Let’s get DEFENSIVE

Triggering a response Antigen: Any substance capable of triggering an immune response. Can be a bacterium or a virus. Can be tissues or cells from another individual Pathogen: Any disease causing agent

Lymphatic system A network of glands and vessels that drain interstitial fluid from body tissues and return it to the circulatory system. interstitial fluid circulatory system Fluid is “scanned” for foreign cells

Lymph organs bone marrow lymph nodes spleen thymus

Function of 2 Main Groups of Cells 1. Leukocytes—Non-specific defense. Rely on Phagocytosis to ingest invading microbes. They include Macrophages and White Blood Cells. 2. Lymphocytes—Provide high specificity and diversity to the immune system. Allow for extremely aggressive response to a microbial attack. They include B-Cells and T-Cells

Problem Foreign cells like bacteria enter the body and consume our cells and damage tissue. Foreign cells give off toxins, chemical by products of their metabolism, that are poisonous to many of our cells (enzymes) How to identify and destroy only the foreign cells and not attack our own?

Three Level Approach to Problem Level I - Non-Specific Defense: Prevent entry Skin Mucous Membrane Secretions of skin and mucous membranes

Level 2 – Non-Specific Defense: Search/Destroy at point of attack foreign objects White blood cells Antimicrobial proteins Inflammatory response

 Damaged cells release chem. Signals:  histamines  protoglandins  Capillaries dilate  More permeability  Clotting elements (Platelets) appear  Clotting begin  Phagocytic leukocytes enter region  Attracted to chem. sig.  Leukocytes consume pathogens and cell debris by phagocytosis

Level 3 - Specific Defense: Complex system of interacting cells (immune pathway) Pathogen  Macrophage  T- Cell  B-Cell  Antibodies

Macrophages identify germs When a germ invades our bodies, macrophages gobble up the germ and display its surface shape, or antigen, for other immune cells to see.

Helper T cells direct the defense Helper T cells spot the foreign antigen on the macrophage and begin to multiply. They alert other white blood cells and direct the body's defense.

B cells make antibodies B cells start to make chemicals called antibodies. Antibodies lock onto foreign antigens making it easier for other immune cells to destroy them.

Killer T cells destroy germs Alerted by helper T cells, killer T cells multiply and destroy the invading germs. Working together, our white blood cells can usually destroy invading germs.

Antibody An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target.

Vaccines Inactivated bacteria or virus Provokes immune response but not the disease or illness Memory cells react faster to second exposure Some pathogens mutate too quickly to be eliminated by vaccines

Viruses a. Basic Structure: Contains genetic information. Surrounded by a protein coat. They may have external structures and a membrane. NOT Living

b. Virus Diagram

c. Examples of Viruses Hepatitis B HIV Measles Mumps Rabies Ebola Influenza Do not draw

Retroviruses (backwards) Instead of DNA, Retroviruses infect cells with RNA. –The RNA is then copied into DNA by an enzyme called Reverse Transcriptase inserted as a prophage like the Lysogenic cycle. –HIV is one example of a retrovirus Can mutate very easily and become resistant to treatment – the problem w/ HIV

Viruses are not always bad! Today, in genetic research viruses are commonly used. –T–The viral genetic info can be removed and replaced with new genetic information. –T–These modified viruses can then be inserted into other organisms, allowing the virus to inject its new (good) genetic info into the host cell. Called a Vector

Bacteria (prokaryote) a. Basic Structure Lacks membrane bound organelles Except they do have small ribosomes! DNA is typically circular, not in chromosome form b. Diagram

Identifying Bacteria  Gram Staining – stain affects bacteria differently based on their cell wall structure  Gram positive = purple  Gram Negative = pink  Shape – 3 different shapes are common  Cocci -  Bacilli -  Spirilla - Sphere shape Rod shape Spiral shape

Viruses vs. Bacteria Antibiotics work on bacteria NOT on viruses