Chapter 9- Lymphoid system Flashcards
the major function of the lymphatic system is to provide a source of ____ cells that react with and neutralize antigens
immunocompetent
System comprises of lymphoid _____ and ____ whose main constituents are aggregates of ____ and other cells of the phagocyte system
tissues, organs, lymphocytes
two different arrangements of the lymph include:
MALT and nodules
Nodules may appear as single collections of lymphocytes or as more permanent, multiple aggregates such as ___ and ____ ___.
tonsils, Peyer Patches
major sites of lymphocyte production and maturation, includes bone marrow where B lymphocytes are produced, and the Thymus where T lymphocytes mature are known as
primary lymphatic organs
the lymph nodes and the spleen are examples of ___ lymphatic organs
secondary
cells of the lymphoid system have the ability to travel through the ____
bloodstream
thin walled lymphatic capillaries that anastomose and become larger are known as
lymphatic vessels
___ ____ are most abundant in connective tissue of the skin (dermis), beneath mucous membranes of the respiratory, GI, and GU tracts and in connective tissue spaces of the liver
lymphatic capillaries
Like veins, lymphatic vessels have ___ and __ ___
valves, thin walls
MALT may be subdivided on the basis of location into: GALT: ___ associated BALT: ____ associated NALT: ___ associated VALT: ______ associated
gut, bronchus, nose, vulvovaginal
primary lymphoid nodules contain small, ___ _ ____
immature B lymphocytes
In response to ____ _____, primary nodules become secondary nodules, which contain pale stained germinal centers
antigen exposure
these occur, often as chains or groups, in strategic regions such as the neck, groin, mesenteries, axillae, and abdomen
lymph nodes
three main functions of lymph nodes include: ___ of lymph, synthesis of ____, and _____ of lymphocytes that are added to lymph
filtration, antibodies, production
____ ____ of dense fibrous connective tissue that typically merges with surrounding tissues and fat invests each node
outer capsule
beam-like structures of collagen fibers called ___ provide support and serve as conduits for blood vessels in the nodes
trabeculae
secondary nodules, which have a ____ ____ surrounded by a mantle zone which contains small lymphocytes
germinal center
germinal centers of secondary nodules are major sites of __ ___ proliferation
B cell
Antigen-dependent T cell differentiation and proliferation occur in the _____, beneath and between nodules
paracortex
the ____ contains irregular strands of loosely arranged lymphoid tissue, the medullary cords, which consist mainly of lymphocytes, macrophages, and plasma cells
medulla
Lymph enters the nodes via _____ lymphatics
afferent
___ in efferent lymphatics force lymph to flow out
valves
_____ phagocytose antigens and foreign material, thus filtering lymph
Macrophages
Lymphocytes leave the bloodstream by preferential migration across the walls of specialized blood vessels called ___ ____ ___
high endothelial venules
HEV’s are found in the ___ of a lymph node
paracortex
movement of B and T cells across HEVs into lymph nodes and other sites is called ____, and it is determined by specific ___ ___ molecules
homing, cell adhesion
HEVs include ___ endothelial cells and a thick basal lamina
cuboidal
the spleen lacks ___, but has similar structures to make up for it
HEVs
discrete aggregates of lymphoid nodules under the epithelium lining entrances to the digestive and respiratory tracts are known as
tonsils
a pair of ___ tonsils lie in the wall of the oropharynx
palatine
at the base of the tongue sit two ___ tonsils
lingual
at the posterior portion of the nasopharynx sits the ___ tonsil
pharyngeal
the tonsils of the mouth region form a broken ring of strategically placed lymphoid tissue known as the ___ ___
Waldeyer ring
major role of the tonsils is defense against bacterial and viral infections via production of ______ by __-cell derived plasma cells
immunoglobulins, B
a common condition seen in children including hypertrophy and chronic inflammation of the pharyngeal tonsils is known as
adenoiditis
tonsillitis results from infection of the bacteria _____
Streptococcus
palatine tonsils are covered by ____ ____ ____ epithelium and heavily infiltrated by lymphocytes
nonkeratinized stratified squamous
surface epithelium forms ___ ___ which increase surface area and enhance interactions of antigens with underlying immunocompetent cells
tonsillar crypts
tonsils have ___ glands associated with them with ducts to drain at the surface or into crypts
mucous
tonsils become enlarged or infected when ____ become clogged or obstructed by secretions from mucous glands
crypts
the external surface of the pharyngeal tonsil is covered by ____ epithelium
pseudostratified
the flat, bilobed primary lymphoid organ found in the anterior mediastinum of the thorax is known as the ____
thymus
after puberty, the thymus begins the process of ___, replacing its lymphoid parenchyma with ____ ____ tissue
atrophy, adipose connective
the ____ of the thymus contains densely packed small lymphocytes
cortex
main function of the thymus is the ____ of _ lymphocytes
maturation, T
supportive framework or stroma of the thymus are known as ___ ___ cells
epithelial reticular
as T-cells from the thymus mature, they are discharged into ____ to go to secondary lymphoid ___ & ____.
circulation, tissues, organs
two hormones secreted by ERC’s are ___ and ___ which induce T cell maturation
thymosin, thymopoietin
blood vessels enter and exit the thymus via ____
trabeculae
lymphocytes from the ___ will divide often, migrate to the ___, and eventually exit the organ
cortex, medulla
the ERC’s of the thymus help form the ___-___ barrier found in the cortex
blood thymus
the ____ ____ of the thymus medulla release thymic stromal thymopoeitin to induce CD4+ regulatory T cell development
Hassall corpuscles
this lymphatic organ lies in the upper left quadrant of the abdomen behind the stomach and just below the diaphragm
spleen
at the ___ of the spleen, the splenic artery and nerves enter the organ, while the splenic veins and lymphatics leave
hilum
during early fetal development, the spleen has a role in _____, which is then taken over by the liver and bone marrow
hematopoiesis
the spleen also holds ___ of the body’s platelets, and accounts for ___% of the total number of lymphocytes
1/3, 25
the main function of the organ is to __ ___, removing particulate matter, infectious organisms, and aged or defective erythrocytes
filter blood
the spleen can also produce ___, ___ cells, __ & ___.
lymphocytes, plasma, IgM, IgG
spleen covered by an outer __ ___ capsule, and includes a communicating network of ____ fibers
dense irregular, reticular
instead of a cortex and medulla, the spleen includes ___ & ____ ____.
red, white, pulp
___ pulp is made of grayish white islands of lymphoid tissue, surrounding a central arteriole.
white
the ____ ___ surrounds the white pulp and contains many macrophages with occasional B lymphocytes
marginal zone
____ pulp makes up most of the spleen with its color coming from abundant erythrocytes
red
red pulp contains ___ ____, where reticular cells, plasma cells, macrophages, and formed elements of circulating blood can be found
venous sinusoids
trabecular arteries branching off the splenic artery enter the ____ pulp and become ____
white, arterioles
other arterial branches enter the red pulp as ____ arterioles
pencillar
