The Lymphatic System

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What are the

Question 8

What are the two types of duct and where does the two parts of the body drain to.

Answer 8

The ducts split off into two parts: the left Thoracic duct and the Right Lymphatic duct.
Lymphatic flow
The upper right quadrant drains into the right subclavian vein/internal jugular vein through the right lymphatic duct. The rest of the body drains into the left subclavian vein/internal jugular vein through the thoracic duct.

Question 9

What is the structure of the lymph nodes

Answer 9

Lymph nodes are shaped like a kidney. Each node has multiple afferent lymphatic vessels that enter via the convex surface. They also have a single efferent lymphatic vessel that leaves via the concave hills. Each lymph node has a feeding artery and draining vein that also enter and leave via the hilum.
They have multiple ‘follicles’ which are nodules that contain immune cells (macrophages, dendritic, B and T cells, plasma cells).
The main connective tissue fibres are reticulum (collagen 3) that are made by reticular cells.

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Question 14

What is the thymus

Answer 14

The Thymus is one of the primary lymphatic organs in the superior mediastinum. It is fully formed and functional at birth but involutes after puberty. It’s structure is similar to lymph node (with no hilum). It’s function is the maturation of bone marrow derived stem cells into immunocompetent T cells (Thymic cell education).

Question 15

What is the spleen

Answer 15

The spleen is a secondary lymphatic organ. It is the largest lymphatic organ with a very rich blood supply. It is inferior to diaphragm and posterior to stomach and functional at birth. It as a similar structure to lymph nodes but separated into white pulp and red pulp.
The spleen has immune functions (antigen presentation by APCs, activation and proliferation of B and T lymphocytes, production of antibodies, and removal of macro molecular antigen from blood), as well as Haemopoetic functions (removal of old, damaged erythrocytes, retrieval of iron from erythrocytes haemoglobin and erythrocytes storage.

Question 16

What are tonsils

Answer 16

Tonsils are a secondary lymphatic organ found in the oropharynx and nasopharynx. They are fully formed and functional at birth, and together constitute Waldeyers ring. The nodules reside inferior to surface invaginations (crypts).
It’s function is to prevent pathogen ingress through oral and nasal routes. They prevent pathogen ingress through aural route (adenoids and tubal tonsils). Crypts increase surface area.
Surface epithelia have micro fold (M-cells). These present antigens to underlying immune cells and swelling due to B-cell and T-cell proliferation

Question 17

What is the Appendix

Answer 17

The appendix is a secondary lymphatic organ. It’s is inferior to and attached to caecum (ascending colon). The nodules reside inferior to surface invaginations (crypts) and many M-fold cells in epithelial surface. It’s function is to prevent pathogen ingress through GI routes. It prevents pathogen ingress arriving from ileum and crypts increase surface area.

Question 18

What are Diffuse Lymphatic Nodules (MALT/GALT)

Question 19

What are Payers patches

Answer 19

Payers patches is a secondary lymphatic organ. They are inferior to and attached to side of ileum. The nodules reside inferior to surface domes and many M-fold cells in epithelial surface. The function is prevention of pathogen ingress through digestion.