Chapter 20 - lymphatic system Flashcards
What is the lymphatic system and what does it consist of?
returns fluids leaked from blood vessels back to blood
- network of drainage vessels (lymphatic vessels)
- fluid (lymph)
- structures that cleanse lymph (lymph nodes)
What is the function of lymphoid organs and tissues?
Provide structural basis of immune system
- body’s defense mechanisms
- spleen, thymus, tonsils, lymph nodes, other lymphoid tissues
What are the functions lymphatic vessels?
collect the excess protein-containing interstitial fluid and return it to the blood
- transport pathogens to lymph nodes and absorbed fats from intestine to blood
What are lymphatic capillaries, where are they not found.
blind-ended vessels that weave between tissue cells and blood capillaries
- bones and teeth
How are lymphatic capillaries operate in the brain?
- help drain ECF (inter and cerebro fluids) and their wastes
- malfunction plays a role in degenerative diseases (Alzheimer’s)
Why are lymphatic capillaries more permeable than blood capillaries?
- overlap loosely to form one-way minivalves anchored by collagen filaments, so increase ISF volume
How does the minivalves close and why is it important?
- pressure in lymphatic capillaries increase, the valve closes and prevents leakage
Which tissue is lymphatic capillaries even more permeable?
inflamed tissues, to help take up larger substances
What are lacteals in the small intestine and what is the structure set up?
a specialized set of lymphatic capillaries for absorption and transport of digested fat
- intestinal mucosa
How do large lymphatic vessels drain?
drain into larger and thinker-walled lymphatic vessels than to the subclavian veins
What is the collecting lymphatic vessels composition, location and formation?
- have all three tunica (thinner), valves and anastomoses
- In skin: travel in superficial veins or deep vessels of trunk travel with deep arteries
- larger vessels unite to form lymphatic trunk
How many lymphatic trunks are there and what are the 2 main pairings and one singluar one?
9
- Left: lumbar/ broncho mediastinal and Right: subclavian/ jugular trunks
- intestinal trunk
What are the 2 main ducts the trunks deliver lymph to?
- right lymphatic duct
- thoracic duct (larger)
What parts of the body does the right lymphatic duct serve and where does it drain?
- drains right upper limb and right side of the head and thorax
- venous circulation: right internal jugular and right subclavian
What parts of the body does the thoracic duct serve and where does it drain?
- drains the rest of the body
- venous circulation: left internal jugular and left subclavian veins
How do lymphatic vessels receive their own blood supply and what is it called when it becomes inflamed.
vasa vasorum
- severe inflammation is called lymphangitis (shown as a red streak on arm)
Lymph nodes - what is it composed of and what are the immune system cells?
- made of immune system cells found in lymphoid tissues
- 2 types of lymphocytes (T and B cells) protect the body against antigens
What are antigens and are the functions of the 2 types of lymphocytes?
A: anything that triggers an immune response
T lymphocytes: immune response; some directly attack infected cells
B lymphocytes: bind, produce plasma cells, which secrete antibodies that destroy cells with antigen
What is the difference between macrophages and dendritic cells?
M - engulfs cell and active T cells - granulomas
DC - capture and deliver antigens to lymph nodes to activate T cells
What is a lymphoid tissue?
component of the immune system
- provides activation and proliferation sites for lymphocytes
- ideal surveillance location for lymphocytes and macrophages
What is the lymphoid tissue made of and what resides in it?
reticular connective tissue
- in all lymphoid organs except thymus
- spaces between fibers is where lymphocytes to “live” when they return from patrolling the body
What is diffuse lymphoid tissue?
loose arrangement of lymphoid cells and reticular fibers
- in every body organ
What is lymphoid follicles (lymphoid nodules)?
tightly packed lymphoid cells and reticular fibers
- have germinal centers of proliferating B cells
- helps form larger lymphoid organs
Where are lymphoid follicles found?
- intestinal wall (of ileum) called Peyer’s patches
- the appendix
- MALT
- lymph nodes
- tonsils
Why can lymph nodes become a secondary cancer site?
- cells get trapped causing a bulge that is not painful
What is the primary lymphoid organs?
where T and B cells mature
- B cells mature in RBM
- T cells mature in the thymus
What is the secondary lymphoid organs?
where mature lymphocytes first encounter their antigens and become activated, include:
- lymph nodes and spleen
mucosa-associated lymphoid tissue (MALT) that form:
- tonsils, Peyer’s patches in small intestines and appendix
- diffuse lymphoid tissues