Lecture 23 - Lymphatic System Flashcards
What is the alternate name for the Lymphatic System?
Reticuloendothelial system (RES)
Where is lymph NOT found?
In the CNS (Brain and spinal cord)
How is the Lymphatic system organised?
Lymph
Lymphatic vessels
Lymphoid tissues and organs
What is the pH of lymph?
7.4
What is Chyle?
Lymph from the GI tract that contain fats and dissolved lipids so is cloudy
Contains CHYLomicrons and fat sol vitamins
What are the smallest type of lymphatic vessels to the largest?
Lymphatic capillaries
Lymphatic vessels
Lymphatic Trunks
Lymphatic Ducts
How are lymphatic capillaries held in place and what type of fibrous protein makes these fibres?
Reticulin fibres
Made by Collagen III
What is unique about the endothelial cells of lymphatic capilaries?
They are not attached to a basement membrane
They are overlapping
What contributes to the flow of lymph through lymphatics?
Muscle contraction from surrounding muscle helps propel lymph
The lymphatic trunks and ducts have smooth muscle cells in there walls preventing them from expanding to much. This aids the flow of lymph against gravity
Where are lymphatic vessels found and how does lymph flow?
Near cardiovascular vessels( capillaries, arteries and veins)
Unidirectional
Flows superficial to deep (outside to inside)
How does a lymphatics capillary compare to a vein?
Both low pressure systems
Both have valves
Lymph capillaries don’t have cells unless infection
Lymph capillaries squeezed by veins and arteries propelling lymph
Generally how does lymph flow?
Excess tissue fluid collected by Lymphatic capillary
Lymphatic capillary——> Lymphatic vessel
Lymphatic vessel ——> lymphatic node
Lymphatic node——> lymphatic trunk
Lymphatic duct ——> Drains lymph back into venous circulation
What duct drains lymph from the the Upper Right Quadrant (RUQ) back into venous circulation?
What is the name of the blood vessel that it drains it into?
The Right Lymphatic duct
Into the Right Subclavian vein
What duct drains lymph from the body that is NOT from the RUQ?
What is the name of the blood vessel t drains it into?
The Thoracic duct
Left subclavian vein
Name 3 clinically important lymph nodes
Cervical lymph nodes (neck)
Inguinal lymph nodes (groin)
Axillae lymph nodes (Armpit)
What is the structure of a Lymph node?
Kidney shaped
Have nodules called Follicles
Each nodule has multiple afferent lymphatic vessels and efferent lymphatic vessels
What is the Concave hilum of the lymph node?
Where the single efferent lymphatic vessel leaves the lymph node
Where the feeding artery and draining vein enter and leave the lymph node
Which region of the lymph node contains the nodules/follicles/germinal centres of the lymph node?
Cortex
What cells are contains within the follicles/nodules of a lymph node?
Immune cells:
-Macrophages
-Dendritic cells
-B and T lymphocytes
-Plasma cells
What is the main connective tissue fibre found in a lymph node?
Reticulin made by collagen 3
Made by reticular cells (modified fibroblasts)
How can you identify a follicle/nodule/germinal centre in a lymph node?
Outer ring of dark purple
Inner lighter pink centre
What is the difference between B cells and T cells?
T cells attack invaders that invade the inside of cells
B cells attack invaders outside cells
What is a follicular dendritic cell?
What is the function of a follicular dendritic cell?
A type of dendritic cell which resides in the follicles of the lymph node
They act as Professional Antigen Presenting Cells (APCs)
They cause B cell proliferation in memory B cells
Last for many years (immunity)
What is the function of T helper cells?
They stimulate/help B cells make antibodies by binding to B cells with the antigen receptor for that pathogen
Which of the lymphocytes B or T need to be presented with the antigen?
T lymphocytes need to have the antigen presented to them
What is the importance of Macrophages and Follicular dendritic cells in the immune response?
They acts as APCs
They present antigen to naive T cell
Naive T cell activitated
Produces T memory cells and T helper cells
T helper cells help B cells proliferate and produce antibodies
What is Lymphadenopathy?
Enlarged lymph nodes
What can cause Lymphadenopathy?
Infections (germinal centres/nodules fill with lymphocytes)
Cancers can mestastatise to lymph nodes
Lymphoma (malignancy/cancer of the lymphoid tissue itself)
What are 2 types of lymphoma?
Hodgkin lymphoma (treatable and curable)
Non-Hodgkin lymphoma (incurable/fatal)
What are the 2 primary lymphatic organs and where are they located?
Thymus - in the mediastinum
Bone marrow - red marrow of bone
What are the secondary lymphatics organs?
Spleen
Tonsils
Appendix
Payers patches
Diffuse lymphatic nodules
Lymph nodes
What is the structure and function of the Thymus?
Similar to lymph node but with no hilum
Responsible for maturing immature T cells to mature T cells
What is a Myasthenia crisis?
Changes to Thymus due to Myasthenia gravis cause inability to swallow and breath due to weakened muscles
What is the structure and function of the Spleen?
Similar to lymph node but separated to red and white pulp
Both immune and haemopoietic, it filters blood look lymph nodes filter lymph
Describe the position of the spleen
Inferior to the diaphragm and posterior to the stomach
What are the immune functions of the spleen? (White pulp)
Antigen presentation by APCs
Activation and proliferation of B and T lymphocytes
Remove large antigens from blood
What are the Haemopoietic functions of the spleen? (Red pulp)
Removes and destroys old,damaged, abnormal erythrocytes and platelets
Retrieves iron from haemoglobin of broken down RBCs
Erythrocyte and platelet storage
Why is a ruptured spleen so dangerous?
Rich blood supply
Severe loss of blood if ruptured, blood would fill abdomen
What is a splenectomy?
Surgical Removal of the spleen
What is the body at risk of following a splenectomy?
Infection from encapsulated bacteria and malaria
List 3 encapsulated bacteria
NHS
Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
What can cause Splenomegaly?
Enlarged in response to local infection
Enlarges in response to systemic infection (glandular fever, malaria, septicaemia)
What are the 3 tonsils and where are they located?
Adenoids (nasopharynx)
Palatine tonsils (oropharynx)
Lingual tonsils (oropharynx)
Where do the nodules reside in the tonsils?
Below surface invaginations in regions called crypts
Crypts increase surface area
What is the function of the tonsils?
Prevent pathogen ingress through oral and nasal routes
Which of the tonsils are only visible when swollen?
Lingual tonsils
What are the most visible tonsils called and what does white patches on it when swollen indicate?
Palatine tonsils
White patches indicate that the infection is from Group A Strep bacteria
Aka Strep.pyogenes
What is the term to describe the 3 tonsils together? (Adenoid, Palatines and lingual tonsils?
Waldeyers ring
Where is the Vermiform appendix located and what is its structure?
Inferior and attached to the caecum
Nodules inferior to the surface invaginations know as crypts
What is the function of the Vermiform appendix?
Prevents pathogen ingress through GI routes
Prevent pathogen ingress from ileum
What does MALT stand for?
Mucosa-associated lymphoid tissues
What type of Associated lymphoid tissue are the payers patches?
GALT = appendix/payers patches
Where are payers patches located and what is there function?
Inferior and attached to ileum
Prevents pathogen ingress through digestion
What are the 4 key functions of the lymphatic system?
Fluid balance (returning interstital fluid to circulation)
Transporting fat and fat sol vitamins
Defence against pathogens and disease
Storing erythrocytes and destroying eythrocytes
What is a sentinel lymph node?
The first node to receive lymph form area of a primary tumour
Why do Sential lymph nodes swell withi metastatic cancers?
Cancer cell breaks off fro tumour (exosome) and invades myeloid cell in sentinel node
Causes proliferation of cancerous cells. Abusing the sentinel node to swell
What are the 2 ways which Sentinel nodes can be used to detect cancer (e.g breast cancer)?
First set of lymph nodes that will swell will be the Axilla or pectoral nodes
A frozen section can be taken in theatre to identify malignant epithelial cells
Or fluorescent dye injected into tumour, dyes tumour and sentinel lymph node so all the tumour and affectd lymph node can be removed
What is lymphodaema?
Swelling due to build up of lymph fluid in body
What is Primary lymphodaema?
It is lymphodaema with congenital cause
So born with defect in lymphatic system
What is secondary lymphodaema?
Lymphodaema caused by damage to the lymphatic system that is not a congenital cause
It developed properly but Is now damaged
What infections can cause Lymphodaema?
Cellulitis (bacterial)
Filariasis (elephant Itis) Parasitic worm invades lymph
What is the lympha press system?
Use to treat lymphodaema by pushing fluid up to other lymph nodes
Problem: if cause of lymphodaema is cancer/metastatic then you are spreading the cancer
What are the 4 functions of the Lymphatic system?
-Removes interstitial fluid from tissues
-Absorbs and transports fatty acids and fats as Chyle from the digestive system
-Transports whitest blood cells to and from the lymph nodes and back into the bones
-Transports antigen-presenting cells like dendritic cells to the lymph nodes where the immune response is stimulated
