The Lymphatic System Flashcards
What are the 2 Parts of the Circulatory system?
Cardiovascular and Lymphatic
What is Lymphatic system?
Similiar to CV but forms basis of Immune System
What are the 3 Components of the Lymphatic System?
- Extensive network of Capillaries and collecting Vessels
- Lymph Nodes
- Lymphoid Organs
How is Interstitial Fluid formed?
More Fluid with plasma proteins leaving Capillaries than entering it, the fluid accumulates in Intercellular Spaces
What can the build up of Plasma Proteins lead to?
Oedema
What happens to Plasma Proteins when they cant re-enter capillaries?
Enter Lymphatic Vessels
What type of System is Lymph whilst flowing to the heart?
One-way system, begins in tiny lymph capillaries
What type of Lymphatic Vessels are they?
Capillary -> Collecting Vessel -> Trunk -> Duct
How does fluid get into Interstitial Space?
Hydrostatic and Osmotic pressures at arterial ends of capillary beds force it toward venous end
What happens to the 3L/day Institial Fluid leaked and not absorbed by the capillaries?
They need to return to the blood
Where does Lymph Transport begin and what are the exceptions?
Lymph Capillaries and Bone, Bone Marrow, Teeth, CNS
What is the Lymph Capillaries?
Similiar to Blood Capillaries but V. Permeable
What are the 2 Structural Modifications of the Lymph Capillaries?
- Endothelial cells looseley overlap to create MINI-VALVES
- Endothelial cells Anchored to Surrounding structures by fine filaments, expose gaps in capillary wall but close to avoid leakage
What happens when the tissue becomes inflamed?
The Lymph Capillaries take up large particles e.g Debris, Pathogen, Cells
What filters and examines the particles?
Lymph Nodes
What are Lacteals? describe them?
Highly Specialised Lymph Capillaries in Villi of Intestinal Mucosa
Lymph is milky white due to carrying digested intestinal fats called CHYLE
Describe Collecting Vessels?
3 tunics like Veins which are/have
thin-walled, more internal valves, anastomising
Where do larger Lymphatic Vessels recieve Blood supply from?
Vaso Vasorum
What do the Lymphatic Collecting Vessels and Lymphatics travel with?
Collecting Vessels with Superficial Veins
Deep Lymphatics travel with Deep Arteries
What does Lymphatic Trunks do?
Drain large areas of the body, named after the area they drain lymph from i.e Lumbar, Subclavian
What are the 2 Types of Lymphatic Ducts?
- Right Lymphatic Ducts - drains lymph from right upper arm, right side of head, thorax
- Thoracic Duct - Larger arises from CISTERNA CHYLI, drains rest of body
How do the Lymphatic Ducts work?
Each Ducts empties Lymph into Venous Circulation at junction of internal jugular and subclavian veins
What is the Mechanism of Lymph Transport?
Pump-less so slow moving, same as veins i.e
milk actions of muscles, use of valves, rhythmic contractions of smooth muscles and breathing-induced pressure change
What is Lymphoid Tissue?
Loose Connective tissue (important for immune tissue) in all L. organs except Thymus
Macrophages live on fibres and Lymphocytes reside in spaces temporarily
What 2 ways are Lymphoid Tissues ‘Packaged’?
- Diffuse - in most body organs inc Mucous membranes and Lymphoid organs
- Follicles/Nodules - Solid, Tight Packed with Germinal centres containing B Cells e.g in Lymph nodes
How do Lymph Nodes work?
Lymph filtered through LN that cluster along lymphatic vessels of the body, provides protective function via Phagocytes and activate immune system
Where are the Lymph Nodes?
They cluster where lymphatic vessels converge to form trunks e.g inlingual, axillary
What do Lymph Nodes look like?
small bean-shaped organs, contain fibrous capsule from which connective tissue (trabeculae) form, emerge and divide into nodes
Provides support to residing L cells
2 regions, outer cortex - inner medulla
What does the Lymph Node Cortex Region look like?
densely packed follicles with germinal centres, dendritic cells wrap around follicles to seperate from T-Cell interspaces (for immune surveillance)
What does Lymph Node Medulla Region look like?
Contains Cords inward extensions of the cortex which contains L’s and Plasma Cells
What are Lymph Sinuses?
Spanned by reticular fibres, enter nodes and phagocytose materials
How does Lymph enter Afferent Lymphatic Vessels?
on Convex side, moves through large subscapular sinus into smaller sinuses through to the medulla
How does Lymph leave Efferent Lymphatic Vessels?
At Hilus, causes Lymph stagnation, passesseveral nodes before its cleaned
Describe the Lymphoid organ the Spleen?
Largest, soft rich-blood organ, fist size on left abdomen, served by large splenic artery and s.vein that enter hilus on concave side
What are the Functions of the Spleen?
Immune serveillance, Cleans blood, Store RBC, Store Platelets, Site of RBC production
Thin capsule with trabeculae
What are the 2 Distinct Regions of the Spleen?
- Areas of L on reticular fibres - white pulp and forms ‘cuffs’ around arteries
- Areas of red cells, venous sinus, splenic cord and red pulp
Describe the Lymphoid organ the Thymus?
Bilobular organ in lower neck, prominent in newborns (turns into fatty tissue with age) , secretes thymosin
Describe the Thymus Structure?
Compare to cauliflower head, florets the thymic lobules with outer cortex (dark-stain - rapid divide) and inner medulla (light stain- fewer L’s)
What does the Light-Staining Medulla of thymus contain?
Hassals or Thymic Corpuscle - Responsible for conversion of self-reactive T-Lymphocytes
In what 2 Ways does the Thymus differ from other L organs?
- Functions only in T-cell maturation, doesnt fight antigents directly Blood-thymus-Barrier
- Stroma (framework) has star shaped endothelial cells, secrets hormones
Describe the Lymphoid organ the Tonsils?
smallest, ring of tissue around entrance to throat
Gather and remove pathogens entering in
What are the 4 Types of Tonsils?
Named by location;
- Palatine - larger located at either side of oral cavity (often infected)
- Lingual (base of tongue)
- Pharyngeal (adenoids - posterior walls of nasopharynx)
- Tubal (surrounding of auditory tubes)
What does the Tonsils contain?
nodules with germinal centres
Exterior surface- squamous epithelium deep into tonsils to from CRYPTS that trap bacteria (killed in L tissue- memory immune cells)
What is Peyers Patches?
Large isolated cluster of nodules (similiar to tonsils) -located in wall of ileum
What is Appendix?
Cluster of Nodules
What does Peyers Patches and Appendix do?
Destroy bacteria, Generate memory for immunity, MALT for resp and digestive tract protection
