Lecture 37-38: Lymphatic Microanatomy Flashcards
lymphatic capillaries form collecting ______ that contain valves and combine to form trunks or ducts
vessels
where are the tracheal trunks located
along the R and L ventromedial surface of the trachea
what vessels are found in the lumbar trunks
vessels of the medial iliac, caudal mesenteric and lumbar lymph nodes
what vessels are found in the interstinal trunk
vessels of the crainal mesenteric lymph nodes
what vessels are found in the celiac trunk
vessels associated to celiac trunk
what is the cisterna chyli
a sac like dilation of a large lymph node b/w the right side of aorta and right crus of diaphragm
what is the thoracic duct
an extension of the cisterna chyli into the thoracic cavity that runs b/w the azygous vein and the aorta
what vessels are in the right lymphatic duct
vessels of the cranial mediastinal and cranial sternal lymph nodes that empty into the cranial vena cava
what are dendritic cells
those located in lymph nodes
macrophages and B-lymphocytes
main cells involved in the adaptive immune response
lymphocytes (T and B)
what are the two types of Lymphocyte T cells
T cytotoxic (Tc) and T helper (Th)
- involved in cell mediated immune response and activated by antigens
what type of antigens are T cytotoxic and T helper cells activated by
Tc = MHC I in APCs
Th = MHC II in pAPCs
where are lymphocytes made, where are they educated
made in bone marrow, educated in thymus
what type of immune response are lymphocyte B cells involved in
humoral (antibodies) immune response
what are the only nonmyeloid cells that can function as APCs to activate lymphocyte T cells
lymphocyte B cells
what are lymphocyte B cells activated by
antigens and pAPCs (dendritic cells)
Natural killer cells are lymphocytes that work similar to the …..
cells of the innate immune response
target same cells as lymphocyte Tc
antigen breakdown into MHC by APC cells causes the activation of …
lymphocytes Tc
pAPCs break down antigen into MHC II, resulting in the activation of …
lymphocytes Th
pAPCs (dendritic cells) activate _____
lymphocyte B
what is the function of lymphocytes Tc
destroy infected cells and pathogens by secreting proteins (perforins and fragmentins) that induce fragmentation of DNA —> apoptosis
what is the function of lymphocyte Th cells
secrete cytokines that help the activation of lymphocytes B and Tc
what are the 2 types of lymphocytes B
plasma cells - make and secrete antibodies
memory B cells - plasma cells that remain in body and respond more quickly during next antigen encounter
types of lymphoid organs
primary organs = where immune cells develop (bone marrow, thymus)
secondary organs = where immune cells work (lymph nodes, spleen, lymphoid tissue)
what is the stroma of bone marrow made of
reticular cells, reticular fibers (type II collagen) and adipocytes
what is the parenchyma of bone marrow made of
hematopoietic stem cells and differentiating hematopoietic cells
what is the function of bone marrow
hematopoiesis
produces generic form of lymph T cells
produced lymphocytes B
what are the blood sinusoids of the bone marrow
sites of cellular and molecular exchange b/w circulation and hematopoietic compartment
education and differentiation of lymphocytes T occurs where
thymus
composition of the stroma of the thymus
CT (collagen fibers and fibroblasts)
trabeculae (divides parenchyma into lobes)
contains blood vessels, efferent lymphatic vessels and nerves
composition of thymus parenchyma
cortex
corticomedullary junction
medulla
what is the thymus cortex made of
developing lymphocytes T that reside in the meshwork of epithelioreticular cells
what are epithelioreticular cells
specialized cells that contribute to the framework of cortex
create microenvironment for lymphocyte T ‘education’
also present are macrophages that phagocytize lymphocytes that don’t learn
what is the blood thymus barrier
formed by a wall of blood vessels
prevents lymphocyte T cells from coming into contact with antigens
education needs ‘clean env’
what is the corticomedullary junction
made of ERCs, forms barrier b/w cortex and medulla
contains blood vessels, arterioles and venules (high endothelial venules)
specialized post capillary venule for diapedesis and recirculation
site for entrance and exit of lymphocytes
found in most lymphoid organs except the spleen
High endothelial venule
what is the medulla of the thymus made of
loosely packed mature lymphocyte T cells w/ meshwork of epithelioreticular cells
what are Thymic (Hassall’s) corpuscles in the medulla
ERCs concentrically arranged with flat nuclei
lymphocytes are selected in the cortex based on their affinity to bind _____
MHC
what is positive selection and where in the thymus does it occur
lymphocytes that bind MHC receive the survive signal while the others are induced to die
occurs in cortex
lymphocytes are selected in the medulla based on their affinity to bind _____
MHC conjugated to specific antigens (self)
what is negative selection and where does it occur
lymphocytes that bind MHC conjugated to tissue specific antigens are induced to die
occurs in medulla
lymphocytes that get differentiated into Tc and Th leave the medulla through ?
HEVs
encapsulated lymphatic organs that are along lymphatic vessels
lymph nodes
what is the capsule of a lymph node made of
dense CT
what is the trabeculae of lymph node made of
dense CT that forms framework
what is the reticular tissue of lymph nodes made of
reticular cells and fibers that form a fine supporting meshwork
what is the path of lymph flow and blood in the lymph nodes
afferent lymphatic vessel –> subcapsular sinus –> trabecular sinus –> medullary sinus –> efferent lymphatic vessel
white pulp of the spleen
lymphoid nodules are randomly scattered, secondary lymphoid region
red pulp of the spleen
embeds white pulp and contains splenic sinuses
function of myoblasts in the capsule and trabeculae of spleen
discharge RBCs into blood
what are splenic cords within the red pulp
meshwork of reticular cells and fibers
- erythrocytes, macrophages, dendritic cells, plasma cells and megacariocytes reside in the mesh
- macrophages phagocytize damaged RBCs
-megakaryocytes form platelets
what are splenic sinuses within red pulp
spaces lined by endothelial cells
processes of macrophages extend between the cells to monitor antigens
Diffuse lymphoid tissue includes…
mucosa associated lymphatic tissue (MALT)
gut-associated lymphatic tissue (GALT)
bronchus associated lymphatic tissue (BALT)
characteristics of diffuse lymphoid tissue
no cortex or medulla
not surrounded by CT capsule
made of randomly packed lymphocytes
