The Lymphatic System Flashcards
the lymphatic system consists of
a network of lymphoid tissues and lymphatic vessels that drain excess fluids that seeped out of the blood into the tissue spaces
lymphatic vessels absorb
lipids and lipid-soluble vitamins from gastrointestinal tract and transport them to the blood
lymphoid tissues protect against
foreign cells, microbes, toxins, and cancer cells
lymph is a
relatively clear, colorless fluid that is similar to blood plasma but it contains fewer proteins and its composition varies throughout the body
interstitial lymph is
milky white following a meal because of its high fat content
lymph in a lymph node may be filled with
lymphocytes, macrophages, and debris
lymphatic capillaries are
microscopic vessels, which are located everywhere in the body except in avascular tissues
lymphatic capillaries are slightly _____ than blood capillaries but,
larger
but have closed ends
endothelial cells overlap one another and act as
valve-like flaps
interstitial fluid flow
can flow into lymphatic capillary when fluid pressure in tissues is high but can’t flow out when fluid pressure in tissues is low
small intestine contains
specialized lacteals to transport dietary lipids
lymphatic capillaries unite to form
lymphatic vessels, which may pass through lymph nodes
lymphatic vessels resemble veins but
they have thinner walls and more valves
lymphatic vessels unite to form
lymphatic trucks , which drain different parts of the body
lymphatic trunks converge to form
lymphatic ducts, which return fluid to the blood
thoracic duct drains
left side of head, neck, chest, left arm, and entire body below the ribs into left subclavian vein
right lymphatic duct drains
lymph from upper right region of body into right subclavian vein
lymph flows slowly though the lymphatic system and is controlled mainly by
contractions of skeletal muscles and respiratory movements
lymphatic cells can be
loosely scattered in mucous membranes, or tightly clustered and encapsulated in lymphatic organs
T lymphocytes develop in
the thymus and carry out immune responses
B lymphocytes mature in
bone marrow and produce antibodies to protect the body against disease causing organisms or substances
macrophages phagocytize foreign antigens and become
antigen-presenting cells (APC)
dendritic cells and reticular cells are
antigen presenting cells in the lymphatic organs
lymphatic cells form
dense lymphatic nodules in lymph nodes and the tonsils, and form Peyer’s patches in the small intestine
lymph nodes are
bean shaped structure located along lymphatic vessels, especially in the mammary glands, in the armpit region, and in the groin
a lymph node is covered by
a fibrous capsule that extends inward and divides the node into compartments
interior of a lymph node consists of
a stroma and parenchyma, which contains lymphocytes and antigen presenting cells
outer cortex of parenchyma contains
germinal centers where B lymphocytes multiply
inner medullar of parenchyma contains
B lymphocytes, macrophages, and reticular cells
lymph flows into a lymph node through
afferent lymphatic vessels, then passes through sinuses, and finally exits the lymph node by way of an efferent lymphatic vessel
lymph nodes filter and cleanse lymph as it flows toward
the blood stream
macrophages and reticular cells remove
most impurities and foreign substances by a variety of immune responses
viruses can infect
lymph nodes and cerate reservoir of viral particles that escape detection by immune system
cancer cells traveling through the lymphatic system may form
secondary tumors when they lodge in lymph nodes
cancer cells can establish
new growths in a lymph node, block flow of lymph and causes swelling
cancerous lymph nodes are
swollen, but seldom painful
tonsils are
concentrations of lymphoid tissue at the entrance to the pharynx and they guard against ingested and/or inhaled pathogens
one pharyngeal tonsil (adenoid), pair of palatine tonsils, and a pair of lingual tonsils are located
at the base of tongue
a tonsillectomy removes
the palatine tonsils if they are chronically infected
the thymus gland is located in the
mediastinum posterior to the sternum and its two lobes are surrounded by a fibrous capsule that divides each lobe into several lobules
each lobule of the thymus gland consists of
an outer cortex and an inner medulla
cortex contains
lymphocytes, reticular epithelial cells, and macrophages
medulla contains
mostly reticular epithelial cells and thymic corpuscles
reticular epithelial cells secrete
thymic hormones that cause T lymphocytes to mature and migrate to lymph nodes, spleen, other lymphoid tissues
thymus gland is very large in
an infant and grows even larger during childhood
after puberty thymic tissue is
replaced by adipose and areolar connective tissue until thymus gland is barely distinguishable in an adult
the spleen is
the largest lymphatic organ and contains different kinds of lymphoid tissue
white pulp contains
lymphocytes and macrophages and plays role in immunity
red pulp consists of
venous sinuses filled with red blood vells
spleen produces
red blood cells in a fetus
macrophages remove
worn out or damaged erythrocytes and defective platelets and phagocytize them to replace*** hemoglobin
abdominal trauma can
rupture the spleen and cause severe internal bleeding which cannot be stopped unless spleen is removed by splenectomy
if the spleen fails the ________________ can take over some functions of the spleen
red bone marrow and the liver
edema
the accumulation of excess fluid in a tissue, either because of capillary filtration exceeds capillary reabsorption or because lymphatic vessels become obstructed
elephantiasis is causes by
a roundworm transmitted via mosquitoes which blocks the flow of lymph and produces chronic edema
lymphadenopathy describes
enlarged, tender lymph nodes
lymphomas are
lymphatic cancers that usually orginate in isolated lymph nodes
Hodgkin’s disease is characterized by
swollen, painless lymph nodes and alternating fever and night sweats, one of the most common cancers among young adults
non-Hodgkin’s lymphomas result from
uncontrolled multiplication of lymphocytes that metastasize, which might be cause by a virus
treatments for Hodgkin’s lymphomas
chemotherapy and radiation are used to induce cure
non-Hodgkin’s lymphomas is characterized by
swollen lymph nodes or swelling in the spleen and Peyer’s patches
non-Hodgkin’s lymphomas treatment
usually responds to chemotherapy
