Lymphatics Flashcards
What is lymph?
It is an ultrafiltrate of blood plasma, formed by seepage of blood fluid across capillary walls.
What are the primary functions of the lymphatic system?
- remove and filter lymph
- add antibodies and return recirculating lymphocytes back to circulating pool
- return ECF and plasma proteins to blood
What does lymphatic drainage help diagnose? How is it clinically related to this?
Cancer.
Proximity of lymphatic system to many tissues and organs allows cancer cells to travel through it to other parts of the body. If the cancer cells are not trapped and destroyed in lymph nodes, the cancer cells can reach different areas of body and metastasize.
What are the TNM general classifications of malignant tumors?
T (0-4): size of primary tumor
N (0-3): degree of spread to lymph nodes
M (0/1): present of metastasis
(See slide 9 for specifics)
What are some conditions caused by damage/disruption of the lymphatic system?
Lymphedema: swelling due to damage/malformation of lymphatic system.
Lymphatic Filariasis: infectious; caused by nematode worms
Lymphedema Distichiasis: hereditary, caused by mutations in FOXC TF gene
Note: last two can cause elephantiasis
What are the primary conducting pathways of lymph?
Lymph Capillaries
Lymphatic Vessels
Lymphatic Ducts (trunks)
Describe lymph capillaries.
- thin-walled vessels lined with endothelium
- incomplete/discontinuous basement membrane
- end blindly in extracellular spaces to retrieve lymph
- anchoring filaments hold it in place
- drain into lymphatic vessels
NOTE: differentiate from blood vessels = there will be no blood visible in lymph capillaries
What are some examples of larger lymph capillaries?
Lacteals of intestinal villus
Lymphatic capillary in the liver (part of portal triad)
Describe lymphatic vessels.
- relatively larger lumen than blood vessels of comparable size
- walls are thicker than that of lymph capillaries
- conspicuous valves ensure unidirectional flow
- flow is determined by pressure from neighboring structures
- DEAD GIVEAWAY: nuclei will protrude into lumen.
Describe lymphatic ducts (trunks).
- similar to veins (both have valves), but lymphatic ducts have more smooth muscle in the tunica media than veins
- empty into the great veins in the base of the neck
The two lymphatic ducts of the body are?
Right lymphatic and thoracic duct.
What is diffuse lymphoid tissue? What are its identifying traits?
A cluster of lymphoid tissue cells that whose border is not sharply demarcated.
It typically sits beneath the lamina propria of the epithelium and does NOT have a capsule of any kind.
What are lymph nodules? What are their identifying traits?
Dense aggregations of lymphoid tissue that are more organized than diffuse lymphoid tissue.
There are two types: primary and secondary. Note that primary is simply a cluster of densely packed lymph cells, while secondary has a paler center called a germinal center (B cells) surrounded by a cap of small cells (T Cells).
What are the three main types of lymphoid tissue and where would they be found?
MALT: Mucosa-Associated Lymphoid Tissue (Ex. Glands)
BALT: Bronchus-Associated Lymphoid Tissue (Ex. Bronchioles)
GALT: Gut-Associated Lymphoid Tissue (Ex. Intestines)
What is a lymph node? What is its function?
A small organ that occurs along the length of lymphatic vessels.
It filters the lymph, removing undesirable cells, invading microorganisms, and particulate matter. It also participates in the immune response by producing lymphocytes.
