Lymphatic System Flashcards
Describe the organisation of the lymphatic system
Lymph - lymphatic vessels - lymphoid tissues/organs - cells within tissues and organs
Describe lymph and how much is produced each day
Serum like, thin fluid (ph7.4)
3-5 litres and then recycled
What is chyle
Lymph from GI tract
Contains chylomicrons (fat)
And fat soluble vitamins
Vessel ordering in lymphatic system
Capillary, vessel, node, trunk, duct
Structure of lymphatic vessel
Capillaries Blind ended No basement membrane Endothelial cells and reticulin cells Contain valves One direction of flow Reticulin fibres hold in place
Lymph flow order
Tissue fluid from capillaries and cells goes to Capillary Vessel Node Trunk Duct
Lymph flow control
Vessels lie adjacent to veins and arteries, compression from these expanding can propel lymph Superficial and deep Contraction of muscles Smooth muscle cells in their walls Breathing Valves
Where is lymph not present
CNS (brain and spinal cord)
Lymphatic capillary vs Vein
Both have:
Valves
Low pressure
Lymph:
No cells present unless infection
Veins:
Lots of cells
Lymphatic trunks and ducts structure
Similar to larger veins
Larger valves (fibrocartilage)
Smooth muscle
Skeletal muscle and organ movement for flow
What is cisterna Chyli
Contains chyle from GI tract (central body region)
Where does upper right quadrant lymphatic drain to
Right lymphatic duct to the right subclavian vein/internal jugular vein
Where does the rest of the body drain to
Thoracic duct to the left subclavian vein/internal jugular vein
How many lymph nodes are there
600-700 in the body
3 most important lymph nodes
Armpit (axillae)
Groin (inguinal)
Neck (cervical)
Lymph node structure
Shaped like kidney
Multiple afferent vessels to enter (convex side)
1 single efferent vessel to leave (concave)
Each node has feeding artery and draining vein
Artery and vein run alongside efferent vessel
Capsule
Medulla (mature T lymphocytes)
What do lymph nodes contain
Follicles that contain immune cells (macrophages, dendritic, B cells, T cells and plasma cells)
Contain reticulin for connective tissue (made by reticular cells)
Follicular dendritic cells
In germinal centres of follicle
Antigen-antibody complex adhere to them
Cause proliferation of B cells and memory B cells
Lymph node draining an infection
Dendritic cell carries bacteria to lymph node
Macrophage engulfs + presents antigens
T cells activated
B cells activated
Plasma cells formed which produce antibodies
Antibodies go to blood
Difference between APC’s
B lymphocytes recognise antigens
Attacks invaders outside cells
T cells have to have foreign antigens presented to them by bodies own cells
Attacks invaders inside cells
Summary of lymph filtering
Traps antigen
Macrophage engulfs
Presents antigen
T lymphocytes activated
What do efferent vessels leave via
The hilum (indentation in node)
Where do the feeding artery and draining vein leave
Via the hilum
How do lymphocytes usually enter lymph nodes
Via feeding artery and leave via draining veins
How do dendritic cells enter nodes
Attached to pathogens via afferent lymph and leave via efferent lymph
What cells are responsible for inflammatory and immune response
Inflammatory - macrophages and neutrophils
Immune - B cells, T cells, plasma cells
What is the medical term for enlarged lymph nodes
Lymphadenopathy
What can cause lymphadenopathy
Infection (high number of lymphocytes to fight infection)
Cancers (can metastasise to lymph nodes via afferent lymph)
Lymphoma (malignancy of lymphoid tissue)
What are the primary lymphatic organs and where
Thymus (mediastinum, behind sternum and above heart) bone marrow (red marrow)
What are the secondary lymph organs and where
Spleen (left abdomen, behind stomach)
Tonsils (oropharynx and nasopharynx)
Appendix (lower right quadrant)
Payers patches (under mucosa of small intestine)
Thymus from birth
Fully formed and functional at birth
Involutes after puberty and becomes fat tissue
Function of Thymus
Maturation of T lymphocytes via thymic cell education
Thymus structure
Lobules seperated by septa
Capsule and septa made of reticulin fibres
Dense extra cellular matrix
What can changes in thymus lead to
Myasthenia Gravis and then Myasthenia crisis - inability to swallow due to weakened muscles
Function of spleen
Filters blood
Immune:
Antigen presenting
Activation and proliferation of B and T lymphocytes
Produce antibodies
Removal of antigens from blood (by macrophages)
Haemopoetic:
Recycles iron from erythrocyte Haemoglobin
Stores erythrocytes
Destruction of old, damaged or abnormal erythrocytes and platelets
Splenomegaly
Enlarged spleen from localised or systemic infection
At higher risk of rupturing and then internal bleeding
Splenectomy
Removal of spleen
Liver and bone marrow take over removal and destruction of old RBC
But more susceptible to infection from encapsulated bacteria
(Streptococcus pneumoniae, Neisseria meningitidus, Haemophilus Influenzae)
Waldeyers ring
Tonsils - adenoid (nose), palatine (ones everyone refers too), lingual (behind tongue)
Structure of tonsils
Nodules inferior to invaginations
Function of tonsils
Prevent pathogen ingress from oral, nasal and aural routes
Crypts increase SA
Why does swelling of tonsils occur
Contain microfold cells
Act as antigen presenting cells
Swelling from B and T lymphocyte proliferation
Appendix structure
Nodules inferior to surface invaginations
Lots of microfold cells
Function of appendix
Prevent pathogens from GI and ileum
Crypts increase SA
Payers patches structure
Nodules inferior to surface domes
Lots of microfold cells
Function of payers patches
Prevents pathogens from digestion
Functions of lymphatic system
Fluid balance (interstitial fluid back to circulation
Transports of fats and fat soluble vitamins (chyle)
Defence against pathogens and disease (filter lymph)
Storage and destruction of old erythrocytes (spleen/liver if no spleen)
What are sentinel lymph nodes
First node to receive lymph from primary tumour
Primary lymphoedema
Congenital (Milroys disease, missing endothelial cells in vessel)
Praecox
Tarda
Secondary lymphoedema
Swelling Neoplasia (cancer) Surgery Auto immune Infections (cellulitis and filariasis)
How can cancer cells travel
Via newly produced vascular system
Interstitial space
Through lymph
3 types of cancers where metastasis often occurs
Malignant melanoma, breast cancer, endometrial cancer
Old way to detect cancer
Axilla or pectoral are sentinel lymph nodes in breast cancer
Frozen section taken whilst in theatre
Checked and presence of malignant cells = mastectomy
New modern way to detect cancer
Flurography using radioactive dye
Only shows sections which are affected so not all lymph has to be removed
Reduces change of lymphoedema
Two infections that can cause lymphoedema
Cellulitis - obstruction of vessel
Filariasis - parasitic worm
Treatments for lymphoedema
Surgical stockings
Lympha press system (electronics massage system that pushes lymph up to be drained)
