Tuesday, February 5, 2008

Immune/ Lymphatic system 1

Today we learned about the immune and lymphatic system.

There are many avenues of attack for foreign substances to enter your body.
  1. digestive system
  2. respiratory system
  3. urogenital tract
  4. break in the skin
Once their in your body they can either use the circulatory system or the lymph system to go around your body. A body needs an immune system to protect it from viruses, bacteria, fungi and protists that are going to use the body as a tasty nutrient & a vitamin-packed meal. Also your body can be attacked from the inside by abnormal body cells like cancers. The lymph system is made fore the production and transportation of leukocytes and to trap foreign invaders. Only white blood cells travel through this system. It consists of lymph vessels which are intertwined amongst blood vessels , and lymph nodes which are made to collect foreign invaders.

Red and white blood cells are made from pluripotent stem cells in the bone marrow. These stem cells are then made into lymphoid stem cells and myeloid stem cells. The myeloid stem cells make red blood cells , basophils, eosinophils, neitrophils, monocytes, and platelets. Lymphoid stem cells make either B-Cells or T-Cells. B & T cells are the true immune system.

The first line of defense

Broad, external defense. such as walls and moats. this is the skin and mucous membranes. The skin includes external and external skin.

The physical and chemical defenses are non specific. The external barrier are epithelial cells and mucus membranes such . Examples are the skin, the respiratory system, the digestive system and the urogenital tract.

The chemical carriers on the epithelium are skin and mucous membrane secretions. Sweat, tears, mucus, saliva, stomach acid and anti-microbial proteins (such as lysozyme enzyme)

The Second Line of defense inclcludes internal, broad range patrol by many different cells and proteins such as mast cells, monocytes, macrophage and natural killer cells.

Leukocytes or phagocytic WBC's. Their attracted by a chemical signal released by damaged cells. Neutrophils are the most abundant and have a three day life span. Macrophages are "big eaters" and are long-lived. Natural killer cells destroy virus-infected cells and cancer cells.

In order to kill cells tho have gone bad , natural killer cells perforate cells, by releaseing perforin ( a protein) into the membrane of a target cell.. This forms a pore allowing fluid to flow into the cell. The cell then ruptures or lysis. This is call apoptosis. As Ms. Foglia says, its like "causing a cell to commit suicide"

Anti - microbial proteins awork as a complement system. 20 proteins circulating in blood plasma attack baterial and fungal cells. This forms a membrane attack complex which perforates target cells which also leads to apoptosis.

Inflammatory response is when damage to tissue triggers local non-specific inflammatory response. The cells then release histamines and prostaglandins. Capillaries then dilate and become more permeable This : increases blood supply, delivers WBC, RBC, Platelets & clotting factors. This accounts for swelling, redness and heat of inflammation & infection.

i cant get pictures because my computer is being difficult, i'm sorry this was boring, BUT tomorrow's sherpa will beeeeeeee...... KIM :)


No comments: