Lymphatic Ducts Receive lymph from lymphatic trunks. Right lymphatic duct – Receives lymph from the right jugular, right subclavian, and right bronchomediastinal trunks – Empties into the right internal jugular vein Thoracic duct – Receives lymph from the left jugular, left subclavian, left bronchomediastinal, intestinal, and lumbar trunks – Empties into the left internal jugular vein
Lymphatic Vessels Lymphatic Trunks Lymphatic Ducts Bloodstream Where’s pressure high and where’s pressure low? What makes lymph flow?
Lymph Flow Lymph flow will be similar to… 3 main factors promote lymph flow: – Skeletal muscle pump – Respiratory pump – Lymphatic smooth muscle
1. How does elevating an injured limb affect lymph flow? 2. How would exercise affect lymph flow? 3. How could massage affect lymph flow? 4. In some surgeries for breast cancer, the lymph nodes along thearm are removed in order to assess the spread of the disease. What would be a result of this?
What happens when lymph cannot flow? What could prevent lymph from flowing? Filaria
Lymphocytes – T lymphocytes Kill virus-infected and cancerous cells Coordinate/control immune response – B lymphocytes Become plasma cells which secrete antibodies Phagocytes – Eat and kill and activate the rest of the immune system Dendritic cells – Activate the immune system Reticular cells – Make reticular fibers that support lymphatic tissues and organs Lymphoid Cells
Reticular connective tissue forms the framework of most lymphoid tissues and organs.
Lymphoid Tissue Aggregations of lymphoid cells Storage/proliferation site for lymphoid cells Surveillance site 2 main types – Diffuse lymphatic tissue – Lymphoid follicles
Diffuse Lymphatic Tissue What does “diffuse” mean? Found in lymph nodes and spleen. Especially prominent in the mucous membranes lining the digestive, respiratory, urinary, and reproductive tracts. – Hence the term MALT.
Mucosa Associated Lymphatic Tissue Where are the mucosae? Why is lymphoid tissue needed there? 2 main types: – GALT – BALT
Lymphoid Follicles A.k.a. lymphoid nodules Solid, packed spherical clusters of lymphoid cells and reticular tissues Often found as parts of larger lymphoid organs (e.g., lymph nodes) Found in the mucosae Large number in the distal ileum and appendix
Lymphoid follicle in the stomach
Peyer’s Patches – Aggregates of lymphoid follicles found in the distal small intestine. Why there?
Appendix – Blind outpocketing of the cecum. – Contains aggregates of follicles.
Lymphoid Organs Surrounded by a capsule of dense connective tissue. Lymph nodes Tonsils, thymus, spleen
Lymph Nodes Filter lymph Clustered along lymphatic vessels Large superficial clusters in inguinal, axillary, and cervical regions.
Lymph Nodes Receive lymph from an afferent lymphatic vessel Drain lymph into an efferent lymphatic vessel Surrounded by dense CT capsule – Inward extensions (trabeculae) divide it into compartments Reticular fibers support the resident macrophages and lymphocytes Divided into a cortex and a medulla
Flow Through the Node Afferent lymphatic vessel Subcapsular sinus Cortical sinus Medullary sinus Efferent lymphatic vessel What happens to the lymph during this journey? What does the lymph flow past?
Spleen Largest lymphoid organ Sits just below the diaphragm, kind of behind the stomach and above the kidney and colon. What protects it?
Spleen Major function is blood cleansing – Removal of aged, broken, or malformed RBCs. Who does this? – Removal and destruction of pathogens and foreign matter. Who does this?
Spleen Surrounded by a CT capsule w/ inward extending trabeculae Internal framework is provide by reticular fibers.
Spleen Splenic arterioles are surrounded by sheathes of lymphocytes. – This is known as the white pulp of the spleen. – What will happen here? The arterioles terminate in splenic capillaries – which are twisty, sinusoidal, and incomplete. – The capillaries and the surrounding splenic tissue is referred to as the red pulp of the spleen. – Macrophages line the capillary surface. – Why?
Other Spleen Functions Storage of RBC breakdown products Platelet storage Fetal RBC production
Which would contain more damaged RBCs and more pathogens – the splenic artery or the splenic vein?
Thymus Largest and most active in fetus and infancy Involved in T lymphocyte maturation and selection – Also, the removal of those T cells that attack self tissue Growth ceases during adolescence No direct fighting.
Tonsils Form a ring of lymphatic tissue at the entrance to the pharynx. 3 main types: – Palatine – Pharyngeal – Lingual
Palatine – located laterally in the posterior oral cavity. Largest and most often infected.
Pharyngeal – located in the posterior nasopharynx. A.k.a adenoids.
Lingual – located at the base of the tongue.
Not fully encapsulated. Why not? Contain crypts. What’s their advantage? What’s their disadvantage?