packet 8 Flashcards
lymphatic system includes
organs, vessels, and lymph
Organs involved in lymph system
red bone marrow thymus spleen lymph nodes lymphatic tissue
Capillaries that begin asclosed-ended tubes foundin spaces between cells
Combine to form lymphaticvessels
resemble veins with thinwalls & more valves
Fluid flows through lymph nodes towards large veins above the heart
lymph emptied into bloodstream
lymphatic vessels and circulation
Found throughout thebody except in Avascular tissue (cartilage, epidermis& cornea)
Structure is designed to lettissue fluid in but not out
anchoring filaments keep tubefrom collapsing under outside pressure
overlapping endothelial cells open when tissue pressure is high (one-way valve)
lymphatic capillaries
Vessels unite to form trunks & thoracic ducts
Right side head, arm & chest empty into right lymphatic duct and rest of body empties into thoracic duct
Lymph is dumped directly into left & right subclavian veins
Lymph Trunks & Ducts
Fluid & proteins escaping from vascular capillaries is collected by lymphatic capillaries & returned to the blood
Respiratory & muscular pumps promote flow of lymphatic fluid
Lymphatic vessels empty into subclavian veins
formation and flow of lymph
Draining excess interstitial fluid & plasma proteins from tissue spaces
Transporting dietary lipids & vitamins from GI tract to the blood
Facilitating immune responses
recognize microbes or abnormal cells & responding by killing them directly or secreting antibodies that cause their destruction
functions of lymphatic system
provide environment for stem cells to divide & mature into B and T lymphocytes
red bone marrow gives rise to mature B cells
thymus is site where pre-T cells from red marrow mature
primary lymphatic organs
site where most immune responses occur
lymph nodes, spleen & lymphatic nodules
Secondary lymphatic organs & tissues
tightly packed lymphocytes ¯ophages
cortex
reticular epithelial cells produces thymic hormones
Hassall’s corpuscles
medulla
Large organ in infants (70 g) but atrophied as adult (3 g)
2 lobed organ located in mediastinum
Capsule & trabeculae divideit into lobules
Each lobule has cortex &medulla
Cortex
medulla
thymus gland
Flow is in one direction
afferent vessels lead in
sinuses lead to efferent vessels that exit at hilus
Only nodes filter lymph
lymph nodes
Parenchyma is divided into 2 regions:
cortex and medulla
lymphatic nodules with germinal centers containing dendritic cells
antigen-presenting cells and macrophages
B cells proliferate into antibody-secreting plasma cells
cortex
contains B cells & plasma cells in medullary cords
medulla
Bean-shaped organs, up to 1 inch long, located along lymphatic vessels
scattered throughout body but concentrated near mammary glands, axillae & groin
Stroma is capsule, trabeculae & reticular fibers
Parenchyma
lymph nodes
Characteristic of malignant tumors
Spread of disease from one organ to another
cancer cells travel via blood or lymphatic system
cells establish new tumors where lodge
Secondary tumor sites can be predicted by direction of lymphatic flow from primary site
Cancerous lymph nodes are firm, enlarged and nontender – infected lymph nodes are not firm and are very tender
Metastasis Through Lymphatic System
Concentrations of lymphatic tissue not surrounded by a capsule scattered throughout connective tissue of mucous membranes mucosa-associated lymphoid tissue (MALT) Peyer’s patches in the ileum of the small intestine Appendix Tonsils form ring at top of throat adenoids (pharyngeal tonsil) palatine tonsils (on each side wall) lingual tonsil in the back of the tongue
lymphatic nodules
venous sinuses filled with blood & splenic tissue (splenic cords
red pulp
lymphatic tissue (lymphocytes & macrophages) around branches of splenic artery
white pulp
Parenchyma consists of
white pulp and red pulp
5 inch organ between stomach & diaphragm
Hilus contains blood & lymphatic vessels
Stroma consists of capsule, trabeculae, fibers & fibroblasts
Parenchyma
spleen
connective tissue that hold vessels in place and hold small organs in place
hilus
