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151 Cards in this Set

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  • Back
What is the lymphatic system?
A closed system of lymphatic vessels with associated lymphatic organs
What are some examples of lymphatic organs?
lymph nodes
spleen
thymus
tonsils
What are three functions of the lymphatic system?
1. returns to the blood the fluid and plasma protein that escape from the circulation.
2. returns to the blood the lymphocytes of the recirculating pool
3. adds to the blood antibodies that are formed in the lymph nodes
What type of tissue are all lymphoid organs made of?
lymphatic/lymphoid or adenoid tissue
What type of tissue is the back bone for all lymph tissue?
reticular connective tissue
What is a general definition of lymphatic tissue/adenoid tissue?
has a connective tissue backbone in which various cells are suspended
What do reticular cells form?
reticular CT
What do reticular cells look like?
-star shape w/ cell processes= stellate in shape
-cytoplasm is weakly basophilic
-has a large pale staining nucelus
What is the reticular cell "fishnet framework"
-knots of the net are the cell bodies
-strings are the cell processes
-there are numerous holes formed in between the strings where other cells are found
What holds reticular cell processes together within the CT framework?
-reticular fibers
-they are not held together by junctional specializations such as desmosomes
What is the most numerous cell present in lymphoid tissue?
lymphocytes
Are there several different classes of lymphocytes depending on their rolls in the immune response?
yes
What two classes of lymphocytes have immune responses that overlap?
-T cell
-B cell
What happens when an unsensitized T-cell and an antigen come into contact?
The unsensitized T-cell will differentiate into a lymphoblast, which then differentiates into lymphokines, killer cells, and memory cells
What is cellular immunity?
T-lymphocytes recognize the antigens and initiate the direct destruction of the antigen by the formation of killer cells and the release of lymphokines
What are cytokines?
chemical mediators released by cellular elements of the immune system, but are not antigen specific
**when these are released by the lymphocytes, they are called lymphokines
What are lymphokines?
chemical mediators released by cellular elements of the immune system, but are not antigen specific
**when these are released by the lymphocytes, they are called lymphokines
What are killer cells?
immune cells that directly attack a cell that contains an antigen
What are memory cells?
cells that reduces the responce time to the second presence of an antigen: the response is quicker
What is humoral immunity?
Immunity that involves the formation of antibodies and B-cells
What is the function of B-cells?
- recognize the antigen and initiate the destruction of the antigen by the formation of antibodies on their cell surface
What happens when a B-cell comes into contact with a macrophage that is presenting an antigen?
the undifferentiated B-cell will differentiate into a lymphoblast, the lymphoblast then differentiates into plasma cells and memory cells
What do macrophages do in the humoral response?
macrophages act as antigen presenting cells
What role do T- helper cells play in humoral immunity?
-T-helper cell aid B-cells in the recognition of the antigen
What role do T- suppressor cells play in humoral immunity?
T-suppressor cells recognize our own cells and do not see them as foreign so we don't destroy ourselves
What is the function of plasma cells?
What makes plasma cells?
-they produce antibodies
-B-cells
What is the function of monocytes?
differentiate into a variety of macrophages for phagocytosis
What are granulocytes?
Do these cells differentiate?
eosinophils, basophils,neutrophils
-these cells contain specific granules
-no
What are the three types of lymphatic tissue based on their cellular content?
-loose lymphatic tissue
-dense lymphatic tissue
-nodular lymphatic tissue
What is loose lymphatic tissue composed of?
predominatly meshwork of reticular cells
What is dense lymphatic tissue composed of?
predominatly lymphocytes(free cells), a few reticular cells
-often cannot see reticular cells due to lymphocytes
What is nodular lymphatic tissue composed of?
What does nodular lymphatic tissue look like?
-free cells predominate
-appear typically as spherical structures/circular structure
What does non-encapsulated lymphatic tissue mean and where can it be found?
-means there is no CT capsule surrounding the tissue
-found in the lamina propria of the GI tract, respiratory system and urinary system
What does MALT stand for?
What does GALT stand for?
What does BALT stand for?
-mucosa associated lymphatic tissue
-gut associated lymphatic tissue
-bronchiole associated lymphatic tissue
In the lamina propria of the GI tract, respiratory system and urinary system, where is the loose connective tissue located?
directly under the epithelium
Why is the loose connective tissue of the lamina propria in the GI tract, respiratory system and urinary system considered part of the lymphatic system?
-because numerous lymphocytes can be found here
- the loose CT is not highly organized and lymphocytes can enter and function here.
What is a solitary lymph nodule?
a dense aggregation of lymphatic tissue forming a spherical mass
What does a solitary lymph nodule contain?
-reticular cells
-reticular fibers
-lymphocytes that are suspended in cells and fibers
Is a solitary lymph nodule a permanent sturcture? Why?
-No
-they increase w/ humoral immune response and decrease after the response is over
Where are solitary lymph nodules located?
in the lamina propria of the GI tract, urinary and respiratory systems
What is the general structure of a solitary lymph nodule?
contains a Cortex(corona) and a Germinal center with no capsule
What is the cortex of a lymphoid structure?
an outer dense staining region that contains small T-lymphocytes, mostly
T-helper cells
What is the germinal center of a lymphoid structure?
a lighter staining region, containing large cells undergoing proliferation and lympnoblast transformation
Are lymphoid structers with a germinal center undergoing a cellular or humoral immune response?
a humoral immune response
What type of cells does a germinal center contain?
-B-lymphocytes
-plasma cells
-reticular cells
What is an aggregate nodule?
an aggregation of solitary lymph nodules- up to the hundreds
What is an example of an aggregate nodule?
Where can this example be found?
-Peyer's patches
-in the lamina propria of the ileum on the side opposite of the attachment of the mesentaries
What is the function of aggragate nodules (peyer's patches)?
production of antibodies during the humoral immune response
What are partially encapsulated lymphatic organs?
lymphatic organs that are not totally surrounded by a capsule
What is an example of the partially encapsulated lymphatic organs?
tonsils
What are some general characteristics of tonsils (partially encapsulated lymphatic organs)?
-the surface that faces the throat wall is covered by epithelium, contains infoldings called crypts that are lined w/ epithelium
-the surface facing into the throat contains CT
-some coarse internal framework called trabeculae is present
What are crypts?
epithelial lined infoldings on tonsils
What three tonsillar groups form a ring about the entrance of the throat- are associated with the nasal pharynx and where are they located?
-palatine tonsils, on either side of the throat
-lingual tonsils, on either side of the uvula on the tongue
-pharyngeal tonsils, a ring of lymphoid tissue encircling the throat
Where are palatine tonsils located?
laterally at the enterance of the throat between the two folds in the pharyngeal wall
What types of lymphatic tissue is in the palatine tonsils?
dense lymphatic tissue and nodular lymphatic tissue arranges around the enfolding of the epithelium
What type of epithelium is on the surface of palatine tonsils?
stratified squamous epithelium
What are some characteristics of crypts in palatine tonsils?
-10-20 finger-like invaginations of the epithelium surrounded by lymphatic tissue
-on the slide, crypts can go down through the surface or they can be seen in cross section,can tell those in cross section by noticing the stratified squamous epithelium
In palatine tonsils, a partial capsule is also known as what?
hemi-capsulation
In palatine tonsils, what is trabeculae?
-CT partitions seen from the CT deep into the tonsil,almost all the way to the surface crypts
-trabeculae contain blood vessels inside of them near the surface
In palatine tonsils, where are mucous galnds located?
What are the function of the mucous glands?
-beneath the tonsil
-they do not empty into the crypts, which is why palatine tonsils get inflamed, they are not washed out
-their functionis protective, they contribute to the saliva in the oral cavity to make it slimy
Where are lingual tonsils located?
on the root of the tongue behind the vallate papillae
How are lingual tonsils arranged?
-are actually clusters of lymphatic tissue separated from each other
-an aggregation of 35-100 individual units
What type of lymphatic tissue is in the lingual tonsil?
dense lymphatic tissue and noduler lymphatic tissue
What are some characteristics of lingual tonsil crypts?
-surface covered by stratified squamous epithelium
-there is generally a single crypt per unit of lymphatic tissue that may branch
Where are the mucous glands of the lingual tonsil located?
Where do they empty into?
-beneath the tonsils, embedded in the skeletal muscle of the tongue
-empty into the base of the crypts
**possible reason lingual tonsils are seldom removed- crypts are cleaned by mucous
Where are pharyngeal tonsils located?
posterior wall of the nasopharynx
What type of lymphatic tissue is in pharyngeal tonsils?
dense lymphatic tissue and nodular lymphatic tissue
What type of epithelium covers the surface of pharyngeal tonsils?
pseudostratified columnar epithelium with cilia
**this is how you distinguish the palatine tonsil
Do pharyngeal tonsils contain crypts?
No- they contain folds but no crypts
What type of gland is associated with the pharyngeal tonsil that is different from the others?
Where are they located?
Where do the gland empty?
-sero-mucous glands
-beneath the tonsil
-empty into the troughs of the folds
What is the function of tonsils?
-lymphopoiesis
-antibody production
What are examples of encapsulated lymphatic organs?
lymph nodes
spleen
thymus
What are five characteristics of lymph nodes?
-shape
-yes,no encapsulated
-structure
-sinuses
-types of lymphatic vessels
1. kidney bean shaped
2. encapsulated
3. contains cortex (outer layer) and medulla (inner layer)
4. lymph sinuses are cleaned w/ lymph
5. contain afferent and efferent lymphatic vessels
What do afferent lymphatic vessels do?
What do efferent lymphatic vessels do?
-bring lymph to a lymph organ
-take away lymph from a lymph organ
What is the parenchyma of the lymph nodes?
functional units of the lymph organ
What is the stroma of the lymph organ?
the CT framework of a lymph organ
What are the components of the stroma of the lymph organ
-Capsule=fibroelastic CT and some smooth muscle, on outside of organ

-trabeculae= CT projections from the capsule which partially subdivide the organ

-reticular CT= CT of stroma
What are lymph sinuses in lymph nodes?
-located under the capsule
-are spaces for the movement of lymph through the node
-are not lined by endothelium
-are looser areas of lymphatic tissue surrounded by many reticular cells that are surrounded by reticular fibers
What is the cortex of a lymph node and what composes it?
-the outer region of the lymph node
-lymph nodules, the paracortical region/deep cortex, the sucapsular sinuses and peritrabecular sinuses
What are some characteristics of the paracortical region/deep cortex?
-located between the lymph nodules and the medulla
-contains an abundance of T-lymphocytes
-contains postcapillary venules
What are post-capillary venules in lymph nodes?
-venules on the venuous side on the capillary bed
-lined by simple cuboidal epithelium (not simple squamous)
-allows T-lymphocytes to enter the lymph node from the peripheral blood
Where are subcapsular sinuses located?
Where are peritrabecular sinuses located?
-under the capsule
-around the CT trabeculae
Where is the medulla of the lymph nodes and what composes it?
-is the center portion of the organ
-contains medullary cords, and medullary sinuses
What are medullary cords?
cords of lymphatic tissue surrounding blood vessels that contain B-lymphocytes, plasma cells, macrophages, and reticular cells
What are medullary sinuses?
-large irregular spaces between the cords
-forms a complex of vessels that exit the hilus as the efferent lymph vessels
-contains reticular cells and lymphocytes
What are the two types of lymphatic vessels?
-afferent vessels
-efferent vessels
What are some characteristics of lymphatic vessels?
-have similar structure to veins
-contain valves
-lumen contains precipitated lymph-light pink
-is embedded in CT of the lymph organ
-sometimes has red blood cells but not often
Where do afferent vessels enter lymph nodes?
Where do efferent vessels exit lymph nodes?
-pass through the capsule,opposite the hilus
-exit the hilus
What is the filtration of lymph pathway?
-afferent vessel
-subcapsular sinus
-peritrabecular sinus
-medullary sinus
-parenchema
-efferent vessel
Where do blood vessels enter lymph nodes?
How do blood vessels get to parenchyma tissue?
-at the hilus
-travel through the trabeculae
*** there is no communication between the lymph sinuses and the blood vessels
What type of nerves are in lymph nodes and where are they located?
-vasomotor only
-the nerves innervate the smooth muscle of the blood vessels
How is lymph filtered in lymph nodes?
by the phagocytosis of particles by macrophages which are found along the lymph sinuses
In the spleen, what compses the stroma?
-capsule
-trabeculae
-reticular CT
In the spleen, what is the capsule composed of?
What is the smooth muscle for?
-fibro-elastic CT w/ some smooth muscle
**fribro=collagen
-smooth muscle can squeeze RBC's out of the spleen
In the spleen, what is the trabeculae composed of?
dense CT containing blood vessels
In the spleen, what cells are suspended in the reticular CT?
lymphocytes
What two components make up the parenchyma of the spleen?
-white pulp
-red pulp
What is white pulp of the spleen?
What is its function?
-lymphatic portion/region of the spleen,dark area with white circles
-filtration of the blood
What are the arteries called in the center of the white pulp in the spleen?
-central arteries, may be more than one
What is a layer of dense lymphatic tissue called surrounding the central artery in the spleen?
periarterial sheath
What are two characteristics of the periarterial sheath in the spleen?
-rich in T-lymphocytes
-may contain germinal centers when infected/inflamed
What is the red pulp in the spleen?
-blood vascular portion of the spleen
**lymph nodes filter lymph, spleen filters blood
What are splenic or billroth's cords?
-cords of lymphatic tissue in the red pulp
-composed of several cells macrophages, B-lymphocytes,reticular cells, and blood cells
What are venous sinusoids?
-spaces in between the billroth's cords in the spleen
-are endothelial lined blood vessels that look like white spaces between Bilroth's cords
-are dialated capillaries after the capillary bed
Is the tissue of the spleen organized around the blood vessels?
yes
What are the arteries of the spleen?
-trabecular arteries
-central artery of the pulp
-penicillar arteries/arteries of the red pulp
Where does the trabecular artery branch from?
-it is a branch of the splenic artery, from the celiac trunk
-is inside the trabeculae of the spleen
Where does the central artery of the pulp in the spleen branch from?
-is a branch from the trabecular artery
-is surrounded by the periarterial sheath
Where does the penicillar arteries in the spleen branch from?
-it branches from the central artery that enters the red pulp after the central artery leaves the periarterial sheath
What are the three extensions of the penicillar artery?
-pulp arterioles
-sheathed arterioles
-terminal capillaries
What is a characteristic of pulp arterioles?
they are surrounded by smooth muscles
What is a characteristic of sheathed arterioles?
they are surrounded by reticular cells
What is a characteristic of terminal capillaries?
they are joined with the venous sinusoids
What are venous sinusoids in the spleen?
-they are a system of endothelial lined tunnels within the red pulp
-they are a true blood vessel, unlike lymph sinusoids
What is the function of venous sinusoids?
-to slow the blood down so it can be filtered in the spleen
-phagocytize old RBC's
-to get nutrients out of the blood in the hepatic sinusoids
What are some characteristics of the venous sinusoids?
-barrel shaped in general
-endothelial cells are rod-shaped
-reticular fibers encircle cells to render support
-basal lamina is fenestrated, ther is a free flow of cells in and out of the sinusoid
-are leaky structures
What types of veins are in the spleen?
-venous sinusoids
-splenic veins
-trabecular veins
-pulp veins
What is the open theory of arterio-venous communication?
The arterial capillaries open into the parenchyma(splenic cords) of the organ, and blood passes between the cells of thesplenic cords to enter the venous sinusoids
What is the closed theory of arterio-venous communication?
Arterial capillaries are continous with the venous sinusoids and thus blood passes directly into the venous sinusoids
Are lymphatic vessels in the spleen efferent, afferent or both?
efferent only
-the only lymph organ that has efferent and afferent vessels is the lymph node
What nerves are in the spleen?
-vasomotor
-innervates smooth muscle
What are the five functions of the spleen?
1. filters the blood
2. hemopoieses- mainly lymphocytes and monocytes
3. phagocytosis of RBC's-old & damaged
4. antibody production- germinal centers
5. blood reservoir
What are the characteristics of the thymus that are only seen until a person hits puberty?
1. bilobed
2. has a cortex and medulla w/ no germinal centers
3. no lymphatic nodules
4. hassall's body or thymic corpuscles
What distinguishes the thymus from a lymph node?
the thymus has no lymphatic nodules
Does the thymus participate in humoral immunity?
no, the thymus produces T-lymphocytes
What are the components of the stroma of the thymus?
-capsule
-septae
-epithelial-reticular cells
***these are different from other organs
What are epithelial-reticular cells in the thymus?
these cells from the supporting system for the lymphatics of the thymus
What makes epithelial-reticular cells different from the reticular cells found in all of the other lymphatic organs?
-they come from endoderm and do not have the ability to produce reticular fibers
What hold the cell processes of the epithelial-reticular cells together?
epithelial-reticular cell processes are held together by desmosomes because there are no reticular fibers to hold them together
What is the parenchyma of the thymus composed of?
-cortex
-medulla
What is the cortex of the thymus composed of?
-dense lymphatic tissue, no lymphatic nodules
-contain thymocytes
What are thymocytes?
is another term for T lymphocyted in the thymus
What composes the medulla of the thymus?
-lots of epithelial-reticular cells, is a lighter staining region
-thymocytes
-hassall's body or thymic corpuscles
What is hassall's body or thymic corpuscles?
-flattened concentric arrays of individual epithelial reticular cells
-these undergo kertinization
-these undergo calcification with age
How is the blood distributed in the thymus?
blood vessels travel in the septae to capillaries in the parenchyma
Are there efferent or afferent lymphatics in the thymus?
efferent only
What types of nerves are in the thymus?
vasomotor nerves only
What are the functions of the thymus?
1. lymphopoiesis
2. maturation of the T-lymphocytes
**80% of the peripheral lymphocytes are T-lymphocytes
In what stage of life is the thymus most important?
-from birth to puberty
-because by then we have built up a population of T-cells in all areas of the body
-at puberty the thymus begins to shrink and T-cells proliferate by mitosis
What is the progression of cells that form the monomuclear phagocytic system?
-precursor cells in bone marrow
-promonocytes
-monocytes in blood
-macrophages in tissue
What is the mononuclear phagocytic system?
-involves all of the macrophages in the body
-all have a common precursor cell found in the bone marrow
What is the macrophage of the mononuclear phagocytic system found in the connective tissue?
histocytes or macrophages
What is the macrophage of the mononuclear phagocytic system found in the liver?
kupffer cells
What is the macrophage of the mononuclear phagocytic system found in the lung?
alveolar macrophage or dust cell
What is the macrophage of the mononuclear phagocytic system found in the spleen and lymph nodes?
free and fixed macrophages
What is the macrophage of the mononuclear phagocytic system found in the bone marrow?
macrophage
What is the macrophage of the mononuclear phagocytic system found in the serous cavity?
pleural and peritoneal macrophages
What is the macrophage of the mononuclear phagocytic system found in the nervous system?
microglia
What is the macrophage of the mononuclear phagocytic system found in the bone?
osteoclast
What is the macrophage of the mononuclear phagocytic system found in the cementum?
cementoclast
What is the macrophage of the mononuclear phagocytic system found in the skin?
langerhans cell