Lymphatic System (For Exam #3) Flashcards
What are the functions of the lymphatic system?
move lymph and help the body fight infection
How many liters of fluid per day do not make its way back into venous return?
3 L
Lymph vessels _________ excess fluid and return it to venous circulation.
reabsorb
Edema is the result of poor…
reabsorption of fluid
Lymph vessels around the GI tract also transport ________ through lacteals.
dietary lipids
Lymphatic capillaries _______ fluid with one-way valve system formed by overlapping cells.
“trap”
Lymphatic capillaries merge to form…
lymphatic vessels
How are lymphatic vessels similar to veins?
- have 3 tunics (intima, media, externa)
- have valves to prevent backflow
_______ lymphatic vessels bring lymph to a node (which filters lymph) and _______ vessels carry it away
afferent ; efferent
What is included in lymph?
interstitial fluid, solutes, dietary lipids
Lymph vessels can be found anywhere except…
bone
bone marrow
teeth
central nervous system
Lymphatic trunks form from….
merging lymphatic vessels
What do lymphatic trunks do?
drain lymph from major regions of the body
Jugular trunks drain lymph from…
head and neck
Subclavian trunks drain lymph from…
upper extremities
breasts
thoracic wall
Bronchomediastinal trunks drain lymph from…
deep thoracic structures
The intestinal trunk drains lymph from…
most abdominal structures
Lumbar trunks drain lymph from…
lower extremities and pelvis
Absorption of fat makes the lymph what color?
milky white (is originally clear)
What are the largest of the lymphatic vessels?
the lymphatic ducts
The right lymphatic duct drains lymph from the…
right upper extremity
right side of head
neck
thorax
The thoracic duct drains lymph from…
abdomen pelvis lower extremities left upper extremity left side of head and neck
Where does the right lymphatic duct empty?
at the junction of the right subclavian vein and left internal jugular vein
Where does the throacic duct empty?
at the junction of the left suclavian vein and left internal jugular vein
Cysterna Chyli
saclike structure that receives a milky lymphatic fluid (chyle) from the small intestine
- is continuous superiorly with the thoracic duct; is the origin of the thoracic duct
Where are lymphatic cells found?
lymphatic system
cardiovascular system
Function of the lymphatic cells
elicit an immune response
Macrophages
monocytes that have migratedinto the lymphatic system from bloodstream
- responsible for phagocytosis of foreign substances
Dendritic Cells
- located in lymphatic nodules (cluster of lymphatic cells)
- internalize antigens from lymph and present them to other lymphatic cells
Lymphocytes
- most abundant cells in the lymphatic system
- 3 types: T-lymphocytes, B-lymphocytes, natural killer cells
T-Lymphocytes (T-Cells)
- account for 70-85% of all lymphocytes
- have surface receptors for specific antigens
- main types are helper T-lymphocytes, cytotoxic T-lymphocytes, and memory T-lymphocytes
Helper T-Lymphocytes
- needed to being a defense against an antigen
- contain the CD4 coreceptor (CD4+cells, or T4 cells)
- each helper T-lymphocyte is activated by one type of antigen (virus, bacterium, etc.)
- release cytokines to activate other lymphatic cells
Cytotoxic T-lymphocytes
- contain the CD8 receptor (CD8+ cells, or T8 cells)
- come in direct contact with infected or foreign cells and kill them
- responds to specific antigen
Memory T-Lymphocytes
- arise form T-lymphocytes that have encountered a foreign antigen
- provide augmented response to exposure to the specific antigen
B-Lymphocytes
- account for 15-30% of all lymphocytes
- have surface receptors for specific antigens
- activated by helper T-lymphocyte, they divide and differentiate into plasma cells and memory B-lymphocytes
- plasma cells secrete immunoglobulins, or antibodies, which attach to antigens
- antibody-antigen complexes are then eliminated
- memory B-lymphocytes provide enhanced response to subsequent exposure to antigen
Natural Killer (NK) Cells
- make up remaining percentage of lymphocytes
- can kill a wide variety of infected cells
Lymphopoiesis
- the process of lymphocyte development and maturation
- all lymphocytes originate in red bone marrow, but their maturation sites differ
Lymphatic Nodules
- clusters of lymphatic cells (B-cells, T-cells, macrophages)
- filter and attack antigens
Mucosa-Associated Lymphatic Tissue (MALT)
large collections of lymphatic nodules in the mucosa of digestive, respiratory, and urinary tracts
Tonsils
large clusters of lymphatic cells surrounded by connective tissue capsule
- palatine, pharyngeal, and lingual
What are the lymphatic organs?
thymus, lymph nodes, spleen
What are lymphatic organs?
lymphatic cells within an extracellular connective tissue matrix, completely surrounded by connective tissue capsule
Where do B-lymphocytes and natural killer cells differentiate and mature?
red bone marrow
Where do T-lymphocytes differentiate and mature?
thymus
- occurs during childhood
What part of the thymus contains immature T-lymphocytes, nurse cells, and macrophages?
cortex
What part of the thymus contains mature T-lymphocytes and some epithelial cells?
medulla
Thymic Corpuscles
areas of degenerated nurse cells in the medulla
Is the thymus usually present in adults?
no
Lymph nodes are found along…
lymph vessels
Spleen
- largest lymphoid organ in the body
- surrounded by a capsule
- divided into red and white pulp
White Pulp
circular clusters of lymphatic cells
- monitor BLOOD for foreign materials, bacteria, and other antigens
Red Pulp
contains extra supply of erythrocytes and platelets in case they are needed for the body
Lymphedema
accumulation of excess fluid in the interstitial spaces
- can be due to lack of venous return due to varicose veins, DVT, or blockage/surgical removal of lymph collecting vessels
What are the functions of the spleen?
- immunosurveillance (white pulp)
- red blood cell inspection (red pulp)
What do the epithelial reticular cells in the thymus do?
- isolate capillaries in the thymus to form a blood-thymus barrier that protects developing T-cells from premature stimulation by antigens
- produce thymic hormones (thymosin, thymopoietin)
- destroys T-cells that recognize self
Where are palatine tonsils?
lateral sides on the pharyngeal wall
- they are the largest and most likely to be removed in childhood due to infection
Where are the lingual tonsils?
posterior surface of the tongue
Where are the pharyngeal tonsils (adenoids)?
on the pharyngeal roof
Where are the tubal tonsils?
just behind the opening of the pharyngotympanic tubes into the pharynx
Primary Immune Response
- mediated by both T-cells and B-cells
- activation is relatively slow
- when activated, T and B-cells proliferate, mature, and function as effector cells, then die
- some activated cells remain as memory cells
Secondary Immune Response
subsequent challenge by the same antigen results in a quicker and more robust (stronger) response
- speed and strength is due to memory cells
What cells are affected by HIV/AIDS?
the helper cells
- prevents body from triggering an immune response since body cannot regulate population of B-cells and cytotoxic T-cells
What is the purpose of the thorax?
protect thoracic viscera
What is the thoracic cage composed of?
sternum
12 thoracic vertebrae
12 ribs (7 true, 5 false)
What is contained in the thorax?
lungs heart great vessels esophagus inferior vena cava descending aorta vagus and phrenic nerves
Where does the descending aorta pass through the thorax?
behind the diaphragm at level T12
Where does the esophagus pass through the thorax?
T10
Where does the inferior vena cava pass through the thorax?
T8
