The First and Second Lines of Defense Against Disease BY JEFF HOFFMAN

What are the immune systems’ 1 st & 2 nd lines of Defense? -The first 2 lines of response of the immune system are called INNATE IMMUNITY. -During the early stages of an infection, there is an inflammatory response Non-specific attack Phagocytes active ("eat" pathogen) 1 ST LINE OF DEFENSE: SURFACE COVERAGE: -The skin and mucous membranes protects the body from pathogens -Skin is a cellular, dead layer that is dry and is low in pH (kills many microorganisms) -oil/sweat glands and tears help wash bacteria away -Mucous membranes have lysozymes which breaks down bacteria -some cells contain cilia which helps to filter out pathogens or other particles 2 nd LINE OF DEFENSE: NON-SPECIFIC RESPONSE: -these are generalized, and random responses to pathogen infection -they consist of various plasma proteins and WBC’s such as: neutrophils, eosinophyls, basophils, mast cells, and macrophage

Inflammatory Response  Inflamation: is a response that is triggered by the damage of living tissues. It is a natural defense mechanism that protects you from injury and infection.  It localizes where the tissue damage is and eliminates it so that the body can begin in the healing process.  Some symptoms of this response include: change in blood flow, increased permeability of blood vessels, and the movement of proteins, fluids and white blood cells from circulation to the injured site.

Types of Inflammation  Acute Inflammation: This is inflammation that only lasts a few days  This is often benficial, and it usually causes uncomfortable sensations such as the itchiness of an insect bite or the pain of a sore throat  This sensation is temporary and only lasts until the healing is finished.  Chronic Inflammation: this is long term and can last for months or even years  the causes of this could be: failure to eliminate whatever caused acute inflammation, a chronic irritant of low severeness that persists, an autoimmune response which damages healthy tissue  Ex. Asthma, Tuberculosis, arthritis, Chron’s disease  Chronic inflammation over time can also cause harmful diseases like cancer, periodontitis, and hay fever

Sequence of Inflammatory Events  The sequence of inflammatory events is:  insult by trauma or initial entry of bacteria  platelet adhesion, vasoconstriction of vessels  Vasodilation of vessels causing increased blood flow (redness, local heat) to infected/damaged area  Filtration of fluid into tissues (causes swelling)  Exit of neutrophils (mature white blood cells) from vessels into tissues  Destruction of bacteria: phagocytosis with pus formation  Tissue repair

The Fever  -The Fever is another one of the body’s defense mechanisms to fight infections.  Occurs When your body temperature rises because of an infection,  Fevers are caused by chemicals called pyrogens flowing in the bloodstream. Pyrogens make their way to the hypothalamus in the brain, which regulates body temperature. When pyrogens bind to certain receptors in the hypothalamus, body temperature rises.  The main purpose of the fever is to raise the body’s temperature enough to kill a certain bacteria that are sensitive to temperature change.  The body’s normal temperature is about 37 degrees Celsius while an oral temperature of 37.8 degrees Celsius would be considered a fever

Question #1  If a person sprains their ankle, what type pf inflammation is most likely to occur?

Question #2  What are the main structures of the first line of defense?

Question #3  What is an example of something that would result in chronic inflammation?