucous Function
trap and allow the removal of microbes
Body fluids hostile to microbes
saliva, mucus, and tears
What prevents growth of bacteria in skin and digestive system?
Low pH
Phagocytic cells
recognize groups of pathogens using toll-like receptors (TLR's)
2 types of phagocytic cells in mammals
1. Neutrophils
2. Macrophages
Neutrophils
engulf and destroy pathogens
macrophages
found throughout the body
dendritic
stimulate development of adaptive immunity
eosinophils
discharge destructive enzymes
Natural Killer Cells
detect abnormal cells and release chemicals leading to cell death
Peptides and proteins
attack pathogens or impeding their reproduction
Interferon proteins
provide innate defenses, interfering with viruses and helping active macrophages
Complement system
causes lysis of invading cells and helps trigger inflamation
Inflammatory response
brought about by molecules released upon injury of infection
histamine
triggers blood vessels to dilate and become more permeable
Cytokines
chemical signals that enhance the immune system
Septic Shock
condition caused by an overwhelming inflammatory response
Pathogens avoiding destruction
modify surfaces to prevent recognition or by resisting breakdown following phagocytosis
Adaptive Response
Receptors provide pathogen-specific recognition
T cells
mature in the thymus
B cells
mature in the bone marrow
antigens
substances that can elicit a response from a B or T cells
Epitope
small accessible part of an antigen that binds to an antigen receptor
What are B nd T cells specialized?
to recognize a specific type of molecule
Make antibodies?
B-cells