BLOOD AND BLOOD COMPOSITION

The blood is the transport tissue of the body. It is a tissue with a fluid matrix, where millions of cells exist. The liquid portion (matrix) of the blood is called plasma. Plasma is a straw-colored liquid made of mostly water. The formed elements that are suspended in the plasma include erthrocytes (red blood cells), leukocytes (white blood cells),
thrombocytes (platelets). Two types of connective tissue produce blood cells for the body--myeloid tissue and lymphatic tissue. Many of the cells found in blood are the cellular units of the immune system.

ERTHROCYTES (red blood cells)
The primary function of erthrocytes is to transport oxygen to other cells of the body. There are proportionally, many more erthrocytes in the body than leukocytes. Every day, approximately 100 billion erthrocytes die.
They have a very short lifespan.

LEUKOCYTES (white blood cells)
Leukocytes, in general, defend the body from microorganisms.
One type: basophils play some sort of role in allergic responses.
LEUKOCYTES (white blood cells)Another type: Lymphocytes, play a major role in immune response. They are small, round cells that circulate in both the blood and the lymph. They are found in large numbers in organs of the lymphatic system, in particular the lymph nodes.

When a foreign microorganism enters the body, the antigen on the organism signals the invasion. Both B-cells and T-cells are able to recognize antigens, but B-cells are capable of producing the antibodies that can recognize and attach to the antigen. Both B-cells and T-cells are stimulated by the presence of an invading microorganism in the bloodstream, but they have different ways of attacking the invaders. The T-cells are stimulated when they are alerted to an invasion. They then leave the comfort of the thymus and flow through the lymph or blood, arriving at the site of the antigen. Once there, the T-cells interact one-on-one with the foreign cells, almost like soldiers on a battlefield. Most often, the T-cells kill the invaders and keep you from becoming sick.
This process is called cell-mediated immunity.
Germs: Germs such as viruses and bacteria (shown in blue) can get into the blood stream. Defenders called antibodies, can latch onto the germs so white blood cells (shown in orange) can kill the germs.

THROMBOCYTES (platelets)
The platelets are responsible for clotting the blood. If you get a cut on your skin, and your immune system is working correctly, you will stop bleeding and a scab will form. That is because your thrombocytes are stopping the blood from continuously bleeding out. 200,000 to 300,000 Platelets… These brownish-yellow bits of cells help blood to form clots. Activated platelets work at reducing blood flow. Unactivated platelets await their “call” to heal.

Fibrinogen This substance causes platelets to stick together at the site of a cut. Step 2: Forming a clot ( a natural plug that stops the flow of blood) And in time, converting into fibrin threads

Plasma