BL Lymphatics Flashcards
Describe the flow of lymph
Capillaries > vessels > trunks > ducts > right lymphatic duct OR thoracic duct (left)
Functions of the lymphatic system
- fluid balance
- transport of fats and fat-soluble vitamins
- defence against invading pathogens and disease
- storage of and destruction of aged erythrocytes
What is responsible for storage and destruction of aged erythrocytes?
Spleen
Liver can take over after splenectomy
How does the lymphatic system defend against invading pathogens?
- lymph nodes and other lymphatic organs filter lymph to removed microorganisms + foreign particles
- T + B lymphocytes + macrophages
Identify the cells of the lymphatic system
- lymphocytes - B+T cells + natural killer cells
- supporting cells - follicular dendritic cells + macrophages
Identify tissues of the lymphatic system
Mucosal associated lymphatic tissue (MALT):
- gut associated lymphatic tissue (GALT)
- bronchus associated lymphatic tissue (BALT)
Organ of the lymphatic system
Lymph nodes
Thymus
Spleen
Identify the lymphatic nodules of the lymphatic system
Tonsils
Peyer’s patches
Vermiform appendix
Function of the thymus in the lymphatic system
Primary lymphatic organ
Responsible for maturation of immature T cells
Function of the spleen in the lymphatic system
- Consists of red pulp - filters RBC
- Consists of white pulp - filters pathogens
- Contains B+T cells - adaptive immune function
- Stores +destroys old erythrocytes
- Clears encapsulated bacteria
What bacterial infections are patients with a splenectomy at an increased risk of and why?
Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus influenzae
Spleen is important in clearing encapsulated bacteria
Function of vermiform appendix
Prevents pathogens entering through the GI tract
Contains crypts and M-fold cells
What is the vermiform appendix?
An out punching from the caecum (first part of the large intestine)
Lower right quadrant of abdomen
What are Payer’s patches?
Collection of lymphatic nodules attached to the side of the ileum
Prevent pathogens entering the blood through digestion
Function of Payer’s patches
Prevent pathogens entering the blood through digestion
Organisation of the lymphatic system
Lymph
Lymph vessles
Lymphoid tissues and organs
Cells contained within tissues and organs
Location of the lymphatic system
Everywhere but the CNS
Adjacent to blood vessels
What is lymph?
Interstitial serum-like fluid (pH 7.4)
What is chyle?
Lymph from the GI tract
White + cloudy - contains fats + dissolved lipids
How much lymph is produced a day?
3-5 litres
Describe lymphatic capillaries
- Blind ended vessels - closed at one end
- Incomplete basement membrane with valves to allow fluid to flow one way
What three features help to move lymph?
- Skeletal muscle movement
- Pressure changes in thorax during breathing
- Pulsations of adjacent arteries - lymphangion compression
Compare lymphatic capillaries and veins
Similarities;
- low pressure
- valves present
Differences:
- no cells in lymphatic normally
Name of duct on the right side of the body in lymphatic system
Lymphatic duct
Name of duct on the left side of the body in lymphatic system
Thoracic duct
What is cisterna chyli?
Large container of chyle from GI tract
What does the lymphatic duct drain?
What does it drain into?
Upper right quadrant of body
Right subclavian vein/internal jugular vein
What does the thoracic duct drain?
What does it drain into?
Rest of body (not the upper right quadrant) - left side of body + everything under umbilicus
Left subclavian vein/internal jugular vein
Most clinically important lymph nodes
Neck - cervical
Groin - inguinal
Armpit - axillae
Chest - Pectoral region - especially women
Structure of lymph nodes
- Afferent lymph vessels enter at convex surface
- Efferent lymph vessels leave at concave surface
- Multiple follicles - nodules that contain immune cells
- made by reticular cells (reticulin - collagen III)
Immune cells found in lymph nodes
Macrophages
Dendritic cells
B+T cells
What are dendritic cells?
APCs that activate T cells in lymph nodes
Function of lymph node
Filters lymph fluid by trapping antigens from pathogens, processing + presenting them on APCs
What is lymphadenopathy?
Enlargement of lymph nodes due to activation of B cells by T cells
What is lymphoma?
Hodgkin’s vs non-Hodgkin’s lymphoma
Cancer of lymph node
- Hodgkin’s: treatable + curable
- Non-Hodgkin’s: treatable but incurable
Primary lymphatic organs
Thymus
Bone marrow
Secondary lymphatic organs
Lymph node
Spleen
Tonsils
Appendix
Payer’s patches
Primary vs secondary lymphatic organs function
Primary - production + maturation of immune cells
Secondary - trapping + presenting foreign antigens to lymphocytes
What growth factor induces lymphocyte proliferation?
Interleukins
Function of spleen
Immune function:
- activation + proliferation of B+T cells»_space; production of antibodies
- removal of large antigens from blood using macrophages
Haemopoietic functions:
- removal + destruction of old + damaged RBCs
- storage of RBCs
- retrieval of iron from haemoglobin
Function of tonsils
prevent pathogen entry through oral + nasal routes
What is lymphoedema?
Dysfunction in the lymphatic system resulting in swelling of lymph
Casues of primary lymphoedema
Genetic causes
Causes of secondary lymphoedema
Surgical removal of nodes
Infections
Cancers of the lymph nodes - lymphoma
Describe the role of sentinel lymph nodes in metastatic cancer
- First lymph node cancer cells drain into from a primary metastatic tumour in order to spread
- Used in detecting cancers
Treatments of lymphoedema
Lymph press system
- Pushes lymph up the body
- Only improves symptoms, doesn’t cure
Compare and contrast lymph nodes and nodules
- Lymph nodules do not have a defined fibrous capsules of connective tissue surrounding the tissue
- lymph nodules don’t filter the lymph fluid - no vessels
What is Hogkin’s lymphoma characterised by?
Reed sternberg cells
What is non Hodgkin’s lymphoma characterised by?
Increased proliferation of B or T cells
