LYMPHATIC SYSTEM HLTAP301A

Lymphatic System Closely connected to the circulatory system as it is mainly a network of capillaries and vessels Plays an important role in defending the body against disease

Lymphatic System Components Lymphatic capillaries Lymphatic vessels Lymphatic nodes Lymphatic ducts Lymph

Lymphatic system Body parts also containing lymphatic tissue Tonsils Thymus gland Peyer’s patches spleen

Lymphatic System Functions Defence Removal of damaged body tissues Destruction of cancerous cells

Lymphatic System Defence First line of defence Skin – injury allows bacteria to enter the body Mucous membrane – vaginal mucosa produces an acidic bacteria which prevents micro-organisms from entering the body Normal body flora – digestive system contains bacteria in mouth and large bowel Some body secretions – prevents entry of foreign invaders by liquid flow

Lymphatic System Second line of defence Phagocytic cells – their job is to engulf and destroy invaders Inflammatory response Natural killer cells – type of WBC, T cells Protective proteins – antibodies, B cells

How do they work? B cell tags invaders with antibodies so other immune system cells will know to destroy them Killer cell devours invaders or release toxic chemicals that kill invaders Cytotoxic T cell destroys infected body cells before the virus has a chance to multiply Macrophage devours invaders and launches the immune system attack Memory cell makes immune responses faster next time the invader returns Helper T cell coordinates the immune system attack by recruiting and activating other immune cells

White Blood Cells Neutrophils Make up about 70% of WBC Produced in bone marrow then released into the bloodstream Lifespan 6-8 hours They engulf and destroy foreign invaders During infectious illness their numbers increase-called neutrophila

White Blood cells 2. Lymphocytes About 20% of WBC Two types are Type B which produce antibodies Type T which destroy body cells affected by viruses

Lymphatic system Antibodies The first time the body is exposed to a specific invader an immunologic memory is triggered If the invader returns it does not cause disease because it is met with large amounts of the specific antibody Active immunisation occurs when dead or weakened virus is injected into the body. This tricks the immune system into making antibodies Passive immunisation is the injection of preformed antibodies into the body

Organs of the immune system Lymphatic tissue Made of a variety of cells belonging to the immune system An example is the tonsils that guard the entrance to the digestive tract Lymph nodes Structures found lying along lymphatic vessels They act as filters and trap foreign substances Lymphocytes within these nodes produce antibodies

Organs Of the Immune system Spleen Found in the upper left abdomen against upper left side of stomach Largest mass of lymphatic tissue in the body Contains various types of WBC which trap and destroy invaders Also produces antibodies Rich blood supply and is the main filtering unit of immune system Acts as a graveyard for worn out RBC

Organs of the Immune System Thymus Found in upper anterior chest cavity between sternum and pericardium Plays important role in development and maturation of immune system Once immune system is mature it no longer has a function

Lymph Flow Body cells are surrounded by tissue fluid that comes from the bloodstream Much of this fluid diffuses back into blood vessels and the excess filters into lymphatic capillaries and is called lymph Lymph is similar to plasma but is 95% water Lymphatic capillaries become larger until they empty into either the right lymphatic duct or the thoracic duct These ducts then empty into the large veins of the upper body

Lymphatic System

Disorders Allergic responses – for example asthma, dermatitis and anaphylaxis Autoimmune – person’s immune system produces antibodies against it’s own cells. Includes rheumatoid arthritis, diabetes mellitus Immunodeficiency diseases – compromised immune system. Example is AIDS