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