42 - Lymphatics Flashcards
What are the functions of lymphatics
Drains interstitial fluid
Transports dietary lipids from GI tract to blood
Protects against invasion through immune responses
Pathway for spread of malignancy
How much lymph remains in the interstitial fluid?
3L/day
What is the lymphatic plexus
Collection of lymphatic vessels in the capillary bed
What is the flow of lymph
Lymphatic plexus - lymphatic capillary - lymphatic collecting vessels - lymph nodes to lymph trunk - lymph duct to right side of heart
How many lymph trunks are there in total?
9
What is lymphatic filariasis
Also knows as elephantitis
obstruction of vessels/ducts so lymph cannot drain
caused by mosquitos
How do lymphatic vessels aid the flow of lymph
Low pressure conduits
What other mechanisms are there which aid the flow of lymph
Milking action of active skeletal muscle
Numerous valves
Pressure changes in thorax
How do lymph nodes (principle lymph organ) filter lymph
o Macrophages remove and destroy microorganisms and debris
What does the right lymphatic duct drain and where does it end?
= Drains right upper quadrant
= Right side head, neck, thorax and right arm
= Duct ends in RSCV at junction with IJV (right venous angle)
What does the thoracic duct drain and where does it end?
= Drains rest of body
= Begins in abdomen as cisterna chyle
= Duct ends at left venous angle
What does the superficial component drain and what is it made up of
Drains the skin
Cervical nodes
Axillary nodes
Inguinal nodes
What are the two types of inguinal lymph nodes and what do they drain
Horizontal (run superficial to inguinal ligament)
• Superficial lymphatics from anterior abdominal wall, the perineum, and the external genitalia (excl. testes)
Vertical (lie along termination great saphenous vein)
• Majority of superficial lymphatics from leg
vertical and deep inguinal lymph node clearance
Inguinal lymph node clearance during surgery to remove malignant melanoma from sole of foot
o Horizontal (superficial) lymph node clearance
Vulva cancer
Scrotal cancer
Penis - deeper inguinal lymph nodes
Testes - preaortic
What do kerley B lines show
Pulmonary Oedema
Ladder up the side - engorged interlobular lymphatic
inc pulmonary VENOUS pressure
When does lymphoid tissue increase in mass to twice and adults size?When does lymphoid tissue regress back to adult levels?
- twice adults mass - 6-9 years of age
- regresses by puberty
What happens to lymph nodes as you age
The number and size decreases
Some lymphoid elements are lost
nodes are more fibrotic and fatty - impaired ability to resist infection
Where else can lymphoid tissue aggregate?
Spleen Thymus Peyer's patches of intestine Tonsils/adenoids Myeloid tissue in bone marrow
What is the tissue make up of lymphoid organs
Reticular connective tissue
however only lymph nodes filter lymph
Functions of spleen
Site for lymphocyte proliferation Immune surveillance and response Blood cleansing function Stores/release products of RBC Erythrocyte production in foetus Stores platelets
What are the blood cleansing functions of the spleen?
Extracts aged and defective blood cells and platelets
Macrophages remove debris and foreign matter
Where is the thymus
Inferior neck and superior thorax deep to the sternum
What does the thymus secrete and what does it do?
Secretes thymopoietin and thymosins – cause T lymphocytes to become immunocompetent
When does the thymus grow and atrophy?
Grows in 1st year (highly active)
After puberty atrophies
What do the tonsils do
Gather and remove some pathogens entering the pharynx in food or inhaled air
Name the 4 tonsils
o Palatine
o Lingual
o Pharyngeal (adenoids if enlarged)
o Tubal tonsils
What are peyer’s patches and where are they located?
Large isolated clusters of lymphoid tissue located in wall of distal small intestine
What are the functions of peyer’s patches?
o Destroy bacteria and so prevent pathogens from breaching intestinal wall
o Generate many memory lymphocytes for long term immunity
