Fighting Disease The Immune Response

Introduction Many bacteria are pathogenic – they cause diseases as a result of tissue destruction Once pathogens enter the body they begin to produce toxins that travel through the circulatory system – they cause fever, chills, etc.

Immune system continued… The site of entry is not necessarily the location where symptoms will occur: stepping on a rusty nail contaminated with Clostridium tetani leads to tetanus tetanus is often called ‘lockjaw’ because the bacteria produce a neurotoxin that causes spasms and locking of the muscles if this spreads to the muscles in your ribs you can asphyxiate (suffocate)

The Immune System has three levels of defence: 1. External unbroken skin is nearly impenetrable to bacteria  some may enter through sweat glands or hair follicles, but these contain salts and amino acids that are toxic to bacteria

other bacteria enter through respiratory passages  specialized cells secrete mucus which is sticky and traps bacteria you inhale  mucus also contains digestive enzymes that destroy bacterial cell walls  passages also contain cells with cilia which sweep trapped bacteria up the throat (where they are swallowed, or expelled)

bacteria that enter the eyes are attacked by digestive enzymes in tears  tears drain into the upper sinuses where any remaining bacteria are destroyed by the enzymes in mucus bacteria that are ingested in food and drink ate attacked by acids in the stomach

2) The Lymphatic System a complex network of organs connected by a specific circulatory system of vessels and nodes lymph is circulated through the vessels a transparent fluid containing white blood cells (WBC) called lymphocytes (produced by lymph nodes)

as lymph flows through lymph nodes and the spleen, microorganisms are filtered out (before the can enter the bloodstream) after it is filtered, lymph is moved into the bloodstream where lymphocytes act as guards

bone marrow produces specialized WBC called macrophages  mobile cells that travel across body membranes to find, engulf and kill foreign invaders (phagocytosis)  in the process the microphage usually dies, and dead macrophages + dead bacteria form pus. bacterium macrophage

3) ANTIBODY FORMATION YES, You Must Draw and label this Diagram!

Types of Immunity Active Immunity The body itself produces the antibodies to kill invading bacteria Can be acquired naturally Person is infected, produces antibodies and recovers (i.e. chicken pox infection in a child)

Active Immunity continued… Can be artificially produced Vaccinations that contain dead or weakened bacteria (i.e. flu shot) Body reacts by producing antibodies Can be lifelong (diphtheria) or need to be renewed (flu)

2) Passive Immunity The antibodies are injected into the bloodstream Antibodies passed from mother to child during late pregnancy/early breastfeeding Antibodies produced by another animal are injected into recipient (i.e. tetanus shots are horse antibodies)

Resisting Infection Infectious disease can be spread through moisture droplets in the air, direct contact, fecal contamination, animal bites, wounds, etc. To protect yourself you can: Sterilize equipment (i.e. tattoo needles) Use disinfectants (i.e. chemical sanitizers) Use antiseptics (i.e. antibacterial soap) Exterminate disease carrying animals (i.e. avian flu, BSE) Antibacterial medication (i.e. polysporin)