L18 : Cells and tissues of the lymphatic system Flashcards
What is the function of lymphatic system?
- Fluid balance
- Transport of fats and fat-soluble vitamins
- protection against pathogens
What does the lymphatic system consist of?
- Lymph
- Lymphatic vessels
- Lymphoid tissues and organs
- cells within tissues
What is a lymph?
- A thin fluid that resembles plasma
- pH 7.4
- lower amounts of proteins
What is a chyle?
- lymph that arises in GI tract
- white, cloudy substance
- contains fats and dissolved lipids (chylomicrons and fat soluble vitamins)
How much lymph is produced and recycled each day?
3-4 litres
What aids the flow of lymph?
- valves
- smooth muscle in wall
- contraction of muscle for deep lymphs assing through them
- skeletal muscle movement
- pulsation of adjavent arteris
What is the characteristics of lymph vessel?
- lie adjacent to cardiovascular vessel
- porous and the tips
- arranged into superficial and deep
- flow from superficial to deep
- valves, smooth muscle and anchoring filament (retiulin fibre)
- no cells in lumen
What is a lymphatic duct?
- Large lymphatic vessel that empties lymph into one of the subclavian veins
What are the two lymphatic ducts and what are their functions?
- Right Lymphatic Duct : drains lymph from upper right quadrant into right subclavian vein
- Thoracic duct : drains lymph from rest of the body into left subclavian vein
What are the clinically important lymph nodes?
- cervical
- inguinal
- axillae
What is the characteristics of Lymph nodes?
- kidney shaped
- multiple afferent lymphatic vessels enter convex surface
- 1 efferent lymphatic vessel leaves concave hilum
- has feeding artery and draining vein at hilum
- multiple follicles
- Reticulin
*hilum - portion of lymph node where efferent vessel exits
What is the function of Lymph node?
- Filters lymph as it percolates on its way to the vascular system
- traps and process antigen
- macrophage presents antigen to t cells
How does the majority of lymphocytes enter the lymph nodes?
- Majority enter via feeding artery and leave in the efferet lymphatics, some in lymph
- Majority leave via efferevt lymphatics
How do dendretic cells enter the Lymph nodes?
they enter with pathogens within lymphs
How many lymph nodes are there in th ehuman body?
about 700
What is the function of B cell and T cell in Lymph node?
- B cell :
- proliferate to form plasma cells and B memory cells
- Secrete antibodies
- T cells :
- directly attack cells with antigenic material
What is lymphadenopathy?
Enlarged lymph nodes
What causes lymphadenopathy?
- germinal centres fill with lymphocytes during infection
- Cancers metastasise to lymph nodes via afferent lymphatics
- lymphoma
Where can lymphodenopathy occur ?
all the nodal regions and can affect all lymphatic organs
What are the lymphatic organs?
- Thymus
- spleen
- tonsils
- appendix
- payer’s patches
What is the characteristics and function of thymus?
Characteristics
- located at superior mediastinum
- stops growing after puberty and replaced with adipose tissue
- only efferent lymphatic vessels
Function
- provide an inductive environment for development of T cells from haemopoietic progenitor cells
What is the characteristics and function of spleen?
Characteristics:
- largest lymphatic organ
- rich in blood supply
- inferior to diaphragm, psoterior to stomach
- seperated into white pulp and red pulp
- only efferent lymphatic vessel s
Function
- Immune function
- antigen presentation by APCs
- activates and poliferates B and T cells
- Haemopoietic functions
- remove and destroys old damage erythrocytes and platelets
- stores erythrocytes and lymphocytes
What is splenectomy and what is the risk associated with it?
- surgery to remove entire spleen
- increase risk of infection by encapsulated bacteria and malaria
Which organs can take over the role of spleen?
Liver and bone marrow
What is the characteristics and function of tonsils?
Characteristics
- located at oropharyx and nasopharyx
- together forms Waldeyer’s ring
Functions
- prevent pathogen ingress through aural, nasal and oral routes
*
What causes swelling of tonsils?
- Surface epithelia have many m cells
- present antigens to underlying immune cells
- swelling due to B and T cells proliferation
What is the characteristics and function of vermiform appendix
Characteristics :
- inferior to and attached to caecum
- nodules reside inferior to surface invaginations
- many M fold cells
Function :
- prevents pathogen ingress from ileum
What is the characteristics and function of payer’s patches
Characteristics
- inferior to and attached to side of ileum
- nodules reside inferior to surface domes
- many M-fold cells in epithelial surface
Function
- prevents pathogen ingress through digestion
What is a sentinel lymph node?
set of node to which cancer cells are most like to spread from a primary tumour
Tissue sample from which node is required for biposy of breast cancer?
pectoral node
What is a mastectomy?
surgical removal of breast with malignant epithelial cells
What are the ways to remove cancer through sentinel lymph nodes?
- Flurography via pectoral node
- mastectomy using probe
What are the types of lymphoedema?
