Immune system organs university heal.pptx

Immune systems organs

1. GROUP 5 Presents IMMUNE SYSTEM ORGANS Presented by; Sharif: Bone marrows Siraj : Thymus Edumwe : Lymphatic system Hilal : Spleen Jonathan: Tonsils and skin

2. IMMUNE SYSTEM ORGANS Immune system organs are specialized structures where immune cell are produced, matured and activated 1. Primary Lymphoid Organs These are responsible for the production and maturation of immune cells Examples include: Bone marrows Thymus

3. BONES MARROW It is a semi-solid, spongy tissue inside the bones. Contains hematopoietic stem cells that develop into blood cells, stromal cells and sinusoidal blood vessels TYPES OF BONE MARROWS Red marrow. Essential in the production of blood cells Yellow marrow. It has fats and can also store energy

4. FUNCTIONS OF THE BONE MARROW Produces hematopoietic stem cells. These specialize into all types of blood cells It is a primary lymphoid organ since B lymphocytes and T lymphocytes start developing from It stores memory cells hence important during immune responses

5. THYMUS It is found behind the breast bone It functions most actively in young children and adolescents In adults, it shirks and it is replaced by fats It has two lobes with the outer cortex densely packed with T lymphoblasts and epithelial cells. The inner medulla has epithelial cells and specialized Hassali’s corpuscles

6. Thymosin This is a hormone secreted by the tjymus gland that is important in the development and functioning of the immune system. Main Roles of Thymosin : Maturation of T-lymphocytes (T cells); Thymosin stimulates immature T cells to mature and become functional in the thymus . These T cells are essential for cell-mediated immunity — the body’s defense against viruses, cancer cells, and pathogens . Regulation of immune response; Thymosin helps control the balance and activity of different immune cells, ensuring the immune system responds properly without overreacting . Promotion of immune competence; It enables T cells to recognize and distinguish between the body’s own cells and foreign invaders (self vs non-self recognition ). Tissue repair and regeneration; Some forms of thymosin , like thymosin β4, aid in wound healing, cell migration, and tissue repair.

7. FUNCTIONS OF THE THYMUS It is a site for maturation of T cells which fight infection and coordinate the immune responses Produces hormones like thymulin , thymosin which help in the differentiation and activation of T cells Teaches T cells to distinguish between body cells and foreign invaders

8. SECONDARY LYMPHOID ORGANS Lymphatic system Spleen Tonsils LYMPHATIC SYSTEM 1. Lymph nodes ; These are small bean shaped organs that that filter lymph. They contain immune cells that destroy pathogens including B cells and T cells. They are found in clusters in the neck, armpits, groin, and the abdomen.

9. Lymphatic system 2. Lymphatic vessels ; These are thin tubes that carry lymph from lymph capillaries which are concerned with absorption of interstitial fluid from tissues through out the body. They work similarly to veins with valves that prevent backflow. The vessels are lined by endothelial cells and have a thin layer of muscle that binds them to the surrounding tissue.

10. LYMPHATIC SYSTEM 3. Lymph ; This is a clear, colorless fluid similar to plasma that contains white blood cells that fight infections. It also collects foreign materials from tissues. Formation of lymph . Transduction: Lymph is primarily formed due to plasma from blood capillaries leaking into the surrounding tissue spaces creating interstitial fluid. This is due to the hydrostatic pressure in the capillaries being higher than that of the surrounding tissues

11. Formation of lymph and movement

12. ILLUSTRATION OF THE LYMPHATIC SYATEM

13. Functions of the lymph nodes Filter and remove foreign particles like bacteria from lymph before it returns to blood Produce and store lymphocytes When the B cells in lymph nodes are activated, they develop into plasma cells which produce antibodies They also ensure that only clean lymph flows back into blood steam via lymphatic vessels In lymph nodes is where lymphocytes became activated when they detect antigens Monitor the composition of lymph and signal the immune system

14. Differences between lymphadenopathy and lymphadenitis . Lymphadenopathy Lymphadenitis Enlargement or abnormality of lymph nodes due to any cause (infection, malignancy, immune reaction, etc.). Inflammation of the lymph nodes, usually caused by infection Can result from infections, autoimmune diseases, cancers (like lymphoma or metastasis), or drug reactions. Usually due to a local or systemic infection (bacterial, viral, or fungal). May be non-inflammatory (e.g., cancer, immune reaction). Always inflammatory — involves infection and immune cell activity. Nodes may be enlarged, firm, rubbery, or hard; usually not painful unless acutely infected. Nodes are tender, painful, warm, and may be associated with redness and fever Depends on the underlying cause (e.g., hyperplasia, neoplasia, infiltration). Shows infiltration by inflammatory cells (neutrophils, macrophages) and sometimes pus formation May persist depending on cause; requires identifying underlying condition. Usually resolves with treatment of infection (antibiotics or drainage if abscess forms).

15. SPLEEN It is located at the left side of the body It’s main functional components are the white pulp, a lymphoid tissue responsible for the immune responsible and the red pulp, a vascular tissue that filters blood, stores cells and breaks down old ed blood cells

16. Functions of the spleen It filters blood by removing old and damaged red blood cells Stores extra blood which is released into circulation during low blood pressure Prevents infections by filtering pathogens from blood The spleen is responsible for red blood cells production for the fetus Recycles iron and globin after the breakdown of old red blood cells

17. Tonsil These are located in the entrance to the respiratory and digestive tracts Tonsils are lymphoid tissues with a specialized lining having crypts that increase surface area for trapping pathogens Also have immune cells like lymphocytes, dendritic cells and macrophages

18. The diagram illustrates tonsils

19. Functions of tonsils Provide first line defense by trapping pathogens and initiating an immune response Contain immune cells that detect and neutralize germs Produce antibodies which defend the body against germs Filters small particles from inhaled air

20. OTHER IMMUNE SYSTEM ORGANS Skin Mucus membranes Lymphatic vessels

21. Skin Functions of the skin as an immune system organ Acts as a barrier against germs, chemicals, heat, light and mechanical injuries It provides innate and adaptive immune mechanisms that defend the body against pathogens It has Langerhans cells that process antigens and initiate immune responses

22. CONT: The skin hosts T cells and macrophages that contributes to the immune surveillance These cells on he skin also maintain a balance between inflammatory and anti- inflamatory processes The skin produces melanin to protect the body against UV radiations

23. Mucus membranes Mucus membranes are special linings that cover the internal surfaces of body passages which open to the outside such as the respiratory tract, digestive tract, urinary tract, and reproductive tract. These membranes are a first line of defense in the immune system . 1. Physical barrier; The epithelial cells of mucous membranes form tight junctions that prevent the entry of pathogens . The mucus they secrete traps dust, bacteria, and viruses before these can invade deeper tissues. 2 . Chemical defense; Mucus contains antimicrobial substances like : Lysozyme , which breaks bacterial cell walls, Lactoferrin , which binds iron and prevents bacterial growth and Defensins , which kill microbes directly. 3 . Immune cells; The mucous membranes house immune cells such as macrophages, dendritic cells, and lymphocytes that detect and respond to invaders. They are organized in structures called Mucosa-Associated Lymphoid Tissue, which includes : Tonsils (in the throat ), Peyer’s patches (in the small intestine ), Appendix and Bronchial-associated lymphoid tissue. 4 . Secretory antibodies (IgA ); Mucous membranes produce immunoglobulin A ( IgA) which is a key antibody that binds to pathogens and prevents them from attaching to mucosal surfaces. This provides localized immunity in areas like the gut, lungs, and nasal passages. 5. Ciliary action; In the respiratory tract, cilia on mucosal cells move trapped particles and microbes out of the airways a process called the mucociliary escalator.

24. The Peyer’s Patches Peyer’s patches are aggregated lymphoid nodules that play an important role in the body’s immune defense, especially in monitoring intestinal bacteria and preventing the growth of harmful pathogens in the gut. Location : Found in the mucosa and submucosa of the ileum . More numerous and larger toward the distal end of the small intestine. Structure : Each patch contains clusters of B and T lymphocytes . Covered by a special epithelium containing M cells ( microfold cells) that capture antigens from the gut and deliver them to immune cells. Functions: 1. Immune surveillance: Detects and responds to antigens (foreign particles) from food and microbes in the intestine . 2.Lymphocyte activation: Helps generate immune responses by activating B and T cells . 3.Production of antibodies: Especially IgA, which helps neutralize pathogens in the gut . 4.Maintains gut flora balance: Helps the immune system tolerate beneficial gut bacteria while reacting to harmful ones.

25. Functions of the mucus membrane Traps bacteria, dirt, and viruses since it is sticky Mucus in the mucus membrane contains antibacterial substances and enzymes that destroy pathogens It has lymphosites and dendritic cells that are immune cells Contains antibodies that neutralizes pathogens