Lymphatic System 2004 Refer to chapter 14 in your text for additional help

Organs of Lymphatic System  Lymph vessels  Lymph nodes  Thymus  Tonsils  Spleen

Lymph  Specialized fluid formed in tissue spaces  Formed from blood plasma - or - interstitial fluid  Re-enters “circulation” via lymphatic capillaries

Lymph Vessels  Transports lymph back to circulatory system  Capillaries made of simple squamos epithelium = endothelium What is the importance of this?

Lymphatic Capillaries → Lymphatic Venules /veins → ↓ Terminal vessels: Right lymphatic duct -OR- Thoracic duct ← Circulatory veins Lymph Transport

Lymphatic Vessels Definitions  Rt. Lymphatic duct & thoracic duct  Cisterna chyli  Lacteals

Lymph Nodes  Located in clusters along pathway of lymphatic vessels  Range in size from pinhead to lima bean  Most grouped in specific clusters  Functions in defense and white blood cell formation

Lymph Nodes Locale  Clinically important lymph nodes Submandibular Axillary Inguinal Popliteal

Lymph Node Defense  4 afferent lymph vessels carry lymph to nodes  Nodes filter particles  Send back to circulatory system via 1 efferent lymph vessel

Thymus  Small lymphatic organ located in mediastinum  Source of lymphocytes before birth  Helps in maturation of lymphocytes (T-lymphocytes)  Cells made under control of hormone thymosin

Tonsils  Clusters of lymphatic tissue located in mucous membranes of mouth and throat  First line of defense from exterior environment  3 separate clusters: Palantine Pharyngeal Lingual

Tonsils continued

Spleen  Largest lymphatic organ  Located in upper left quadrant  Salvages iron and hemoglobin  Acts as blood reservoir  Filters blood Bacteria Foreign substances Old RBC’s

Spleen Location

Function of lymphatic system  Aka immune system  Made of molecules and cells  Provides protection from: Disease causing microorganisms Foreign tissue cells Malignant cells

Nonspecific immunity  Mechanisms that attack any irritant that threatens internal environment Skin Mucous membranes Tears

Inflammatory response  Part of nonspecific immunity  Involves phagocytic WBC’s entering affected area via: Increased blood flow Vascular permeability

Specific Immunity  Very specific protective mechanism against certain bacteria or toxins  Involves memory and recognition skills  Inborn or acquired immunity Natural immunity (passive or active)  Artificial immunity Active or passive