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72 terms

Anatomy 2-Lymphatic System Ch20

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2 main functions
maintaining fluid balance & immunity
minor functions
collect absorbed fat from the intestines and transport it to the systemic veins
lymph
watery fluid drained from the tissue spaces that returns excess fluid and protein molecules to the blood via the lymphatic vessels
lymphatic fluid
found in lymphatic vessels, has elevated protein concentration in thoracic duct because protein-rich lymph from liver/small intestine drains into thoracic duct
interstitial fluid
fluid that fills the spaces bt the cells of a tissue; along with blood plasma, constitutes extracellular fluid
both interstitial fluid & lymph
clear isotonic fluids, have similar composition to blood plasma and to each other, have lower protein concentration than blood plasma
lymphatic capillaries
microscopic blind-end vessels, walls consists of a single layer of flattened endothelial cells; networks branch and anastomose freely
lymphatic capillaries
merge to form larger lymphatics and eventually form the main lymphatic trunks, R lymphatic ducts, and thoracic duct
lymph from upper right quadrant
empties into R lymphatic duct and then into R subclavian vein
lymph from body
empties into thoracic duct, which then drains into the L subclavian vein
chyle cistern
aka cisterna chyli, what the thoracic duct originates from
structure of lymphatic vessels
similar to veins except they have thinner walls, many more valves, & contain lymph nodes
lymphatic capillary wall
formed by single layer of endothelial cells
diameter of lymphatic vessels increase
from capillary size, walls become thicker, have 3 layers
function of lymphatic vessels
remove high molecular weight substances and particulate matter from interstitial fluid
function of lymphatic vessels
lacteals absorbs fats and other nutrients from small intestine, transport through lymphatics to circulation
movement of lymph
flows through larger lymphatic vessels to reenter blood at junction of the internal jugular and subclavian veins
interstitial pressure
influences flow of lymph
large lymphatic trunks in thorax
have small amount of smooth muscle, pulses rythmically to assist in return of lymph
lymphokinesis
the movement of lymph; can be visualized in a lymphangiogram
lymphatic pump
moves through system in correct direction because of many valves
establish fluid pressure gradient
breathing movement & skeletal muscle contractions, as with venous blood
lymphkinetic actions
activities that result in a central flow of lymph (massage, exercise)
structure of lymph nodes
oval-shaped structures enclosed by fibrous capsules; biological filter
trabeculae
aspect of lymph nodes; extend from covering capsule toward center of the node
reticuloendothelial cells
line the cortical and medullary sinuses; capable of phagocytosis
Lymph nodes
occur in groups, small structures that performs biological filtration of lymph on its way to the circulatory system
important lymph nodes
preauricular, submental and submaxillary, superficial cervical, superficial cubital, axillary, iliac, inguinal
surveillance
lymph node defense
filtration
lymph node defense; mechanical & biological filtration
mechanical filtration
physically stopping particles from progressing further in the body
biological filtration
biologic activity of cells destroys and removes particles by phagocytosis
lymphoid tissue
site of final maturation of most lymphocytes and monocytes
lymph nodes in disease
lymph nodes downstream from site of infection become swollen due to the recruitment of lymphocytes
lymph nodes role in cancer
cancer cells metastasize, break separate from primary tumor and travel through the lymphatics to other parts of the body
lymph nodes role in cancer
cancer cells may become lodged in lymph nodes forming a metastasis and may ultimately block lymph drainage from that region causing swelling
lymphedema
swelling of lymph nodes due to infection/cancer
lymphedema causes
caused by: parasitic worms (elephantiasis), congenital malformation of lymphatics, lymphangitis, tonsillitis, lymphoma, surgical removal of lymph nodes
lymphoma
cancer of lymph nodes
lymphatic drainage of the breast
clinically important because cancer cells and infections can spread along lymphatic pathways to lymph nodes and other organs of the body
2 sets of lymphatic tissue in breast
1.drain the skin over breast with exception of areola/nipple 2.drain the underlying substance of breast, as well as skin of areola/nipple; connected to fascia of pectoralis major muscles
cutaneous lymphatic plexus
collection of lymphatic tissue that drains over breast with exception of areola/nipple
subareolar plexus
aka Plexus of Sappey; communication between 2 sets of tissue of breast occurs here
plexus
intricate network or web-like formation
85% of lymph tissue of breast
enters the lymph nodes of axillary region; the remainder enters along lateral edges of the sternum
tonsils
form a discontinuous ring under the mucous membranes in themouth and back of the throat aka pharyngeal lymphoid ring
palatine tonsils
located on each side of throat
pharyngeal tonsils
located near the posterior opening of nasal cavity
lingual tonsils
located near base of tongue
tubal tonsils
located near the openings of the auditory (eustachian tubes)
tonsils
protect against bacteria that may invade tissues around the openings bt nasal and oral cavities; bacteria trapped in tonsillar crypts and put in close contact with immune system cells
thymus
primary central organ of lymphatic system; single, unpaired organ located in mediastinum extending upward to lower edge of thyroid and inferiorly as far as 4th costal cartilage
thymus color in childhood
pinkish gray
thymus color in adulthood
yellowish, as lymphoid tissue is replaced with fat; also shrinks with age
thymus structure
pyramid shaped lobes, subdivided into smaller lobules
thymus lobule
composed of dense cellular cortex and inner, less dense medulla
thymic corpuscles
identifies medullary tissue
spleen location
L hypochondrium, directly beneath diaphragm, above L kidney and descending colon and behind fundus of stomach
spleen structure
ovoid shape, surrounded by fibrous capsule with inward extensions that divide organ into compartments
white pulp
part of spleen; dense masses of developing lymphocytes
red pulp
part of spleen; near outer regions, composed of network of reticular fibers submerged in blood that comes from nearby arterioles; composed of cords of WBCs and related cells surrounded by sinusoids
spleen function
defense; macrophages lining sinusoids of spleen remove microorganisms from blood and phagocytose them
spleen function
hematopoiesis; monocytes and lymphocytes complete their development
spleen function
RBC/platelet destruction;macrophages remove worn out RBCs and imperfect platelets and phagocytose them. Salvage iron/globin from RBCs
spleen function
blood reservoir; pulp of spleen and its sinuses store blood
Unique spleen
none of functions unique to spleen, therefore it can be removed without dire consequences
Lymphatic system overview
drains away excess H2O from large areas, lymph conducted through lymphatic vessels to nodes where contaminants are removed, benefits whole body by maintaining fluid balance and freedom from disease
interstitial fluid
complex, organized fluid that fills the spaces bt the cells and is part of the ECM; resembles blood plasma in composition with a lower % of protein
interstitial fluid, blood plasma
_______ ________ and _____ _______ constitutes the extracellular fluid
mechanical filtration
physically stopping particles from progressing further in the body
biological filtration
biological activity of cells destroys and removes particles
thymus functions
plays role in immunity, source of lymphocytes before birth, shortly after birth it secretes thymosin/other regulators which enables lymphocytes to develop into T cells