The immune system is composed of many interdependent cell types that collectively protect the body from bacterial, parasitic, fungal, viral infections and from the growth of tumor cells. Many of these cell types have specialized functions. The cells of the immune system can engulf bacteria, kill parasites or tumor cells, or kill viral-infected cells. Often, these cells depend on the T helper subset for activation signals in the form of secretions formally known as cytokines, lymphokines, or more specifically interleukins. The purpose of this article is to review the organs, cell types and interactions between cells of the immune system as a commentary on their importance and interdependence on the T helper subset. Such an understanding may help comprehend the root of immune deficiencies, and perceive potential avenues that the immune system can be modulated in the case of specific diseases.
The Organs of the Immune System
Bone Marrow -- All the cells of the immune system are initially derived from the bone marrow. They form through a process called hematopoiesis. During hematopoiesis, bone marrow-derived stem cells differentiate into either mature cells of the immune system or into precursors of cells that migrate out of the bone marrow to continue their maturation elsewhere. The bone marrow produces B cells, natural killer cells, granulocytes and immature thymocytes, in addition to red blood cells and platelets.
Thymus -- The function of the thymus is to produce mature T cells. Immature thymocytes, also known as prothymocytes, leave the bone marrow and migrate into the thymus. Through a remarkable maturation process sometimes referred to as thymic education, T cells that are beneficial to the immune system are spared, while those T cells that might evoke a detrimental autoimmune response are eliminated. The mature T cells are then released into the bloodstream.
Spleen -- The spleen is an immunologic filter of the blood. It is made up of B cells, T cells, macrophages, dendritic cells, natural killer cells and red blood cells. In addition to capturing foreign materials (antigens) from the blood that passes through the spleen, migratory macrophages and dendritic cells bring antigens to the spleen via the bloodstream. An immune response is initiated when the macrophage or dendritic cells present the antigen to the appropriate B or T cells. This organ can be thought of as an immunological conference center. In the spleen, B cells become activated and produce large amounts of antibody.
The immune system is made up of a network of cells, tissues, and organs that work together to protect the body, and it defends the body from “foreign invaders.” Immunity can be divided in two three different defenses, and these are defined as first, second and third lines of defense. The first line of defense for the immune system is the primary defense against pathogens entering the body from the surface in order to prevent the start of disease and infection. Some examples of the first line of defense is the skin, protecting the external boundaries of the body, and the mucous membranes, protecting the internal boundaries of the body. Although the skin and mucous membranes work on the internal and external boundaries, they both release chemicals
Stem cells are the building blocks of the human body. Embryos consist of unspecialized stem cells that transform into the various specialized cells in the body such as cardiac, muscle or bone cells. Fetuses also have stem cells. However, the stem cells are divided into types like muscle, bone or nerves and don't perform a specialized function. Surprisingly, adult bodies also contain stem cells. In adults, stem cells are undifferentiated but limited to specific tissue type. When needed, the stem cells transform into the cells needed for repair and maintenance. The most common source of adult stem cells is bone marrow. Researchers also acquire stem cells from umbilical cords. Without stem cells, embryos could not develop into fetuses and adult
The body is composed of cells, which form the basic unit of life. Unique cells found in the body are the stem cells. These cells are biological cells that are not specialized for particular functioning in organisms. They can be distinguished since they have the ability to differentiate or divide into multiple body cells, and their ability to replicate self. They are unique in the way they can renew themselves by undergoing cell division when inactive for a long period. It is also possible to induce stem cells to organs or tissue cells under some conditions. When the cells divide, they replenish the cells in a living organism. They serve as an internal system that repairs and replaces the tissues that are worn out.1 Dividing cells may remain as stem cells or become specialized in their functions, for instance red blood cells, brain or muscle cells.
When red blood cells start out, they are shaped like flat discs. Over time, when passing through the spleen, pieces of the membrane are removed, causing the red blood cells to become round in shape, hence the term Spherocytosis (Seattle Childrens). When red blood cells enter the spleen, the cells undergo hemolysis. Hemolysis in hereditary spherocytosis results in the interplay of an intact spleen and an intrinsic membrane protein defect (Medscape). The breakdown of red blood cells is called hemolytic anemia (Wint Carmella).
Each part of the immune system plays a certain role in keeping pathogens out of the body. Bone marrow is the soft material found inside bones. It is used to make the lymphocytes needed in the body every day. Located above the heart, the thymus is a gland that helps produce a special kind of lymphocyte.
These functions are mineral storage, energy storage, and hematopoiesis. In regards to metabolic reaction, this system has extremely critical functions that are important for the entire body. The cells in bone tissues have chemical processes that produce the energy and substance needed to maintain life. The first function is the role of bone matrix. (Baumie) The bone matrix plays the role as a supply for minerals that are important to the body functions. The two main minerals are calcium and phosphorus. To keep the stability that is needed to support physiological processes the minerals can be released back into the bloodstream. (Baumie) For example, calcium ions are necessary for muscle contractions and flow of other ions that take place in the transferral of nerve impulses. (Baumie) The next function that is important for homeostasis is hematopoiesis. This process is responsible for producing new blood cells in the body. Hematopoiesis has three types of blood cells and they are able to become more than one type of a cell. (Baumie) Cells that are capable of producing more cells of the same type are called stem cells. The stem cells that are a result of hematopoiesis are Pluripotent stem cells, multi potent stem cells, and committed progenitor cells. Stem cells are not the only production from this process. The three types of white blood cells that are also produced
The spleen is a fist-sized, spongy organ located behind the stomach (removed in this illustration), just under the diaphragm. Part of the lymphatic system, the spleen is composed of two types of tissue. White pulp produces lymphocytes, which release antibodies into the bloodstream to combat infection. More prominent is the red pulp, in which macrophages filter broken cells, parasites, bile pigments, and other useless substances from the blood. Iron from broken red blood cells is stored in the spleen for later use. Despite this variety of functions, an injured or diseased spleen can be removed in adults without great consequence.
The structure and function of our immune systems is a great help for our body to keep all of us healthy. Our immune system has a specific structure that it should maintain. There are also organs that play a major part for the health of our immune system. These organs are called lymphoid organs because of the lymphocytes that inhabit that area. (white blood cells) Bone marrow is also one of the key elements for the immune system, this is where all of our blood cells are being made along with the white blood cells. With the help of the bone marrow, white blood cells are constantly traveling throughout our bodies using the blood cells for help. Another structure that is important for our immune system is lymphoid tissue. Lymphoid tissue acts as a gateway into our bodies that help to prevent incoming germs.
The spleen, an organ on the left side of the abdomen across from the liver, is responsible for filtering the blood for infections and other abnormalities.
The spleen stores blood. The spleen is made up of two types of tissue which consist of the red pulp and white pulp. The function of the red pulp is to store and remove red blood cells. The white pulp consists of localised areas of lymphoid tissue within the spleen and produces the lymphocytes. ( Reeder et al., 2009).
Seattle Education Project. (2013, November). STEP: The Immune System - An Overview, [Online]. Available: http://www.thebody.com/step/immune.html [11/12/14].
A simple definition for the circulatory system would be that it is the main transportation and cooling system for the body. Red Blood Cells have an important job in this system in that they carry all sorts of packages that are needed by all the cells in the body. Red blood cells carry oxygen and nutrients to the cells, which is needed in order for cells to survive. Besides red blood cells there are also White Blood Cells moving in the circulatory system. White Blood Cells can be considered as the paramedics, police and street cleaners of the circulatory system. Anytime we have a cold, a cut, or an infection the white blood cells go to work. From research I also came to find out that white blood cells also help cuts or wounds to heal quicker. Something I did not know was that puss which appears during an infection are actually white blood cells that are attacking the infection.
Adaptive immune system happens much quicker to the presence of an “infection creating potent mechanisms for neutralizing or eliminating the microbes. There are two types of adaptive immune responses: humeral immunity, mediated by antibodies produced by B lymphocytes, and cell-mediated immunity, mediated by T lymphocytes.”
We are always hearing on the news and in newspapers about children catching diseases and often dying from them. Why is this happening when all of these diseases are easily preventable by simply being immunised, why aren’t parents getting their children Immunised, is it for religious beliefs or just carelessness. What ever their reason may be is it really good enough, because why would anyone rather let their child be able to catch and spread a deadly disease then have them Immunised, so Immunisation should be made compulsory for all children.
The human body is very complex. It is like a job. You have to do a million things in one day to make it through the day. The body uses nine systems to do all of those jobs. They all have separate functions, but some work together. Each system is also made up of organs. There are many ways to care and protect the systems from the many different problems they can have. There are also many interesting facts about each system.