Lymphatic system Flashcards
What are the functions of the lymphatic system?
Tissue drainage
Return of plasma and plasma proteins
Absorbed fat transport from gut
Immunity
Describe tissue drainage and the return of plasma proteins?
as the blood flows through the capillary bed , the pressure as we go from larger vessels to increasingly small vessels increases to a very high pressure. Forcing fluid out of endothelial walls of capillary bed into extracellular space. Then squeezes through the walls into the lymphatic vessels and then flows because of changes in pressure in the tissue they’re in.
Describe what lymph is made of ?
Lymph is fluid and plasma proteins only, but gains lymphocytes as passes from periphery to centre.
How does fat end up in lymphatic system?
If vessels draining the gut, becomes filled with fat. When do the gut, venous drainage goes directly to the liver for processing. But a lot of the fat goes into the lymphatic system which will flow back into central circulating system before can pass to liver. Fat will circulate more around body, could have negative effects for e.g. where it might be stored and fatty diseases
Describe flow?
Endothelial cells in the lymphatic vessel are not very well adhered together.
In a vein and an artery they are quite well adhered by a whole load of proteins. In a vein they are less well adhered and allows them to work like a flap valve- higher pressure outside than inside the fluid can pass from extracellular space into vessel. Because they have valves, each time we compress them- moves on a valve.
Why does protein accumulation occur?
Protein accumulation is because of changes in the water concentration and will lead to flow.
Where is the flow going?
deep flow of lymph from our organs and superficial flow of lymph from the periphery.
That deep drainage (which the superficial drainage drains into) largely follows the route of the supplying arteries, not draining veins. The lymph follows arteries that had supplied it, back to aorta.
Where are lymph nodes found?
found along the course of their lymphatic vessels. Sparse in the periphery and become increasingly numerous as pass towards trunk and centre.
Describe the physical appearance of lymph nodes?
a lymph node consists of a mass of lymphatic tissue that is surrounded by a fibrous capsule. Each lymph node is connected to an incoming and outgoing lymph vessel.
Lymph node has a blood supply and perfusing through is the lymph- at this point there is opportunity for exchange.
Antigen draining in lymph system can be exposed to lymphocytes in circulatory system.
What are preaortic lymph nodes?
anterior to aorta
What are paraaortic lymph nodes?
lie on either side of the aorta
What group of nodes do we find at arterial branches from the aorta?
arterial branches from the aorta are where we’ll find a group of nodes that have drained the lymph from the organs that that arterial branch supplied.
Describe superficial lymph nodes?
largely drains back to root of whatever bit is sticking out of the trunk
largely from skin and subcutaneous tissue
What are the rules of drainage?
Great saphenous vein also draining superficial tissues. Lymph is draining back to root of a superficial vein and superficial vein drains down into deep vein. The nodes follow same pattern as in abdomen, go to join back towards base of arterial roots.
What are nodes in groin called?
Inguinal
What are nodes in armpit called?
auxililary
Give examples of lymph node pathology?
Primary tumours (lymphomas) such as Hodgkin’s- tumour arises in lymph nodes
Secondary tumours as a result of metastasis from other sites- cancerous tumour cells arriving in lymph nodes after draining from primary area of tumour growth
Infections such as tuberculosis and glandular fever (mononucleosis)
Inflammatory hyperplasia.- very enlarged nodes. Can also be sign of an infection
What part of body drains into thoracic duct?
The entire left side of the body and the right lower limb and lower right abdomen
What drains into right atrium?
inferior vena cava and superior vena cava
What happens at the cisterna chyli?
accumulation point in abdomen
What does thoracic duct drain into?
venous system and a very short route back into heart. Then to be circulated around body
What is purpose of lymph system?
to keep balance of 8 L escaped in the periphery. Half absorbed at 2 large lymph ducts and half in lymph nodes
What are the two routes for absorbed substances from gut to get back to liver to be processed?
porto vein and arterial supply
Where does right lymphatic duct drain into?
superior vena cava
What veins are draining neck and upper limbs?
jugular, subclavian veins
what vein is draining posterior intercostal spaces?
azygous
What is a lacteal in a villus?
single blind start to lymphatic system. Collects lymph and fat in each of villi and flow back to nodes around aorta
Describe fat transport from gut?
Lymph returning from the small intestine is laden with absorbed fats, which will also drain to the SVC and eventually to the liver for absorption.
Where are lymphocytes generated and mature?
Thymus and Bone marrow (1o)
Spleen (2o)
Lymph nodes (2o)
Peyer’s patches (2o) (in intestine, accumulations of lymphoid tissue)
Tonsils
Give characteristics of the spleen?
Largest lymphatic organ
Upper left quadrant of abdomen (peritonised)
Contains large amount of blood, routinely discharged via smooth muscle action
What are central nodes around aorta also receiving?
drainage from abdominal organs and thoracic organs
