what is the role fo blood in defending disease in the human body?

November 7, 2009 | By admin In Biology |
human disease
Onyx

including blood clotting, the role of phagocytesand natrual immunity

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4 Comments so far

  1. ♪Melody♫ on November 11th, 2009

    Platelets or thrombocytes are the cell fragments circulating in the blood that are involved in the cellular mechanisms of primary hemostasis leading to the formation of blood clots. Dysfunction or low levels of platelets predisposes to bleeding, while high levels, although usually asymptomatic, may increase the risk of thrombosis.
    Phagocytes engulf foreign bodies found in the body (such as bacteria) using a mechanism called endocytosis. They then digest the foreign body in the cell with enzymes. The remains are expelled from the cell.
    Natural immunity enables cells to defend the host from infection by other organisms, in a non-specific manner. This means that the cells of the innate system recognise, and respond to, pathogens in a generic way, but unlike the adaptive immune system, it does not confer long-lasting or protective immunity to the host. Innate immune systems provide immediate defense against infection, and are found in all classes of plant and animal life.

    For more info, look in your textbook :P

  2. Big J on November 11th, 2009

    Well, blood (to my knowledge) consists of four parts:

    Red Blood Cells
    White Blood Cells
    Plasma
    Platelettes

    The red blood cells carry oxygen throughout the body which is helpful in maintaining a good immune system. The plasma is the fluid in which the blood cells travel. In this fliud are also call platelettes, which activate when there is a cut on the skin. They clot up at the opening to keep any harmful bacteria from entering the body. And finally, the most important cell, the white blood cell. White blood cell are essential in fighting off harmful bacteria in the body in defensive for your immune system. When bad bacteria is present in the body, the white blood cells release an antibody that destroys them and then the white blood cells break down the bacteria.

  3. playpwnsu on November 14th, 2009

    Blood is a red lliquid substance, which includes oxygenated blood and deoxygenated blood.
    If you spin blood in a centrifuge it will disperse into solid and liquid plasma, the solid is red blood cells(erythrocyte), white blood cells(leukocyte), platelets(thrombocyte).
    Red blood cells carry oxygen to your body starting from the Aorta of the heart pumps through arteries, arterioles, capillaries(site of exchange), venules, and veins.
    Red blood cells include the globin, and the hemes, which carries 4 oxygen.
    Types of hemoglobins are oxyhemoglobin( carry oxygen), carbaminohemoglobin( carry CO2), deoxyhemoglobin( deoxygenated), reduced hemoglobin(carry H+).
    Leukocytes, white blood cells include T – lymphocyte and B-Lymphocyte, including helper T cells, memory T cells.
    Phagocytes engulf bacterias, viruses, antibodies attach to specific antigen for the phagocytes to destroy it.
    Once you have caught a particular disease, and you recover from it memory cells form so next time it comes you wont be affected, making you “immune”.
    Platelets are thrombocytes that are used for blood clotting, they are called to site of wound and release thromboplastin, then prothrombin, thrombin, fibrinogen, then fibrin.
    All these cells are formed in the Red bone marrow.

    hope it helps..

  4. knowitall on November 16th, 2009

    1) Pathogens at an infection site could potentially gain acess to the bloodstream and spread to other tissues/organs. Blood clotting on a small scale (i.e. clotting in small vessels at the infection site) prevents this spread from happening.

    2) Phagocytes are white blood cells (such as neutrophils and macrophages) that are able to engulf pathogens and then digest/destroy them. The immature dendritic cell is also a phagocyte, but the dendritic cell doesn’t destroy the pathogen–it processes it and displays portions of the pathogen on it’s cell surface. The dendritic cell matures (no longer phagocytoses) and travels to a lymph node. In the lymph node, a T cell can recognize and be activated by the pathogen fragment on the surface of the dendritic cell. This activates the adaptive immune response.

    3) Natural (innate) immunity includes phagocytes, but also other things. a) “Natural antibody” is made constantly by particular types of B cells even in the absence of infection. It’s activity and specificity for pathogens is weak, but it can hold off an infection while an adaptive immune response is being made. b) antimicrobial peptides are made by a variety of cell types, particularly mucosal epithelial cells. These peptides can bind to and neutralize particular pathogens. c) enzymes or other body secretions (such as stomach acid) can also kill pathogens before they cause illness. d) complement proteins in the blood can be activated on the surfaces of bacterial cells–this can lead to lysis of the bacteria. Complement activation also opsonizes bacteria (makes the bacteria easier for phagocytes to engulf). Some activated complement components are chemoattractant–they attract more white blood cells to the site of infection, thereby enhancing the immune response to infection.

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