Table of Contents
Haematopoesis
Haematopoesis is the process by which all blood cells are produced. It occurs primarily in the bone marrow and involves the differentiation of hematopoietic stem cells (HSCs) into types of blood cells, including red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (trombocytes). This process is crucial for maintaining the body's immune system, oxygen transport, and clotting functions.
The process of hematopoiesis can be divided into several stages —
- Hematopoietic stem cells (HSCs) : These multipotent stem cells have the ability to self - renew and differentiate into all types of blood cells.
- Lineage Commitment: HSCs differentiate into either myeloid or Lymphoid progenitor cells. Myeloid progenitors give rise to erythrocytes, platelets, and several types of white blood cells (e.g., neutrophils, monocytes, eosinophils, and basophils). Lymphoid progenitors differentiate into lymphocytes B cells, T cells and natural killer cells.
- Precursor cells (Blasts) : Progenitor cells further differentiate into precursor cells or blasts, which are committed to forming specific types of blood cells.
- Mature blood cells: Blasts undergo further maturation and differentiation to become fully functional blood cells that are released into the bloodstream.
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Cells of immune system
The immune system has many types of cells that work together to protect the body from pathogens and other threats.
- White blood cells: Help fight against like bacteria, viruses, and toxins that can make yow sick. A weak immune system means there aren't enough white blood cells in the bloodstream.
- T cells: A subset of lymphocytes that help fight infections. In some cases, T cells can misidentify the body's own cells as foreign, and attack them, which can lead to conditions like Psoriasis.
- Natural killer cells: Part of the innate immune system, which is the body's first line of defense against treats.
- Phagocytes: Also part of the innate immune system, phagocytes activates the adaptive immune system by presenting antigens from pathogens to adaptive immunity cells.
- Dendritic cells: Antigen - Presenting cells that act as a link between the innate and adaptive immune systems. They can also help maintain immunologic tolerance.
- Immunoglobulins : Antibodies produced by the immune system that help defend against pathogens. They can be found in blood and saliva, where they can interfere with bacteria or inhibit their metabolism.
- Macrophages: A type of white blood cells that phagocytose foreign antigens like bacteria and present them to other immune cells for destruction.
- Basophils: Part of the innate immune system, basophils are responsible for inflamatory reactions during an immune response. They make up only 0.1 -1% of the circulating white blood cell population.
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Organs of Immune system
The immune system is a complex network of organs, tissues, and cells that work together to defend the body against infections and diseases. The thymus and bone marrow are important primary Lymphoid organs. Secondary Lymphoid tissues like the spleen, lymph arteries, tonsils, lymph nodes, skin, adenoids, and liver are all important parts of the immune system.
Primary Lymphoid Organs:
The primary sites of lymphocytes development, or lymphopoiesis, are known as primary lymphoid organs (PLO). Lymphocytes develop from lymphoid stem cells, multiply, and mature into useful cells Known as immuno - competent cells. B - cell maturation occurs in the bone marrow of animals, whereas T-cell maturation occurs in the thymus.
- Thymus : This tiny organs, located in the upper chest below breast bone, helps to mature a particular type of white blood cell. The particular task of this cell is to recognise and memorise an intruder so that a counter - attack can be easily mounted the next time this intruder attacks.
- Bone marrow: Red Blood cells, plasma cells, several types of white blood cells, and other immune cells are all produced from stem cells found in the spongy interior of the bones. Everyday, the bone marrow produces billions of new blood cells and releases them into the blood.
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Secondary Lymphoid organs:
In addition to the primary Lymphoid organs, there are a few other lymphoid organs known as secondary Lymphoid organs. The spleen and lymph nodes are the two most significant and well - organised secondary Lymphoid organs.
- Lymphoid nodes: The network of lymphatic channels (also known as lymphatic vessels) and lymph nodes are connected by lymphatic nodes. Immune cells found in lymph nodes examine foreign pathogens introduced into the body. The tiny glands filter and kill them to prevent germs from spreading to other body areas. They are a component of the lymphatic system in our body. The individual lymphocytes (white blood cells) are then activated, replicated,and send to combat that specific invader. Numerous lymph nodes can be found throughout the body, especially in the grain, armpits, and neck.
- Spleen: The secondary Lymphoid organs, the spleen, is situated high in the left abdominal area. Spleen are designed to filter blood, capture blood - bone antigens, and react to systemic infections.
The primary functions of the spleen are:
- Production of immune cells to fight antigens
- Removal of particulate matter and aged blood cells (red blood cells),
- Production of blood cells during foetal life.
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FAQs
What is the immune system?
The immune system is a network of cells, tissues, and organs that work together to defend the body against harmful pathogens like bacteria, viruses, and other foreign invaders.
What are the main components of the immune system?
The main components include immune cells (like white blood cells), tissues, and organs (primary and secondary lymphoid organs).
What is haematopoiesis?
Haematopoiesis is the process by which all blood cells (including immune cells) are formed from hematopoietic stem cells in the bone marrow.
What are the primary lymphoid organs?
The primary lymphoid organs are the bone marrow and the thymus. These organs are where immune cells are generated and mature.
