Chapter 20 - Lymphatic system and organs Flashcards
What does the lymphatic system do?
Returns interstitial fluids and plasma proteïns leaked from blood vessels back to blood
From which parts does the lymphatic system consist?
Lymphatics, lymph and lymph nodes
What is the function of lymphoid organs and tissues?
Provide a structural basis of immune system by housing phagocytic cells and lymphocytes
What are lymphoid organs?
Spleen, thymus, tonsils, lymph nodes, other lymphoid tissues
How much interstitial fluid circulates the lymphatic system per day?
3 litre
What is the new name of interstitial fluid when it gets into the lymphatics?
lymph
Where does the fluid come in and out in the lymphatic system?
It is forced out cleft of capillaries and returns to blood at venous end
What causes continuous mixing of fluid between plasma and interstitial fluid?
Bulk fluid flow acroos capillary
On which two opposing forces does the direction and amount of fluid flow depend?
Hydrostatic pressures and colloid osmotic pressures
What kind of force is hydrostatic pressure?
A force exerted by fluid pressing against wall
What is the difference between HPc and HPif?
HPc is pressure that tends to force fluids through capillary walls and HPif is a pressure pushing fluid back into vessel
What kind of pressure is colloid osmotic pressure?
A pressure created by nondiffusible plasma proteins pulling water back into capillary
What comprises all forces acting on capillary bed?
Net filtration pressure (NFP)
What is the name for the net fluid flow out at arterial end and in at venous end?
filtration and reabsorption
When does edema occur?
If fluids are not picked up from tissues
How is the flaplike minivalve formed?
Endothelial cells forming the walls of lymphatic capillairies overlap to form flaplike minivalves
How are capillaries anchored to connective tissue?
With filaments
When are the minivalves closed?
Higher pressure on the inside
What are collecting lymphatic vessels?
Lymph capillaries drained into inceasingly larger vessels
Out what parts does a larger lymphatic vessel exist?
collecting vessels, trunks and ducts
What is the difference between a lymph and blood vessel?
Thinner walls and more anastomose
What is a lymphatic trunk?
An union of largest collecting vessels
Where does lymph go from the trunks?
Into lymphatic ducts
Which duct drains the right upper arm, right side of head and thorax?
the right lymphatic duct
Which duct drain the rest of the body?
Thoracic duct
What is lymphangitis?
Condition in which lymphatic vessels appear as painful red lines under the skin
What causes lymphangitis?
Inflammation of larger lymphatic vessels that contain vaso vasora
To what antigens protect T cells and B cells?
Bacteria and their toxins; viruses
Mismatched RBCs or cancer cells
What is the function of T cells?
Manage the immune response
Attack and destroy foreign cells
What is the function of B cells?
Produce plasma cells, which secrete antibodies
What are other lymphoid cells?
Macrophages, Dendritic cells, reticular cells
What are the functions of macrophages, dendritic cells and reticular cells?
Macrophages foreign substances and help activate T cells
Dendritic cells capture antigens and deliver them to lymph node
Reticular cells produce stroma that supports other cells in lymphoid organs
What is another name for dendritic cells?
Antigen-Presenting-Cells (APCs)
Which lymph tissue dominates?
Reticular except for the thymus
Which two main lymph type tissues are there?
Diffuse lymphoid tissue and lymphoid follicles
Why is lymphoid tissue an important component of the immune system?
Houses and provides a proliferation site for lymphocytes
Furnishes a surveillance vantage point for lymphocytes and macrophages
How does diffuse lymphatic tissue look like?
Scattered reticular connective tissue elements
What does lymphatic follicles look like?
Solid, spherical bodies of tightly packed reticular elements and lymphoid cells
Where are lymph nodes for?
they have protective functions as filters lymph and in the immune system lymphocytes are activated
What is the global structure of a lymph node?
Bean shaped, external fibrous capsule, trabeculae extend inward and divide the node into compartments, cortex and medulla
What is Bubo?
An inflamed lymph node
What is the effect of fewer efferent vessels?
Causes flow of lymph to stagnate, allowing lymphocytes and macrophages time to carry out functions
What does afferent mean?
To the organ
Which other organs contribute to lymphatic function?
Spleen, MALT (Mucosa-associated tissues, tonsils, Peyer’s patches, appendix, thymus)
What are the functions of the spleen?
Cleanses the blood of aged cells and platelets
recycles the breakdown products of RBCs for later reuse
Stores blood platelets and monocytes
RBC production in fetus
What is the function of the MALT?
Trap and remove bacteria and other foreign material in tonsillar crypts
What is the function of the thymus?
Organ where T cells mature
