Non-Specific Immune System (Prt. 1)
02-01-2003 09:35 PM
Non-Specific Immune System (Prt. 1)
This is an informative post yes, but also a little refresher course for myself. As a lot of you know, I will be 'selling' the gym real soon and looking for work else where. One of the potential careers I could follow is an Anatomy, Physiology, Body Composition and Human Nutrition Professor for a private University in northern WV......
Not Antigen Specific Iumme System & Mechanisms
First an 'antigen' must be defined. An antigen refers to an invading organism, or surface proteins on infected or mutated cells or cells foreign to that body. These can be things like transplants as an example.
The First Line of Defense
You skin. The skin is the greatest natural barrier because of its multiple layers of keratinized epithelial cells that are held together by tight cellualr junctions and protected by keratin (Duh). Another important aspect of the skin is the glandular secretions:
-Sepcial enzymes such as Lysozyme (bactericidal)
-Lactic acid- Part of sweat secretion and causes a very acidic Ph
-Antibodies secreted- IgA
Then you have mucuous membranes that also have tight cellular junctions and multiple layers of epithelia.
*Both mucuous and saliva contain lysozyme.
**In the case that something could or would break these barriers, they would be instantly exposed to macrophages in the underlying connective tissue.
*Neutrophils- Phagocytic, derived from the blood supply and brought into the tissue spaces via chemotaxis (chemical attraction to the infected site) and Diapedesis )squeezing between endothelial cells)
1.Phagocytosis- Engulfs & destorys antigen with lysosomal enzymes
2. degranulate- Lysosomes move to cell membrane and burst and release enzymes into tissue spaces; this creates a respiratory burst (also known as oxidation) which creates super oxide (free radicals). This O2 reacts with hydrogen ions and creates hydrogen peroxide (Cool **** aye? Gets better)
3. Will release an enzyme that reacts with Cl in the tissue and fluid and creates hypochlorite! (active ingredient in Chlorox)
*Eosinophils- Particularly active when in contact with allergy specific antibody-antigen complexes and certain parasites.
*Macrophages- These bastards function mainly by phagocytosis (see above) of things it recognizes as non-self, they are derived orignally from blood monocytes (although never found in the blood supply) and can be moving or fixed in tissue spaces. Its name can vary depending upon what tissue it resides in.
- Antigen Presentation- antigen is engulfed by phagocytosis, but not completely eliminated? Why? Watch- Portions of the antigen are "recycled" to the cell surface with specific other membrane proteins and so are "presented" to other immune cells to activate them as well. To make it short, the macrophages need help and more specific attack.
*Natural Killer Cells-These attack many different types of antigens. Could be microbes, infected cells, mutated cells, etc. It must first see inappropriate, non-self antigenic proteins on the cell surface.
Here's how it works
1. Natural Killer cell (NK) recognizes antigen and moves in to bind to it.
2. Lysosomes inside of the cell know to localize to that side of the cell and release perforin proteins into the extracellular space via exoctosis
3. Perforins insert themselves into the antigen by interacting with the antigen membrane. The antigen then lysis (blows up essentially) because of tonicity problems. The Nk cell itself is protected by protectin proteins.
A. A set of proteins that exist all the time in the blood plasma, but do not react with eachother until activated. Activation can occur via two pathways.
1. Classic- To activate this by this method, you need to have antigen/antibody complex. Antibody when bound to antigen changes shape and exposes area where complement proteins can bind thus the asskicking begins.
a. Also attracts macrophages
b. Also enhances inflammation response (more on this later)
2.Alternate pathway- No antibodies are needed, complement proteins can react with cell surface polysacchardies.
*Regardless of pathway, in the end two things occur:
1. Actraction and binding of phagocytes is enhanced
2. the remaining complement proteins come together and form a hole in the membrane known as membrane attack complex (MAC). Once again, the cell blows up (lyses)
Inflammation is simple and even if you could give a **** about the rest of this, you might be interested in this:
1. Chemicals are released from the damaged tissues, such as prostaglandins, potassium ions, etc.
2. This causes a release of histamin and hearin from mast cells. Histamine causes local vasodilation (swelling) and heparin temporarily prevents clotting.
3. Increases blood flow -> increases temperature which causes enzymatic reactions, increased activity of macrophages and may denature the foreign proteins
4. Microphages and macrophages and complement proteins do their thing. Lymphocytes may also be called in.
*Last but certainly not least
- Fever Generally caused by pathogems or macrophages releasing chemicals known as pyrogens which can stimulate the set-point of the hypothalamus to be increased. Fever is anything over 37 degrees centigrade or over 98.6 F. The body begins to shiver as you try to get warmer and skin vasoconstricts so you feel cool. Then the body catches up to SET POINT and you feel very warm and begin to sweat to cool down.....Thus the cold sweats when you're sick!
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