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Lymphatic system by yogesh patel GRYIP borawan

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The lymphatic system acts as a filter against microbes and other debris. It comprises lymph fluid, lymph corpuscles like lymphocytes, and lymphoid organs like lymph nodes and the spleen. Lymph nodes filter lymph and mount immune responses, while the spleen filters blood and produces immune cells. Together they defend the body against infection.

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6. Lymphatic system Lymph and lymphatic system, composition, function and its formation. Structure and functions of spleen and lymph node.

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Composition, function and formation of Lymph Lymph is a colourless fluid that circulates throughout the lymphatic system. The main role of the lymphatic system is to act as a filter against microbes, organic wastes, toxins and other debris. It carries lymphocytes throughout the body that fight against infections. Composition of Lymph The lymphatic system comprises lymph plasma, lymph corpuscles and lymphoid organs. The composition of lymph is described below: 1. Lymph Plasma Lymph is the interstitial fluid. It has similar mineral content as in plasma. It consists of less calcium, few blood proteins, less phosphorus, and high glucose concentration. Globulin proteins which are actual antibodies are found in lymph plasma. Other substances include organic and inorganic substances. The exchange of nutrients and gases between the blood and cells of tissues occurs through the lymph.

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2. Lymph Corpuscles These comprise leucocytes and amoeboid cells. It contains specialised lymphocytes that are involved in eliciting immune responses in the human body. 3. Lymphoid Organs The lymphatic system consists of numerous lymph nodes deep inside the body. These lymph nodes are connected to lymphatic vessels which circulate the lymph throughout the body. The lymph gets filtered at the lymph nodes. The spleen, tonsils, adenoids and thymus all form a part of the lymphatic system. The spleen is considered the largest lymphatic organ in the system, which is located under the ribcage, above the stomach, and exactly in the left upper quadrant of the abdomen. Other parts of the lymphatic system – tonsils, adenoids and thymus are located on either side of the throat and neck.

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Other Components of Lymph in Humans • Carbohydrates • Lymphocytes • Creatinine • Water – 94% • Urea • Chlorides • Enzymes • Proteins – Albumin, globulin, and fibrinogen • Non-protein nitrogenous substances.

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Lymphatic system by yogesh patel GRYIP borawan

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Function of Lymph: Lymph performs many important functions. A few major functions of lymph are mentioned below: Nutritive: It supplies nutrition and oxygen to those parts where blood cannot reach. Drainage: It drains away excess tissue fluid and the metabolites and in this way tries to maintain the volume and composition of tissue fluid constant. Transmission of Proteins: Lymph returns proteins to the blood from the tissue spaces. Absorption of Fats: Fats from the intestine are also absorbed through the lymphatics.

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Defensive: The lymphocytes and monocytes of lymph act as defensive cells of the body. The lymphatics also remove bacteria from tissues. • It keeps the body cells moist. • It transports oxygen, hormones and nutrients to different parts of the body and removes metabolic waste from the cells. • It transports antibodies and lymphocytes to the blood. • Maintaining the composition of tissue fluid and the volume of blood. • Absorption of fats from the small intestine occurs through lymphatic vessels. • Prevents invasion of microbes and foreign substances inside the lymph nodes.

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Formation of Lymph: lymph is formed from tissue fluid, anything that increases the amount of tissue fluid will increase the rate of lymph formation. Lymph formation depends upon physical factors. The following factors are responsible for lymph formation: 1. Capillary Pressure: If the capillary pressure is raised, the rate of lymph formation increases. This is seen in venous obstruction. [But after some time, the rate slows down due to increased accumulation of fluid in the tissue spaces and the consequent rise of hydrostatic pressure of the tissue fluid.]

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2. Permeability of the Capillary Wall: Under any condition, where the permeability of the capillary wall is increased, more tissue fluid will be formed and consequently more lymph. 3. Substances that Alter the Osmotic Pressure: Anything that reduces the colloidal osmotic pressure of blood will increase the formation of tissue fluid and lymph. Normal or hypotonic saline, when given intravenously, will dilute the plasma colloids and reduce the osmotic pressure. Moreover, blood pressure will be raised. Both these factors will favour formation of tissue fluid and lymph. Hypertonic solutions will exert the same effect in a better way.

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4. Increased Metabolic Activity of an Organ: Increased activity of a particular area increases the flow of lymph in the locality It is due to: • Formation of more metabolites which increase the osmotic pressure of the tissue fluid. • Local vasodilatation and increased capillary pressure and permeability.

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Spleen The spleen is a large, encapsulated, bean-shaped organ that is situated on the left side of the body below the diaphragm. The spleen contains T and B lymphocytes as well as many phagocytes and is a major component of the mononuclear phagocyte system. Although the structure resembles that of the large lymph nodes, the spleen differs from a lymph node in having no lymphatic drainage, and also in containing large numbers of red cells.

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Structure of Spleen • It is a dark purple-coloured organ, which lies in the left hypochondriae region of the abdomen, between the fundus of the stomach and the diaphragm. • It varies in size and weight during the lifetime of an individual but in an adult is usually about 12 cm long, 8cm broad and 3-4 cm thick weighing about 200gm. • The spleen has diaphragmatic and visceral surfaces. The diaphragmatic surface is in contact with the inner surface of the diaphragm. • The spleen has an outer coat of peritoneum which is firmly adherent to the internal fibro-elastic coat or splenic capsule that dips into the organ, forming trabeculae.

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The spleen has a spongy interior called splenic pulp. The splenic pulps are of two kinds: White Pulp: • It consists of periarteriolar sheaths of lymphatic tissue with enlargements called splenic lymphatic follicles containing rounded masses of lymphocytes. • These follicles are center of lymphocytes production called primary lymphoid follicles, composed mainly of follicular dendritic cells (FDC) and B cells. • They are visible to the naked eye in freshly cut surface of the spleen as whitish dots against the dark red background of red pulp. • The white pulp forms ‘islands’ within a meshwork of reticular fibers containing red blood cells, macrophages and plasma cells (red pulp).

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Red Pulp: • It consists of numerous sinusoids containing blood, separated by a network of perivascular tissue which is referred to as the splenic cords. • The splenic cords contain numerous microphages abd are the site of intense phagocytes activity. • They also contain numerous lymphocytes, which are derived from the white pulp.

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Lymphatic system by yogesh patel GRYIP borawan

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Lymphatic system by yogesh patel GRYIP borawan

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Functions of Spleen 1. The main immunological function of the spleen is to filter the blood by trapping bloodborne microbes and producing an immune response to them. It is particularly important for B cell responses to polysaccharide antigens. 2. The spleen is formed partly by lymphatic tissue which produces T lymphocytes and B lymphocytes. 3. Due to the presence of lymphoid reticulo-endothelial tissue, the spleen is involved in producing antibodies and antitoxin. 4. In the foetus, the spleen acts as an important haemopoitic organ. 5. It also removes damaged red blood cells and immune complexes. 6. It can act as an erythropoietic organ which acts as a reservoir of erythrocytes or a reservoir for blood. 7. Those individuals who have had their spleens removed (splenectomized) have a greater susceptibility to infection with encapsulated bacteria, and are at increased risk of severe malarial infections, which indicates its major importance in immunity.

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Lymph node Lymph nodes are small solid structures placed at varying points along the lymphatic system such as the groin, armpit and mesentery. • They contain both T and B lymphocytes as well as accessory cells and are primarily responsible for mounting immune responses against foreign antigens entering the tissues. • Lymph nodes are situated at strategic positions throughout the body and serve to filter the lymph.

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Structure of Lymph Nodes • They range in size from 2 to 10 mm, are spherical in shape and are encapsulated. • Lymph node is surrounded by a fibrous capsule which dips down into the node substance forming partition or trabeculae. • The node is made by reticular and lymphatic tissues containing mainly lymphocytes and macrophages. • Beneath the capsule is the subcapsular sinus, the cortex, a paracortical region and a medulla. • The cortex contains many follicles and on antigenic stimulation becomes enlarged with germinal centers.

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• The follicles are comprised mainly of B cells and follicular dendritic cells. • The paracortical (thymus-dependent) region contains large numbers of T cells interspersed with inter digitating cells. • Each lymph node has 4-5 afferent vessels that bring lymph to the node while only one efferent vessel draining lymph away from the node. • It also has a concave surface called the hilum where an artery enters, a vein and the efferent lymph vessel leave. • Depending upon the position, the lymph nodes may be superficial or deep lymph nodes. Groups of lymph nodes are present in the neck, collarbone, under the arms (armpit), and groin.

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Lymphatic system by yogesh patel GRYIP borawan

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Lymph Circulation in Lymph Nodes 1. Lymph arriving from the tissues or from a preceding lymph node in the chain, passes via the afferent lymphatics into the subcapsular sinus and then into the cortex, around the follicles, into the paracortical area and then into the medulla. 2. Lymph in the medullary sinuses then drains into efferent lymphatics and hence through larger lymphatic vessels back into the bloodstream.

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Functions of Lymph Nodes 1. The primary role of the lymph node is to filter the lymph and then produce an immune response against trapped microbes/antigens. 2. Filtering of the lymph helps in removal of particles not normally found in the serum. 3. The lymphoide tissues in the nodes break down materials which have been filtered off such as microorganisms, tumor cells and cells damaged by inflammation. 4. Lymphocyte develops from the reticular and lymphoid tissue in the nodes. 5. Antibodies and antitoxins are also formed by the cells of lymph nodes.

More Related Content

Lymphatic system by yogesh patel GRYIP borawan

  • 1. 6. Lymphatic system Lymph and lymphatic system, composition, function and its formation. Structure and functions of spleen and lymph node.
  • 2. Composition, function and formation of Lymph Lymph is a colourless fluid that circulates throughout the lymphatic system. The main role of the lymphatic system is to act as a filter against microbes, organic wastes, toxins and other debris. It carries lymphocytes throughout the body that fight against infections. Composition of Lymph The lymphatic system comprises lymph plasma, lymph corpuscles and lymphoid organs. The composition of lymph is described below: 1. Lymph Plasma Lymph is the interstitial fluid. It has similar mineral content as in plasma. It consists of less calcium, few blood proteins, less phosphorus, and high glucose concentration. Globulin proteins which are actual antibodies are found in lymph plasma. Other substances include organic and inorganic substances. The exchange of nutrients and gases between the blood and cells of tissues occurs through the lymph.
  • 3. 2. Lymph Corpuscles These comprise leucocytes and amoeboid cells. It contains specialised lymphocytes that are involved in eliciting immune responses in the human body. 3. Lymphoid Organs The lymphatic system consists of numerous lymph nodes deep inside the body. These lymph nodes are connected to lymphatic vessels which circulate the lymph throughout the body. The lymph gets filtered at the lymph nodes. The spleen, tonsils, adenoids and thymus all form a part of the lymphatic system. The spleen is considered the largest lymphatic organ in the system, which is located under the ribcage, above the stomach, and exactly in the left upper quadrant of the abdomen. Other parts of the lymphatic system – tonsils, adenoids and thymus are located on either side of the throat and neck.
  • 4. Other Components of Lymph in Humans • Carbohydrates • Lymphocytes • Creatinine • Water – 94% • Urea • Chlorides • Enzymes • Proteins – Albumin, globulin, and fibrinogen • Non-protein nitrogenous substances.
  • 6. Function of Lymph: Lymph performs many important functions. A few major functions of lymph are mentioned below: Nutritive: It supplies nutrition and oxygen to those parts where blood cannot reach. Drainage: It drains away excess tissue fluid and the metabolites and in this way tries to maintain the volume and composition of tissue fluid constant. Transmission of Proteins: Lymph returns proteins to the blood from the tissue spaces. Absorption of Fats: Fats from the intestine are also absorbed through the lymphatics.
  • 7. Defensive: The lymphocytes and monocytes of lymph act as defensive cells of the body. The lymphatics also remove bacteria from tissues. • It keeps the body cells moist. • It transports oxygen, hormones and nutrients to different parts of the body and removes metabolic waste from the cells. • It transports antibodies and lymphocytes to the blood. • Maintaining the composition of tissue fluid and the volume of blood. • Absorption of fats from the small intestine occurs through lymphatic vessels. • Prevents invasion of microbes and foreign substances inside the lymph nodes.
  • 8. Formation of Lymph: lymph is formed from tissue fluid, anything that increases the amount of tissue fluid will increase the rate of lymph formation. Lymph formation depends upon physical factors. The following factors are responsible for lymph formation: 1. Capillary Pressure: If the capillary pressure is raised, the rate of lymph formation increases. This is seen in venous obstruction. [But after some time, the rate slows down due to increased accumulation of fluid in the tissue spaces and the consequent rise of hydrostatic pressure of the tissue fluid.]
  • 9. 2. Permeability of the Capillary Wall: Under any condition, where the permeability of the capillary wall is increased, more tissue fluid will be formed and consequently more lymph. 3. Substances that Alter the Osmotic Pressure: Anything that reduces the colloidal osmotic pressure of blood will increase the formation of tissue fluid and lymph. Normal or hypotonic saline, when given intravenously, will dilute the plasma colloids and reduce the osmotic pressure. Moreover, blood pressure will be raised. Both these factors will favour formation of tissue fluid and lymph. Hypertonic solutions will exert the same effect in a better way.
  • 10. 4. Increased Metabolic Activity of an Organ: Increased activity of a particular area increases the flow of lymph in the locality It is due to: • Formation of more metabolites which increase the osmotic pressure of the tissue fluid. • Local vasodilatation and increased capillary pressure and permeability.
  • 11. Spleen The spleen is a large, encapsulated, bean-shaped organ that is situated on the left side of the body below the diaphragm. The spleen contains T and B lymphocytes as well as many phagocytes and is a major component of the mononuclear phagocyte system. Although the structure resembles that of the large lymph nodes, the spleen differs from a lymph node in having no lymphatic drainage, and also in containing large numbers of red cells.
  • 12. Structure of Spleen • It is a dark purple-coloured organ, which lies in the left hypochondriae region of the abdomen, between the fundus of the stomach and the diaphragm. • It varies in size and weight during the lifetime of an individual but in an adult is usually about 12 cm long, 8cm broad and 3-4 cm thick weighing about 200gm. • The spleen has diaphragmatic and visceral surfaces. The diaphragmatic surface is in contact with the inner surface of the diaphragm. • The spleen has an outer coat of peritoneum which is firmly adherent to the internal fibro-elastic coat or splenic capsule that dips into the organ, forming trabeculae.
  • 13. The spleen has a spongy interior called splenic pulp. The splenic pulps are of two kinds: White Pulp: • It consists of periarteriolar sheaths of lymphatic tissue with enlargements called splenic lymphatic follicles containing rounded masses of lymphocytes. • These follicles are center of lymphocytes production called primary lymphoid follicles, composed mainly of follicular dendritic cells (FDC) and B cells. • They are visible to the naked eye in freshly cut surface of the spleen as whitish dots against the dark red background of red pulp. • The white pulp forms ‘islands’ within a meshwork of reticular fibers containing red blood cells, macrophages and plasma cells (red pulp).
  • 14. Red Pulp: • It consists of numerous sinusoids containing blood, separated by a network of perivascular tissue which is referred to as the splenic cords. • The splenic cords contain numerous microphages abd are the site of intense phagocytes activity. • They also contain numerous lymphocytes, which are derived from the white pulp.
  • 17. Functions of Spleen 1. The main immunological function of the spleen is to filter the blood by trapping bloodborne microbes and producing an immune response to them. It is particularly important for B cell responses to polysaccharide antigens. 2. The spleen is formed partly by lymphatic tissue which produces T lymphocytes and B lymphocytes. 3. Due to the presence of lymphoid reticulo-endothelial tissue, the spleen is involved in producing antibodies and antitoxin. 4. In the foetus, the spleen acts as an important haemopoitic organ. 5. It also removes damaged red blood cells and immune complexes. 6. It can act as an erythropoietic organ which acts as a reservoir of erythrocytes or a reservoir for blood. 7. Those individuals who have had their spleens removed (splenectomized) have a greater susceptibility to infection with encapsulated bacteria, and are at increased risk of severe malarial infections, which indicates its major importance in immunity.
  • 18. Lymph node Lymph nodes are small solid structures placed at varying points along the lymphatic system such as the groin, armpit and mesentery. • They contain both T and B lymphocytes as well as accessory cells and are primarily responsible for mounting immune responses against foreign antigens entering the tissues. • Lymph nodes are situated at strategic positions throughout the body and serve to filter the lymph.
  • 19. Structure of Lymph Nodes • They range in size from 2 to 10 mm, are spherical in shape and are encapsulated. • Lymph node is surrounded by a fibrous capsule which dips down into the node substance forming partition or trabeculae. • The node is made by reticular and lymphatic tissues containing mainly lymphocytes and macrophages. • Beneath the capsule is the subcapsular sinus, the cortex, a paracortical region and a medulla. • The cortex contains many follicles and on antigenic stimulation becomes enlarged with germinal centers.
  • 20. • The follicles are comprised mainly of B cells and follicular dendritic cells. • The paracortical (thymus-dependent) region contains large numbers of T cells interspersed with inter digitating cells. • Each lymph node has 4-5 afferent vessels that bring lymph to the node while only one efferent vessel draining lymph away from the node. • It also has a concave surface called the hilum where an artery enters, a vein and the efferent lymph vessel leave. • Depending upon the position, the lymph nodes may be superficial or deep lymph nodes. Groups of lymph nodes are present in the neck, collarbone, under the arms (armpit), and groin.
  • 22. Lymph Circulation in Lymph Nodes 1. Lymph arriving from the tissues or from a preceding lymph node in the chain, passes via the afferent lymphatics into the subcapsular sinus and then into the cortex, around the follicles, into the paracortical area and then into the medulla. 2. Lymph in the medullary sinuses then drains into efferent lymphatics and hence through larger lymphatic vessels back into the bloodstream.
  • 23. Functions of Lymph Nodes 1. The primary role of the lymph node is to filter the lymph and then produce an immune response against trapped microbes/antigens. 2. Filtering of the lymph helps in removal of particles not normally found in the serum. 3. The lymphoide tissues in the nodes break down materials which have been filtered off such as microorganisms, tumor cells and cells damaged by inflammation. 4. Lymphocyte develops from the reticular and lymphoid tissue in the nodes. 5. Antibodies and antitoxins are also formed by the cells of lymph nodes.