**A&P 2 Unit 20 (Lab) [Lymphatic System] Flashcards
Functions of the Lymphatic System
- Transports excess interstitial fluid to blood
- Assists in dietary fat absorption
- Activation of the immune system
Structures of the Lymphatic System
- Lymphatic Vessels (“lymphatics”)
- Transport the fluid lymph
- Lymphoid tissues and organs
- Classified as: Primary or Secondary
- Abundant lymphocytes
Lymphatics
- Lymphatic capillaries collect interstitial fluid
- Fluid is now called lymph
- Lymph flows inside lymphatic vessels
- Right lymphatic duct and thoracic duct (left)
- Drain into right and left subclavian veins
Absorption of Dietary Facts
- Occurs along small intestine
- Fatty acids are usually too large to enter blood capillaries
- Enter lacteals (lymphatic capillaries)
Lymphocytes
- • Most abundant cell in the lymphatic system
- Types:
- B cells
- T cells
- NK cells
Development & Maturation of Lymphocytes
- All lymphocytes develop in the red bone marrow
- To “mature”= become immunocompetent
- B cells and NK cells mature in red bone marrow
- T cells migrate to thymus gland to mature
After Maturation of Lymphocytes
- Immunocompetent lymphocytes
- Re-enter bloodstream, then travel to red bone marrow and other lymphoid tissues
- Ready to respond
Classification of Lymphoid Tissue
- Primary vs. Secondary
- Encapsulated vs. Unencapsulated
Primary Lymphatic Tissue
- Where lymphocytes develop and mature
- Red bone marrow
- Thymus
Secondary Lymphatic Tissue
- Where lymphocytes may become activated in an immune response
- Lymph Nodes
- Tonsils
- Spleen
Encapsulated
- Have distinct fibrous covering
- Lymph Nodes
- Spleen
- Thymus
Unencapsulated
- Unencapsulated (no distinct covering)
- Mucosal-associated lymphoid tissue (MALT)
- Along digestive, respiratory, urinary tracts
- Includes:
- Tonsils
- Appendix
- Peyer’s Patches
Lymph Nodes
- Encapsulated
- Little organs
- Contain B cells, T cells, Macrophages
- Lymph enters through afferent vessels
- Lymph node “filters” lymph
- Lymph exits through efferent vessels
Spleen
- Largest lymphatic organ
- Left upper quadrant
- Filters blood (and stores platelets)
- White pulp: Immune responses (lymphocytes, phagocytes)
- Red pulp: Destroys old RBCs (macrophages)
- Thin capsule can easily rupture –> life threatening emergency (bleeding)
- B cell proliferation
B Cells
- Plasma Cells
- Produce & secrete antbodies
T Cells
- Cytotoxic T Cells
- Helper T Cells
- Suppressor T Cells
Cytotoxic T Cells
Attack foreign cells or body cells infected by viruses.
Helper T Cells
Stimulate activation & function of T & B Cells
Suppressor T Cells
Inhibit activation & function of T & B Cells
Lymphatic Valves
- Prevent back flow
- Promotes one-way flow
- Lymph moves slowly
Threee Types of Tonsils
- Pharyngeal
- Palatine
- Lingual
Metastasis
The development of secondary malignant growths at a distance from a primary site of cancer.
NK Cells
Control several types of tumors and microbial infections by limiting their spread and subsequent tissue damage.
Thymus
Site of T cell maturation
