Lecture 23: Lymphatic System Flashcards
What is lymph?
Thin fluid that resembles plasma but has lesser protein
What is chyle?
Lymph that arises in GI tract containing fats and dissolved lipids
How much lymph is produced each day?
3-5 liters
What are the 4 lymphatic vessels?
Capillaries, trunks, ducts, veins
What are the 5 structures that lymph flows through from the tissue to the vein?
Lymphatic capillary Lymphatic vessel Lymphatic node Lymphatic trunk Lymphatic duct
What are 2 similarities between lymphatic capillaries and veins?
Low pressure
Valves present
What is the difference between veins and lymphatic capillaries?
No cells in lymphatic vessels but cells present in veins
What is the cisterna chyli?
Large container of chyle from GI tract
What does the lymph from upper right quadrant drain into?
Right lymphatic duct into right subclavian vein
Where does the lymph from the rest of the body flow into?
Thoracic duct into left subclavian vein
What are the 3 most important lymph nodes?
Neck (cervical)
Groin (inguinal)
Armpit (axillae)
What is the structure of lymphatic vessels in lymph nodes?
Multiple afferent lymphatic vessels that enter via convex surface and single efferent lymphatic vessel that leaves via concave hillbilly
What is the structure of the lymph nodes?
Multiple nodules that contain immune cells (macrophages, dendritic, B and T cells, plasma cells)
What is the main connective tissue fibre in lymph nodes?
Reticular
Where are follicular dendritic cells located?
Germinal centers of lymph node
What are the 2 functions of follicular dendritic cells?
Antigen antibody complexes adhere to dendritic processes to be presented to T cells
Cause proliferation of B cells, in particular memory B cells
How do T and B cells work together?
B cells finds antigen and presents it to T cell, which activates it to be able to produce plasma and memory cells. Plasma cells then produce antibodies that attach to the antigen, then macrophages eats them.
What is the structure of blood vessels in lymph nodes?
Feeding artery and draining vein that enter and leave via the hilum
What is lymphadenopathy?
Enlarged lymph nodes
What are the causes of lymphadenopathy?
- During infections, germinal centers fill with increasing numbers of lymphocytes causing lymph nodes to swell
- Cancer metastasize to lymph nodes
- Lymphoma
What are 6 lymphatic organs?
Thymus Bone marrow Spleen Tonsils Appendix Payer’s patches
Where is the thymus located?
Superior mediastinum
What is the structure of the thymus?
Similar to lymph node (cortex medulla and germinal centre) but no hilum
What is the function of the thymus?
Thymic cell education - maturation of bone marrow derived stem cells into immunocompetent T cells
What is myasthenia crisis?
Inability to swallow due to weakened muscles
Where is the spleen?
Inferior to diaphragm, posterior to stomach
What is the structure of the spleen?
White pulp made of lymphocytes and red pulp made of erythrocytes
What are the 2 types of function of spleen?
Immune and haemopoietic
What are 4 immune functions of the spleen?
- Antigen presentation by APCs
- Activation and proliferation of B and T lymphocytes
- Production of antibodies
- Removal of macro molecular antigen from blood
What are the 3 haemopoietic functions of spleen?
Removal and destruction of old, damaged and abnormal erythrocytes and platelets
Retrieval of iron from erythrocyte haemoglobin
Erythrocyte storage
What is a splenectomy?
Removal of spleen
What does splenectomy increase the risk of?
Infection by encapsulated bacteria and malaria
What is splenomegaly?
Enlargement due to localized infection or systemic infection
Where are 2 locations of the tonsils?
Oreo pharynx and nasopharynx
What are the 3 tonsils?
Pharyngeal tonsil
Palatine tonsil
Lingual tonsil
What is the structure of tonsils?
Nodules that reside inferior to surface invaginations
What are the 3 functions of tonsils?
Prevent pathogen ingress through oral and nasal routes
Prevent pathogen ingress through aural route
Crypts increase surface area
What kind of specialized cells does the surface epithelia of the tonsil have?
Micro fold cells that present antigen to underlying immune cells
Where is the vermiform appendix located?
Inferior to and attached to caecum
What is the structure of the vermiform appendix?
Nodules reside inferior to surface invaginations and many M fold cells in epithelial surface
What are the 3 functions of vermiform appendix?
Prevent pathogen ingress through GI routes
Prevent pathogen ingress arriving from ileum
Crypts increase surface area
Where are Payer’s Patches located?
Inferior to and attached to side of ileum
What is the structure of Payer’s patches?
Nodules reside inferior to surface domes and many M fold cells in epithelial surface
What is the function of Payer’s patches?
Prevent pathogen ingress through digestion
What are the 4 functions of the lymphatic system?
Fluid balance
Transport of fat and fat soluble vitamins
Defense against invading pathogens and disease
Storage of and destruction of aged erythrocytes (spleen)
What are sentinel lymph nodes?
First node to receive lymph from area of a primary tumor
What are 2 main types of lymphoedema?
Primary and secondary
What is primary lymphodema?
Inherited diseases
What are 3 examples of primary lymphoedema diseases?
Congenital (Milroy’s disease)
Praecox (Meige’s disease)- 2-35 years
Tarda (after 35)
What causes Milroy’s disease?
Mutated FLT4 gene leading to small or missing endothelial cells in vessel wall
What are 5 causes of secondary lymphoedema?
Neoplasia - inflamed pelvic masses infiltrate lymph node
Surgery - node involvement
Radiotherapy - nodal fibrosis
Autoimmune disease - rheumatoid arthritis or eczema
Infections - cellulitis (obstruction of vessel), filariasis (parasitic worm)
What are the treatments of lymphoedema?
Lympha Press System
