Chapter 21 - Lymphatic System Flashcards
Lymphatic System Components
Lymphatic vessels & lymph
Lymphatic vessels include
Lymph capillaries -> lymphatic collecting vessels -> lymph trunks -> lymph ducts
It is a one-way system, only TOWARD the heart
lymph
fluid from loose CT that surrounds tissue
more fluid exits from the arteriole side than leaves from the venule side
lymph capillaries
collect the excess tissue fluid
single layer of endothelium
drains into lymphatic collecting vessels
located at most places blood capillaries occur EXCEPT bone, teeth, bone marrow, and CNS
Specialized ones in small intestine called lacteals
lacteals
specialized for fat absorption
chyle
fatty lymph
lymph collecting vessels
carry fluid to nodes, which filter and purify
have same 3 tunics as blood vessels and contain valves
superficial vessels travel with veins; deep vessels travel with arteries
have many valves
Movement of lymph is propelled by
skeletal muscle action
artery pulsations
tunic media
normal movements of trunk and limbs
Lymph nodes
remove pathogens from lymph
bean-shaped, often occur in clusters
If cancer gets into lymphatic system, the cells can be widely dispersed and tumors can develop at nodes
Microscopic anatomy of the node
Surrounded by fibrous capsule (dense CT) Trabeculae extend inward Afferent and efferent lymphatic vessels Hilus Lymph sinuses are located between afferent and efferent vessels Follicles (nodules)
Hilus
indented region in lymph nodes (efferent exit through)
Macrophages
consume foreign particles
Follicles (nodules)
masses of lymphoid tissue
Lymph Trunks
Formed by convergence of largest lymphatic collecting vessels
Drain large areas of the body
What are the large areas of the body that lymph trunks drain
lumbar trunks intestinal trunk bronchomediastinal trunks subclavian trunks jugular trunks
lumbar trunks
drain lower limbs, pelvic organs, anterior abdominal wall
intestinal trunks
drains stomach, intestines, digestive organs
bronchomediastinal trunks
drain thoracic viscera/wall
Subclavian trunks
drain upper limbs, inferior neck, superior thoracic wall
Jugular trunks
drain head and neck
Lymph ducts (2)
largest lymphatic vessels
Thoracic duct
Right lymphatic duct
Thoracic duct
runs along vertebral bodies
empties into veins at intersection of left internal jugular and left subclavian veins
Sometimes is joined by other lymph trunks
Right lymphatic duct
Found in `20% of people
Union of right jugular, subclavian, and bronchomediastinal trunks
Drains near junction of right internal jugular and subclavian veins (right upper 1/4 of the body)
If not present, trunks drain into separate veins
Immune System Key components
lymphocytes
lymphoid tissue
lymphoid organs
Immune system Function
fight disease/antigens
antigen
foreign molecule
Lymphocytes
WBCs that recognize and attack specific types of foreign molecules
Mocroorganism penetrates epithelial barriers, attacks underlying CT - is in turn attacked by inflammation, macrophages, and lymphocytes
Recirculation
B and T cells continuously circulate, enter/exit CT, lymph tissue, blood vessels
Lymphocyte Activation in order
Lymphoid stem cells
Thymus (T cells) OR stay in bone marrow (B cells)
rapid regeneration & formation of lymphocyte families (specific to antigens)
cells become fully mature when they attack antigen and they divide to form more that attack the same antigen
antigen presenting cell
“presents” antigen to lymphocyte
b cells in lymphocyte activation
mark antigens for phagocytosis
T cells in lymphocyte activation
Either directly lyse cells (cytotoxic) or release cytokines (helper), which stimulate production of deferent cell types
memory lymphocyte
waits in lymphoid tissue in case antigen comes back later
Lymphoid tissue
specialized CT that has many lymphocytes
main “battleground” for infection
lymphocyte activation site
framework is reticular CT with fibroblasts
Lymphoid tissue locations (2)
MALT
All lymphoid organs except thymus
MALT
mucosa-associated lymphoid tissue
frequently affected mucous membranes located in digestive, respiratory, urinary, and reproductive tracts
lymphoid follicles (nodules)
clusters of lymphocytes - each comes from a single B cell that rapidly divides (new ones leave to become plasma cells
Lymphoid organs (2 catagories)
primary lymphoid organs
secondary lymphoid organs
Primary lymphoid organs
Bone marrow (B cells) Thymus (T cells)
Secondary lymphoid organs
Lymph nodes
spleen
tonsils
lymphoid nodules (gather infectious microorganisms)
Bone marrow
Red marrow generates blood cells
B cells develop immunocompetence in bone marrow and travel to secondary lymphoid organs
Lymphocytes are fully activated at antigen challenge
Mature lymphocytes continuously circulate
Thymus
Superior thorax, posterior to sternum lymphocytes develop into T cells Thymic hormones cause T lymphocytes to gain immunocompetence Atrophies over time Does not directly fight antigens Not composed of lymphoid CT
Lymph nodes
Lymphatic and immune systems overlap
lymphoid tissue destroys antigens and activates T and B cells
Spleen
Largest lymphoid organ
left superior quadrant of abdominal cavity, posterior to stomach
Removes antigens and worn out blood cells, store platelets
Tonsils (4 groups)
Swellings of mucosal linings of pharynx Palatine (largest and removed in tonsillectomy) Lingual Pharyngeal Tubal
Aggregated lymphoid nodules
Clusters of lymphoid follicles in ileum (distal part) of small intestine
Appendix
Offshoot of cecum (1st part) of large intestine
Disorders of Lymphatic/Immune System
Mononuleosis
Hodgkin’s disease
Mononucleosis
Viral disease
Fatigue, fever, sore throat, swollen lymph nodes
Epstein-Barr virus (attacks B cells)
Transmitted via saliva, lasts 4-6 weeks
Hodgkin’s disease
Malignant lymph nodes
Fatigue, swollen/painful nodes, fever, night sweats
Treated with radiation and has high cure rate relative to other cancers
