Adv Biology 1-2

The Immune System The immune system protects against pathogens. Pathogen-any disease causing agent.

Nonspecific Immunity Nonspecific immunity deals with all pathogens the same. Includes parts of other systems. Epidermis (outer layer of skin) prevents entry and is constantly replaced. Mucus in the lungs traps pathogens. Acids in the stomach, vagina and bladder damage pathogens.

Nonspecific Immunity cont’d Macrophages and white blood cells “eat” pathogens. Swallow and digest them with enzymes.

Nonspecific Immunity cont’d Damaged cells release histamine. Causes blood vessels to widen. Area is flooded with fluid, white blood cells and macrophages. Pathogens and damaged cells are eaten.

Nonspecific Immunity cont’d A fever is an attempt to kill a pathogen by breaking down its proteins. The hypothalamus in the brain (regulates temperature) increases body temperature.

Specific Immunity Specific immunity responds to pathogens individually. Some is provided at birth (passive immunity). The rest come from exposure (active immunity).

Specific Immunity cont’d White blood cells are made in bone marrow. B cells mature in the bone marrow. T cells mature in the thymus (in the chest).

Specific Immunity cont’d Pathogens contain antigens. Antigen-anything that initiates an immune response. Part of the cell wall or something they produce.

Specific Immunity cont’d There are many types of B cells (but only a few of each). Antigens bind to a specific B cell or T cell. The body then mass produces the necessary B or T cell.

Specific Immunity cont’d B cells produce antibodies (a protein that binds to a specific antigen). Macrophages then eat the pathogen. Some B cells become memory cells. Remember what antibody to make later. Later infections are dealt with faster.

Specific Immunity cont’d T cells attack viruses and fungi. Macrophages swallow a pathogen and presents its antigens to a helper T cell. Helper T cells stick to the antigen, activating killer T cells. Killer T cells stick to the pathogen and cut it up.

Antibiotics Antibiotics are chemicals for curing bacterial infections. Most attack peptidoglycan in the cell wall. Cause the cell wall to fall apart and the bacteria to explode. Others interfere with transcription or translation.

Vaccines A vaccine is a harmless or dead virus given to help the body develop a response. The body responds without getting really sick (or dying) and memory cells are produced. Later infections are dealt with faster and with fewer symptoms.