Immune system

---

The immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful pathogens, such as bacteria, viruses, and parasites. The main goal of the immune system is to identify these foreign invaders, neutralize or destroy them, and ultimately protect the body from infection and disease.

The immune system can be divided into two main categories:

1. Innate immunity: This is the first line of defense and is present at birth. It provides a general, non-specific response to pathogens and includes physical barriers, such as the skin and mucous membranes, as well as various cells and proteins that can recognize and respond to a wide range of pathogens.
2. Adaptive immunity: This is a more specialized and targeted response that develops over time as the body is exposed to different pathogens. Adaptive immunity relies on specific cells, such as B and T cells, which can recognize and remember specific pathogens, allowing for a faster and more effective response during subsequent encounters.

Here are some key components of the immune system:

• White blood cells (leukocytes): These cells circulate in the blood and lymphatic system and are involved in both innate and adaptive immune responses. There are several types of white blood cells, including neutrophils, monocytes, lymphocytes, and more.
• Antigens and antibodies: Antigens are molecules on the surface of pathogens that can be recognized by the immune system. Antibodies are proteins produced by B cells (a type of white blood cell) in response to a specific antigen. Antibodies can bind to the corresponding antigen and help neutralize or destroy the pathogen.
• T cells: T cells are a type of white blood cell that plays a central role in adaptive immunity. There are several types of T cells, including helper T cells, which activate other immune cells, and cytotoxic T cells, which can directly kill infected cells.
• B cells: B cells are another type of white blood cell involved in adaptive immunity. They produce and secrete antibodies specific to a particular antigen, aiding in the neutralization or destruction of pathogens.
• Phagocytes: These are cells, such as macrophages and neutrophils, that can engulf and digest pathogens, dead cells, and debris. They play a crucial role in the innate immune response.
• Cytokines: Cytokines are small signaling proteins that help regulate and coordinate the immune response. They are produced by various immune cells and can have a wide range of effects, such as promoting inflammation, activating immune cells, or inhibiting viral replication.

In summary, the immune system is a complex and highly coordinated system that protects the body from harmful pathogens. It relies on both innate and adaptive immune responses, involving numerous cells, proteins, and signaling molecules that work together to identify, neutralize, and destroy foreign invaders.

---

The immune system is a system of biological structures and processes that protects the body from diseases and pathogens. It consists of the following major parts:

1. White blood cells: White blood cells, or leukocytes, are cells of the immune system that circulate in the bloodstream and lymph. They include lymphocytes (B cells, T cells, and natural killer cells), neutrophils, eosinophils, basophils, and monocytes. These cells work together to detect and neutralize pathogens that enter the body.
2. Lymphatic system: The lymphatic system is a network of vessels and organs that produce, store, and carry white blood cells. It includes the thymus, spleen, and lymph nodes which produce and store lymphocytes and also filter pathogens from the lymph fluid.
3. Bone marrow: Bone marrow produces the white blood cells that circulate in the bloodstream and protect the body. Bone marrow stem cells can produce new red and white blood cells to combat infection or replace old cells.
4. Complement system: The complement system consists of small proteins that circulate in the blood and help antibodies and white blood cells eliminate pathogens. It creates holes in the cell membranes of pathogens, marking them for destruction.
5. Inflammatory response: The inflammatory response brings immune cells to the site of an infection or injury to isolate and neutralize pathogens. It causes the characteristic redness, swelling, heat, and pain associated with wounds and infections.

The immune system protects the body through this coordinated defense system involving many cell types and organs. When it is functioning properly, it can detect and eliminate a wide variety of pathogens to prevent disease. However, immune system disorders can lead to increased susceptibility to infections, autoimmune diseases, and other problems.

---

---

Transcript:-
The immune system is an integrated network of organs, tissues, cells, and cell products such as antibodies that protect the body from pathogens and other foreign substances. Blood and lymph are the two fluid systems of the body. The blood is a red vascular tissue consisting of the liquid called plasma and the cells red blood, cortisols, RBCs, white blood, cortisols, WBCs, and platelet.

The lymph is a colorless vascular fluid having fluid matrix called plasma and white blood cortisols. Both these components of lymph escape from the blood through the thin walls of the capillaries, the plasma by ultra filtration or diffusion under pressure, and the cortisols by a me boy movement. The plasma and the corpus cells, RBCs and WBCs form the main components of blood.

Red blood cortisols are red in color due to the presence of a respiratory pigment. Hemoglobin, which is responsible for transporting oxygen to and carbon dioxide away from all parts of the body. RBCs are circular, dislike, biconcave, and without nuclei. These are about 7.7 microns in diameter. The number of RBCs is usually 5 million per cubic millimeter of.

The WBCs are devoid of hemoglobin and hence are colorless. Leukocytes are larger than RBCs in size and may range from 10 to 20 microns in diameter. They vary a number from 6,000 to 10,000 per cubic millimeter of blood. WBCs are of two main types, the granulocytes or polymorph, nuclear leukocytes, and a gracy.

Granulocytes are cells that contain granules in the cytoplasm. For example, neutrophils, eosinophils, and basophils. Neutrophils are large cells whose granules stain lilac with ne neutral dyes. They contain a nucleus that has three or more lobes. The lobes joined together by hairlike chromatin. These cells constitute about 60 to 70% of wbc.

Eosinophils have coarse granules in the cytoplasm, which stain deep red with eosin and the nucleus is bi lobed. These make up about 4% of WBCs. Basophils have coarse granules, which stain deep blue with a basic stain, and the nucleus is small without differentiation or partially differentiated into lo.

These constitute 0.5 to 1% of the WBCs. A granulocytes are without granules in the cytoplasm. These include lymphocytes and monocytes. Lymphocytes have large rounded or oval nuclei, which stain deep purple with right stain. And the Cytoplasm app pale blue color. These constitute 20 to 35% of wbc.

Monocytes are very large cells about two to three times as large as RBCs. The nucleus is large and slightly kidney shaped, and the cytoplasm stains pale blue. These constitute three to 8% of the WBCs. WBCs defend the body by destroying pathogens, either by their phagocytic activities or by forming antibodies.

The blood platelets are fragmented bodies without nuclei. The number of platelets varies from 200,000 to 300,000 per cubic millimeter. These play an important role in blood coagulation. Lymph is a fluid tissue which bathes all the cells of the body and acts as a connective link between the blood and body.

Lymph is formed when interstitial fluid proteins extravasated, WBCs microorganisms, and absorbed fat passed through the capillary wall into the tissue tissue spaces. By ultra filtration, the lymph is continually drained from the tissue tissue spaces. Through a system of tubules known as the lymphatic system, lymph vessels originate as microscopic spaces.

And finally converge into the great thoracic duct, which opens into the venous system. The aggregates of lymphatic tissue form the lymph glands or lymph nodes and lymphoid structures or lymph organs. A group of organs and tissues, which produce lymphocytes are collectively termed the lymphoid organs.

Lymphoid organs are subdivided into the primary lymphoid organs and the peripheral lymphoid organ. Primary lymphoid organs include the bone marrow and the thymus, which supply the peripheral lymphoid organs with mature lymphocytes already programmed to perform their functions. Peripheral lymphoid organs include the spleen, lymph nodes, tonsils, and the epithelium associated lymphoid tissue.

Bone marrow is the hollow space in bones, which is made up of tissues, fat, blood vessels, and blood cell precursor cells. The formation of new blood cells takes place in the bone marrow. The thymus lies in the upper part of the chest and secretes the hormone thymus in which has a regulatory effect on the peripheral lymphocytes.

The spleen is the largest of the lymphoid organ. Which lies in the left part of the abdominal cavity between the stomach and the diaphragm. It contains a large collection of lymphocytes and macrophages. The tonsils are a group of small rounded organs in the pharynx, which are also filled with lymphocytes and macrophages.

The lymph nodes are oval or bean shaped, aggregates of lymphatic. These vary considerably in size as small as the head of a pin to as large as a bean, and usually occur in chains of two to 12, although occasionally a node may exist alone. Each node has a slight depression on one side called the highli through which an artery and vein enter and leave.

Besides, there are several lymphatic vessels which carry lymph away from the node. The node is surrounded by a capsule of fibrous connective tissue, which also radiates through the lymph node substance. These fibrous radiations are called trabeculectomy, which divide the interior of the node into spaces called lymph sinuses, which are filled with masses of lymphoid tissue called limb follicles.

The follicular substance appears to be an area of interaction between the blood and the lymph. The lymphocytes are produced by the lymphoid organs. The undifferentiated lymphoid cells derived from fetal liver or bone marrow migrate to the thymus and are differentiated into B lymphocytes and T lymphocytes.

B lymphocytes or B cells mature in the bone marrow and are then carried by the blood to the peripheral lymphoid organ. In addition, other lymphocytes leave the bone marrow in an immature state. During fetal and early neonatal life, these cells are carried to the thymus where they mature to form T lymphocytes or T-cells, and are then carried to the peripheral lymphoid organs.

A third class of lymphocytes often termed natural killer T-cells or NK cells are also present in addition to the B and t-cell. Immunity or immune response refers to the resistance exerted by the organisms to invasive pathogens such as viruses, bacteria, fungi, and other parasites or their toxic products, as well as non microbial foreign matters.

Immunity or immune response can be divided into two main types, one innate immunity or non-specific immune response. And two acquired immunity or specific immune responses. Innate immunity is the natural immunity which a person receives from his or her genetic constitution does not arise from prior infection or vaccination.

These include the common protective reactions of the organism against the invasion of foreign substances or cells, such as surface barriers, biochemical factors, and cellular mechanism. Intact skin, mucus membranes, lysozymes and other physical barriers help prevent pathogens from infecting the body.

Pathogens generally cannot get past the skin and the inner lining of organs, such as the epithelial lining of the digestive tract. The inner walls of the respiratory airways are present with sticky mucus, which prevents airway infection. The lysozymes and other chemicals present in mucus tears, saliva and gastric fluid provide protection by destroying bacteria.

The urinary tract is prevented from infections by the urine's, low pH and flushing action. Interferons are a group of glycoproteins that are produced by every nucleated human cell in response to a wide range of stimuli, such as bacterial, viral, and parasitic infections or tumor cells. Interferons are designated alpha, beta, gamma, and Amiga on the basis of their association with the producer cells and function.

Interferons inhibit viral replication in the neighboring uninfected cells through specific receptors on the cells without interfering with their normal metabolic processes. Interferons also inhibits cell proliferation of certain tumors encouraging its use in cancer therapy. The cellular mechanisms of the immune system include cellular components involved in natural resistance, namely phytic cells.

Anti-inflammatory responses and natural killer cells or NK cells. Phagocytosis is a process whereby a single phagocytic cell, ingul objects such as non-functional cells, mutated cells, or invading infectious organisms. Inflammatory responses are the body's local response to infection or injury. The familiar manifestation of inflammation includes local redness, swelling, burning, sensation, and pain.

The key components in inflammation are phagocytes, neutrophils, monocytes, and macrophages. Neutrophils are abundant in the blood. These enter the tissues and fize pathogens in acute inflamm. Monocytes are a type of white blood cell made in the bone marrow, which enter the blood and migrate into the connective tissue where they differentiate into macrophages.

Macrophages secret, various substances which contribute to natural resistance, natural killer cells or NK cells, or small cytotoxic lymphocytes that play a major role in innate immunity. NK cells are a part of the first line of defense against cancer and infected cells. These cells are named as natural killers, as they do not require activation by specific antigens present on the cell, but are activated by cytokines released from other immune cells.

The acquired or specific immune responses include two broad categories, antibody mediated immune response, AMI or humeral immunity. And cell mediated immune response. CMMI antibody mediated immunity refers to the immune response initiated by antibodies released from B-cells. The B lymphocytes or B-cells on interaction with antigens, proliferate and differentiate into specialized cells called plasma cells and memory cells.

The plasma cells produce antibodies that bind to the antigen and destroy them. While the memory cells remain in the body for a longer duration and stimulate B-cells to produce antibodies when the body is again exposed to the same antigen, the cell mediated immune response involves the macrophages natural killer cells and kce helper T-cells, and cytotoxic T-cells.

This provides major defense against intracellular viruses and cancer. Macrophages and NK cells target cells infected with microorganisms such as bacteria, viruses, and certain fungi Helper T-cells, also known as CD four cells or CD four lymphocytes are white blood cells that carry CD four receptor on their surface.

CD four cells play an important role by stimulating other immune cells during an immune. T-cells with CD four receptors recognize antigens on the surface of a virus infected cell and secret lymphocy that stimulate B-cells and cytotoxic T-cells. Cytotoxic T-cells, also known as CD eight cells or killer T-cells have T-cell receptors TCRs on their surface that recognize an antigen peptide complexed with MHC class one smolecule.

These white blood cells thus help in destroying, infected and damaged cells. The human body's defense mechanisms consist of organs, tissues, cells, and their products. They're protected from pathogens and allergens. The organs, types of cells involved and the different types of immune pathways are depicted in these videos of virtual reality making, the understanding of these basic incidents of the human body quite simple.