Chapter 35- Infectious Diseases

Pathogens What is an infectious disease? Five types: When a microorganism harms the body. Five types: Bacteria Fungi Parasitic Worms Viruses Protists

Scientists- Pasteur and Koch Germ theory of Disease Scientists- Pasteur and Koch Symbionts vs pathogens Symbionts- microorganisms that cause no harm, live in symbiosis with host Pathogen- microorganisms that harm the host

Disease and how they spread Coughing Sneezing Physical contact Body fluids Contaminated water/food

Animal connection Vectors- Carry pathogens but it does not harm the actual carrier. ( Ex. Mosquitos carry Zika) Zoonosis- diseases that can be transmitted from animal to human

Defenses against Infections Your body’s first line of defense! Non-specific Defense Skin, tears, secretions like phlegm, boogers, inflammatory response, interferons, fever.

Non-specific defense Inflammatory response Causes infected areas to become red and swollen. Pathogen stimulates mast cells to produced HISTAMINES. Histamines are chemicals that cause increase blood flow and fluids to affected area. Blood vessels swell and release liquid, causes swelling White blood cells called phagocytes engulf pathogen and destroy it. The area increases in temperature, infected area may feel warm.

Interferons Interferons- when viruses infect organism, certain cells produce protein that interferes with the viruses production of protein for reproduction. This slows down how quickly viruses can reproduce and allows the body to start SPECIFIC DEFENSES.

Fever Immune system releases chemical that increase body temperature. Pathogens don’t like heat or extreme cold. It slows their reproduction and also speeds up the immune system responses.

Crash Course- Non-specific Defense Crash Course Non specific Defenses

Specific defenses Specific response identifies the “self” to and “other” (pathogen), it reacts to destroy any foreign substance. It responds to SPECIFIC pathogens. Immune system recognizes self and other by chemical markers, like a password. Once it identifies an intruder; it uses chemical weapons to destroy it and it also stores chemical make up of pathogen into its memory.

IMMUNE RESPONSE The specific recognition, response, and memory. Antigens- specific immune molecules, a foreign substance that can stimulate an immune response Antigens are located on outer surfaces of pathogens

How does the body respond to antigens? It increases the number of cells that attack the invaders or produce proteins called antibodies. Antibodies- role is to tag antigens for destruction by immune cells. Where do you find antibodies? May be attached to immune cells or free floating in plasma(blood).

Antibodies Immune system makes up to 10 billion antibodies. Each bind to a specific antigen.

Lymphocytes B cells and T cells are the main type of cells that sustain the immune system. They are both types of lymphocytes; Both are made in bone marrow although T cells mature in the THYMUS while B cells mature in bone marrow. Each B and T cell can recognize any particular antigen. (passed down by genes) B cells- have embedded antibodies discover antigens in body fluids. T cells – must presented with the antigen by infected body cells or immune cells that have encountered the antigen.

Humoral immunity Depends on actions of antibodies that circulate in the blood and lymph. Antibodies on B cells bind to antigens on the surface of antigens. Pg. 1017 This causes growth and division of many B cells (PLASMA and MEMORY)

Plasma and Memory B cells Plasma cells produces and releases antibodies that are carried in blood. Flags the antigen when it binds to it, makes other parts of the immune system to attack and destroy it. Plasma cells die after infection is gone but some B cells that recognize the antigen remain. These become B Memory cells, they react quickly when same pathogen enters the body again.

Cell mediated immunity Depends on macrophages and several types of T cells. Defends against Viruses, fungi. T cells also protect from our own cancerous cells Pg. 1019 When a cell is infected by a pathogen or macrophage, the cell displays the antigen and then calls on CYTOTOXIC cells- kills the cells by puncturing their membranes with APOPTOSIS- programmed cell death