Lecture 9: The Lymphatic System Flashcards
What immune response is the lymphatic system involved in?
Adaptive and innate immune response
Name some organs/tissues that are in the lymphatic system (7 in total)
Lymphocytes
Spleen
Bone Marrow
Thymus gland
Diffuse lymphatic tissue
Lymph nodes
Lymph vessels
What is the main transport vessel for cells and large molecules to migrate from tissue back to blood?
Lymph vessels
Where can you find lymphatic tissue?
All throughout the body
What tissues specifically can you usually find lymphatic tissue?
Lamina propria of tissues
Why can you find lymph vessels surrounded by smooth muscle?
Smooth muscle helps with the movement of the lymphatic vessels.
This is because the fluid flows at a low pressure.
Why do lymph vessels need the help of skeletal muscles?
The contraction of skeletal muscle can help move the fluid along
How do lymph vessels help WBCs?
WBCs use the lymph vessels to travel around the body.
Lymphocytes will migrate out of the tissue into lymp vessels (kind of like a subway)
What are the two specialised cells embedded in lymphatic tissue/nodules called?
Plasma cells
Eosinophils
ToF: Lymphatic tissue are un-encapsulated
True
ToF: Lymphatic nodules and lymph nodes are the same
False
What is a lymphatic nodule? Describe (3 points)
Dense masses of lymphocytes and macrophages.
Not encapsulated (does not have a distinct outer boundary separating them from surrounding tissues)
Small, localised clusters of lymphatic tissue (found throughout the body)
What is a lymph node? Describe (3 points)
Small, bean-shaped structures located along the lymphatic vessels
Acts as filter for lymphatic fluid that circulates throughout the lymphatic systems, removes foreign substances/waste products
Encapsulated (surrounded by a fibrous capsule, separated from surrounding tissues)
Where are lymphatic nodules found? (4 points)
Associated with the Alimentary canal
Tonsils: Adenoids (pharyngeal tonsils), palatine and lingual tonsil
Ileum: Peyer’s Patches
Appendix
What does a lack of encapsulation in the lymphatic nodules cause?
Lymphatic nodules are more diffuse and less organised.
What are some similarities between lymphatic nodules and lymph nodes? (4 points)
Contains lymphocytes
Involved in filtering and removing foreign substances and waste products
Both can become enlarged in response to infection/inflammation
Can both be affected by lymphoma
ToF: Lymphatic nodules are encapsulated
False
ToF: Lymph nodes are encapsulated
True
ToF: Lymph nodes are un-encapsulated
False
What is the mantle zone in the lymphatic nodule?
Layer of lymphocytes that surrounds the germinal centre in a lymphatic nodule.
Comprised mainly of B-cells
Where can you find the germinal centre?
Lymph nodes
Lymphatic Nodules
What does the germinal centre do?
Site where B-cells mature and differentiate into plasma cells that produce antibodies.
What surrounds the germinal centre?
Mantle zone
What does the Mantle zone do?
Provides support for the maturation and differentiation of B-cells
Where is the mantle zone located in the lymph node?
Found on the outer edge of the lymph node.
Why is the mantle zone important in the immune response? (L)
Helps regulate the production of antibodies by B-cells by exposing B-cells. The B-cells that recognise a specific antigen, undergo clonal expansion and differentiate into plasma cells.
Therefore a large amount of specific antibodies are produced to neutralise the invading pathogen
What size are lymph nodes?
1mm-20mm
Where can lymph nodes be mostly found even if they are distributed throughout the body?
Axilla (under the shoulder joint where the arm connects to the shoulder)
Groin / (0) \
Mesentery (fold of membrane that attaches the intestine to the abdominal wall and holds it in place)
What is each lymph node supplied by?
2 lymph vessels
One afferent (carries into the node)
One efferent (carries fluid and cells away/out)
What is the name of the network that supports the lymphocytes?
Reticular network
What is the reticular network made up of?
Reticular fibres (type of collagen fibre) produced by reticular cells
What is the role of the sentinel lymph nodes?
Scans for antigens and activated lymphocytes
What does it mean if there are activated lymphocytes found in the lymph fluid?
Sign of an Infection
Why are sentinel nodes important in the context of cancer? (L)
When cancer cells break away from the primary tumour, they can enter the lymphatic system and be carried away to nearby lymph nodes.
The sentinel nodes are the first lymph nodes that these cancer cells are likely to reach.
By examining the sentinel node, it can be determined if have spread beyond the primary tumour and intro the lymphatic system