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The Organs Of The Immune System

Immunity is the mightiness of an fauna to struggle against infections together with diseases. The immune organisation consists of a complex network of organs, cells, together with molecules. They piece of job together to defend the trunk from illness causing organisms (bacteria, viruses, fungi, together with parasites). The immune organisation protects the trunk from pathogens together with toxins that could disrupt the trunk  homeostasis.

Functions of immune system

1.       Provides defenses against pathogens
2.       Removes dead or worn out cells similar RBCs
3.       Identifies together with destroys abnormal cancer cells
4.       Protects from autoimmune diseases
5.       Rejects tissues cells of unusual antigens.

Characteristics of the immune response

1. Specificity: the mightiness to distinguish betwixt antigens
2. Adaptiveness: the mightiness to answer to previously unseen molecules.
3. Recognition of self together with non-self: the mightiness to recognize together with answer to molecules that are unusual or ‘non-self ‘and the molecules that are ‘self’.
4. Memory: the mightiness to retrieve previous contact amongst a unusual molecule together with answer to it inward a learned manner.

The primary features of Immune organisation includes designing recognition (anomaly detection); distributed control; diversity, learning, memory, redundancy, robustness, characteristic extraction, multilayered together with adaptive.

Parts of vertebrate Immune system

• Natural or innate or non-adaptive or non-specific immune system
• Acquired or adaptive or specific immune system

Immune Mechanisms

First lines of defence are the physical barriers which include the skin, urine, tears, cilia, mucosal membrane, etc. The peel provides an almost impenetrable biological barrier. Lysozyme is an enzyme flora inward tears together with saliva that tin laissez passer on notice interruption downward unusual agents. Mucus together with cilia flora inward the olfactory organ together with pharynx tin laissez passer on notice grab unusual agents together with therefore sweep them exterior via coughing, sneezing together with vomiting.
Second lines of defence are the macrophage system, complement, fever, interferon together with inflammation. A instant describe of piece of job of defense is the specific or adaptive immune organisation which may accept days to answer to a primary invasion. The production of antibodies together with cell-mediated responses may occur inward which specific cells recognize unusual pathogens together with destroy them. The response is oft to a greater extent than rapid because of the activation of retentivity B together with T cells. The cells of the immune organisation interact amongst i about other yesteryear a variety of dot molecules. These signals may hold out proteins such every bit lymphokines, cytokines together with chemokines which receive cells of the immune system
Third lines of defence are the specific organisation likewise known every bit acquired or adaptive immunity. The specific organisation consists of B cells (humoral), together with T cells (cell-mediated).

Kinds of lymphoid Organs

Primary/central lymphoid organs  

The os marrow together with the thymus constitute the primary lymphoid organs. Both B-lymphocytes together with T-lymphocytes are produced from stalk cells inward the os marrow. B-lymphocytes mature inward the os marrow spell T-lymphocytes migrate to the thymus together with mature there. After maturation, both B-lymphocytes together with T-lymphocytes circulate through together with accumulate inward secondary lymphoid organs.

Bone marrow

It is a fundamental organ where all the immune cells are born together with entirely B cells mature (process termed every bit B lymphopoiesis). THYMUS is the other fundamental organ inward which T cells mature (T lymphopoiesis).
Bone marrow is a spongy tissue flora inside bones. All blood cells are produced inside the os marrow. The os marrow of an adult produces most 3 i grand 1000 reddish blood cells together with 120,000 white blood cells every second. All these cells originate from a little population of stalk cells, which may hold out every bit few every bit i inward a i grand 1000 of the os marrow cells.


It is a flat, bilobed organ situated to a higher identify the see together with below the thyroid gland. Each lobe is surrounded yesteryear a capsule together with is divided into lobules. The lobules are separated from each other yesteryear strands of connector tissue called trabeculae. Each lobule is organized into 2 compartments: the cortex (outer compartment) the medulla (inner compartment). In the cortex, the network is densely packed amongst thymocytes. These cells are less dense inward medulla. In medulla, the epithelial cells are to a greater extent than visible together with Hassal's corpuscles are introduce (function unknown). The thymus is at its largest relative size at nascence together with its largest actual size is at puberty. After puberty the thymus begins to shrink. Precursor T cells acquire inward thymus from the blood (there are no afferent lymphatic vessels) together with mature into functional T lymphocytes.
The consummate procedure of thymic instruction is a two-step procedure inward which Thymic cortical epithelial cells business office every bit the effector cells inward a procedure known every bit positive selection. Positively selected thymocytes must travel through a instant stage of alternative known every bit negative selection. The stromal cells secrete thymic hormones which are of import inward T prison theater cellular telephone maturation e.g., alpha- 1- thymosin, beta - 4- thymosin, thymopoietin together with thymulin.

Secondary /peripheral lymphoid tissue

The secondary lymphoid organs include lymph nodes together with the spleen, every bit good every bit lymphoid tissues. The lymphoid tissues include the tonsils, the appendix, together with the Peyer's patches inward the lining of the little intestines (gut-associated lymphoid tissue or GALT). The lymphoid tissue flora beneath the mucous membranes of the bronchi (bronchial-associated lymphoid tissue or BALT). The lymphatic tissue flora inward the mucous membranes (mucosa-associated lymphoid tissue or MALT). The lymphatic tissue flora beneath the peel (skin-associated lymphoid tissue or SALT).

Lymph nodes 

They are small, bean-shaped structures laced along the lymphatic vessels, amongst clusters inward the neck, armpits, abdomen, together with groin. Each lymph node contains specialized compartments where immune cells congregate, together with where they tin laissez passer on notice encounter antigens. The immune cells together with unusual particles acquire inward the lymph nodes via incoming lymphatic vessels. All lymphocytes acquire out lymph nodes through outgoing lymphatic vessels.
The lymph node consists of 3 regions: cortex is the outermost layer which contains generally B lymphocytes, plus both follicular dendritic cells together with macrophages all arranged inward clusters called primary follicles. Following antigenic stimulation the primary follicles travel secondary follicles consisting of concentric rings of densely packed lymphocytes, macrophages together with dendritic cells. The germinal centers incorporate large proliferating B lymphocytes together with plasma cells interspersed amongst macrophages together with dendritic cells. The paracortex is the layer only beneath the cortex. This portion is sometimes called the T theme portion of the lymph node. It is an expanse populated amongst T lymphocytes together with likewise interdigitating dendritic cells. It is an of import site for T prison theater cellular telephone activation yesteryear these APCs. The medulla is the inner most region, to a greater extent than sparsely populated yesteryear cells. Many of the cells are plasma cells; activated T helper together with T cytotoxic cells are likewise present. In addition, in that place is a high concentration of immunoglobulin inward this portion due to the large population of plasma cells. The "swelling of lymph nodes" is the huge growth inward the number of lymphocytes is due to: proliferation of lymphocytes inside the lymph node, influx of lymphocytes from the circulatory organisation together with antigenic stimulation.


The spleen is the largest of the lymphoid organs which is located at the upper left of the abdomen. Like lymph nodes, the spleen contains specialized compartments where immune cells get together together with work, together with serves every bit a coming together Blue Planet where immune defenses aspect antigens. It is surrounded yesteryear a capsule, which sends trabeculae into the interior to shape a compartmentalized structure. There are 2 types of compartments: reddish pulp together with white pulp. Red pulp is a network of sinusoids populated amongst macrophages together with numerous erythrocytes. This is the site where former RBCs are destroyed together with removed. White pulp surrounds the splenic arteries, forming a periarteriolar lymphoid sheath (PALS) populated mainly yesteryear T lymphocytes. Clusters of B lymphocytes inward the white pulp shape primary follicles occupying a to a greater extent than peripheral position. Upon antigenic challenge, these primary follicles prepare into characteristic secondary follicles containing germinal centers.
The immune functions of spleen include: proliferation of lymphocytes, production of humoral antibodies together with removal of macromolecular antigens from the blood.
The hematopoietic functions include: formation of blood cells inward fetal life, removal together with devastation of senile, damaged together with abnormal RBCs together with platelets together with the retrieval of the atomic number 26 from hemoglobin.

Lymphoid tissues 

They are clumps of lymphoid tissue are flora inward many parts of the body, particularly inward the linings of the digestive tract together with the airways together with lungs-territories that serve every bit gateways to the body. These tissues include the tonsils, adenoids, together with appendix.Peyer's patches are areas of lymphoid tissue located inward the wall of the intestine, together with inward about mammalian species such every bit sheep, cattle together with rabbits. Peyer's patches receive got a business office similar to the bursa of fabricius of birds together with os marrow of other mammals: B prison theater cellular telephone differentiation together with maturation.

Functions of lymphatic organs

They generate immuno-competent lymphocytes, concentrate antigens into lymphoid organs, together with circulate lymphocytes through lymphoid organs, exposing antigen to a variety of lymphocytes together with deliver antibodies together with effector T cells to the blood together with tissues.



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