The Human Immune System Of Multiple Structures

The immune system is made up of several types of cells that work together to fight infections. Lymph cells (called lymphocytes) are the main type of cell in the adaptive immune system. There are 2 types of lymph cells: T cells and B cells. When B cells respond to an infection, they change into plasma cells. The plasma cells are found mainly in the bone marrow—the soft, inner part of some bones. The plasma cells

The immune system plays a vital role in helping the body to fight diseases, as well as pathogens, the disease-causing factors. It is mainly composed of the tonsils and adenoids, the lymph nodes and lymphatic vessels, the spleen, appendix, and bone marrow. The main purpose of the immune system is to assist the body in its struggle to maintain optimal health.

a. This function is mediated by T cells and B cells (memory cells) in our body via adaptive immunity. The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory, where each pathogen is “remembered” by a signature antigen. The adaptive immune response is antigen-specific and requires the recognition of specific “non-self” antigens during a process called antigen presentation. Antigen specificity allows for the generation of responses that are tailored to specific pathogens or pathogen-infected cells. The ability to mount these tailored responses is maintained in the body by memory cells. Should a pathogen infect the body more than once, these specific memory cells are used to quickly eliminate it. So basically killer T cells will identify antigens present on foreign cells. These antigens are not found in any of the cells inside our body. Therefore, T cells will identify them and kill them.

CD4 is a glycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. HIV infects cells of the immune system called T lymphocytes (T cells) and macrophages. HIV has an envelope and contains two copies of single-stranded RNA as the genome. Within the viral capsid are important viral enzymes called reverse transcriptase, integrase, and protease. The HIV virus has a spike protein that is called gp120, and the host cell receptor is CD4+. HIV belongs to a class of viruses called retroviruses. Retroviruses are RNA viruses, and to replicate or reproduce, they must make a DNA copy of their RNA through transcription and translation. It is the DNA genes that allow the

i. HIV is a virus that kills cells in our immune system, which protects us from

The organs that make up the lymphatic and immune system are the tonsils, spleen, thymus gland, lymph nodes, and lymphatic vessels. White blood cells (leukocytes), red blood cells (erythrocytes), plasma, and platelets (thrombocytes) make up the blood. Lymphocytes are leukocytes (white blood cells) that help the body fight off diseases. Two types of lymphocytes are B cells and T cells. Lymphocytes recognize antigens, or foreign substances/matter, in the body. Lymphocytes are a classification of agranulocytes, or cells (-cytes) without (a-) granules (granul/o) in the cytoplasm. B cells are created from stem cells, which are located in the bone marrow. B cells respond to antigens by becoming plasma cells. These plasma cells then create antibodies. Memory B cells produce a stronger response with the next exposure to the antigen. B cells fight off infection and bacteria while T cells defend against viruses and cancer cells. A hormone created by the thymus gland called thymosin changes lymphocytes into T cells. The thymus gland is active when you are a child and slowly shrinks, as you get older. T cells bind to the antigens on the cells and directly attack them. T cells secrete lymphokines that increase T cell production and directly kill cells with antigens. There are three types of T cells: cytotoxic T cells, helper T cells, and memory T cells.

They are known as T- Lymphocytes and B-Lymphocytes. B-cells are usually distinguished with humoral immunity because b-cells circulate freely through the lymph system. Whereas T-cells are distinguished by humoral immune response because they act with antigens within other cells. Once these lymphocyte have been produced with the help of bone marrow stromal cells (which are a type of stem cell that is present in red bone marrow) they are released into the blood stream where they travel up to the thymus, and other lymphoid organs. When B-cells, also known as memory cells, leave the bone marrow, they become activated (true b-cells) This process involves the addition of a membrane protein known as immunoglobin M. (IgM) This membrane protein acts a receptor for antigens. Therefore they can said to be the binding site for antibodies. Once an antigen attaches itself to IgM receptor, a signal transduction pathway occurs through tails that descend down into the cells cytoplasm causing them to release antibodies. The second cell type, T-cells, are produced in the bone marrow, through the the same way B-cells are produced. The only difference is they mature in the thymus. This occurs because they undergo genetic recombination of their alpha

They go through negative selection after V(D)J recombination where the self-reacting cells are eliminated. Positive selection is in the periphery and where B cells become mature B-cells. Unlike T-cells, B-cells also go through hypermuation and class switching in the lymph nodes after they are activated. This helps them be more specific for antigens. B-cells either proliferate into memory B-cells or plasma cells that secrete antibodies. Antibodies opsonize, neutralize or fight by complement fixation against the virus. The memory cells are used if an infection of the same virus occurs

For example, Wiskott-Aldrich and Beckwith-Wiedemann syndrome are known to alter the immune system. The immune system is a complex system that functions to protect our bodies from infection and disease. The bone marrow produces cells that later mature and function as part of the immune system. One theory suggests that the cells in the bone marrow, the stem cells, become damaged or defective, so when they reproduce to make more cells, they make abnormal cells or cancer cells. The cause of the defect in the stem cells could be related to an inherited genetic defect or exposure to a virus or toxin. Exposures to certain viruses Epstein-Barr virus and HIV, the virus that causes AIDS, have been linked to an increased risk of developing certain childhood

Human immunodeficiency virus (HIV) infects the cells of the immune system. In particular, HIV attacks and destroys the T helper lymphocytes, or T-cells, which are crucial to the immune system and immune response. (These cells are also called CD4-positive lymphocytes because HIV uses the protein CD4, present on the surface of the cell, to attach itself and pry its way into the cell.) Each day, your body produces millions of CD4+ T-cells to help maintain your immunity and fight off invading viruses and germs. Once HIV is in your body, the virus is able to copy itself over and over, increasing its ability to kill CD4+ T-cells. Soon, infected cells outnumber healthy T-cells.

The Human Immune system is made up of a variety of chemical and cellular components that are classified as either innate or adaptive immunity. The cellular immune response to the bubonic plague is carried out through the innate response as the bacterium is able to avoid the adaptive response by infecting macrophages in the host’s body. Similarly, the immune response to HIV infection is not able to reach the adaptive response, as the virus infects the body and destroys vital CD4 cells which in turn damage the immune system itself. Furthermore, the immune system relies heavily on the action of B and T cells, which are antigen-specific cellular immune responses to battle the HIV virus. Though it is unable to completely rid the host of the virus,

Lymphocytes are a type of white blood cell, which are an important part of the immune system. Lymphocytes can defend the body against infection because they can distinguish the body’s own cells from foreign ones. Once they recognize foreign material in the body, they produce chemicals to destroy that material. Two types of lymphocyte are produced in the bone marrow before birth.

The next cells are the T cells. There are many different types of T-cells. One is the Killer T-cell. They can recognize invaders with feelers on the outside of the cell and if the cell is infected, it can destroy the cell. Another type is the helper T-cell. The helper t-cell functions more as support. It matures B-cells and tells them to make antibodies by secreting a protein. A helper t-cell also activates the killer t-cell. The last major t-cell is the memory t-cell. If you get sick, the memory t-cell will remember the antigen and will the immune system be able to defeat the same disease faster. The next cell is the Natural Killer Cell. These cells are lymphocytes that destroy viruses by releasing a protein that makes the affected cell “program” itself for death. The process it destroys itself is called apoptosis. (Kidshealth.org)

HIV primarily attacks CD4+ helper T cells by recognizing and binding the CD4 receptor on the surface of the T cells. It can sometimes invade monocytes and macrophages as well since they also have some CD4 receptors on their surfaces. Tumor necrosis factor alpha (TNF-a) and interleukin-6 (IL-6) are secreted at higher levels in infected individuals, and this may help activate the HIV proviruses (latent viruses). HIV has a high mutation rate during replication with the reverse transcriptase, which is why it is able to readily evade our immune response.

Our immune system is the second most complex system in our body. It is made up of organs, cells and proteins that work together to protect our bodies from harmful bacteria, viruses or other microorganisms that can cause diseases. Usually we don’t notice our immune system defending us against pathogens, but if the pathogen (harmful microorganism) is aggressive or if our body hasn’t ever come into contact with it, we can get sick. The jobs of our immune system are to recognise pathogens, as well as neutralise and remove them from our body. Our immune system also has to fight our own cells if they have changed due to an illness, for example, cancer. (1)