UNIT 5- Lymphatic System

What is Interstitial Fluid? As blood travels through capillaries, the blood is squeezed and fluid from the blood is forced out into the spaces between nearby cells – this fluid is known as interstitial fluid (composition is different from the blood).

What is Lymph? Some interstitial fluid is immediately reabsorbed back into the blood, but some remains, which then moves into (by osmosis) nearby lymphatic capillaries, [LYMPH]which is the beginning of the lymphatic pathway. Primary functions of lymph. return the proteins to the bloodstream that have leaked out of the blood capillaries transport bacteria /foreign particles to the lymph nodes.

Explain how the Lymphatic system is related to the Cardiovascular system. Network of capillaries /vessels that assist in circulating fluids Vessels have valves Drain excess fluid from interstitial spaces Filter and return excess fluid to the blood stream

Similar to Blood Capillaries Similar to Veins and have Valves Filter Lymph Located in trunk of body Right Lymphatic and Thoracic Under each clavicle

What are Collecting Ducts and where are they located? Right Lymphatic Duct – drains lymph from the right half of the upper body Thoracic Duct – drains lymph from the left half of the upper body and the entire lower body  

What is the importance of the Lymph node/gland? Located along lymphatic pathways Have lymphatic vessels leading in and out of them Only lymphoid structures that filter lymph Produce lymphocytes (most are produced in the bone marrow) Contain lymphocytes and macrophages to help in cleaning lymphatic fluid

Name 2 Major Lymphatic Organs and their functions. THYMUS GLAND in the mediastinum (superior to the heart) shrinks with age contains lymphocytes (produced in the bone marrow), then travel to the Thymus, where they remain as they mature – known as T- lymphocytes/ T- cells SPLEEN upper left abdominal cavity largest of the lymphatic organs contain lymphocytes (fight off viral attacks) and macrophages (fight bacteria, engulf damaged tissue) filters the blood of old, fragile RBC (RBC graveyard)

Tonsils: considered a lymph gland and contain lymphocytes

WBC aka Leukocytes Can leave the bloodstream (diapedesis)to fight infection Engulf damaged tissue [phagocytosis] Produce pus- indication of fighting infection Produce antibodies to fight foreign invaders Neutrophils (60%) – 1st to arrive at infection site Lymphocytes (30%) – Two varieties (T-cells and B-cells) Monocytes (8%) – Become macrophages and engulf bacteria, dead cells, and damaged tissue (phagocytosis) Eosinophils (2%) – Controls allergic reactions Basophils (0%) – Release histamine at site of damaged tissue (inflammation), and heparin (inhibits clotting)

Difference between B and T Lymphocytes B CELLS: Produced and mature in Bone Marrow Located in lymph nodes, spleen, tonsils Plasma cell-type of B cell that is an antibody factory to fight invaders [antigens-cause immune reactions] T CELLS: Produced in Bone Marrow and mature in THYMUS gland Located in lymph nodes, spleen, tonsils 3 Special T Cells: Helper T Cytotoxic T Memory T

3 Special T cells Helper T- assist B cells in producing antibodies Cytotoxic T- attack cancer/virally infected cells Memory T- produced due to exposure to an antigen but are used for future exposure to same antigen Vaccines/Immunizations= weak/dead virus stimulate Memory T cells preventing future infection

2 Types of Defense 1) Innate (Non-Specific) Species Resistance Skin Chemical – Fever Infection – Pus – WBC, Bacteria, Damaged Tissue - Redness – d/t vasodilation