Lecture 37-38: Lymphatic Microanatomy

Question 1

lymphatic capillaries form collecting ______ that contain valves and combine to form trunks or ducts

Answer 1

vessels

Question 2

where are the tracheal trunks located

Answer 2

along the R and L ventromedial surface of the trachea

Question 3

what vessels are found in the lumbar trunks

Answer 3

vessels of the medial iliac, caudal mesenteric and lumbar lymph nodes

Question 4

what vessels are found in the interstinal trunk

Answer 4

vessels of the crainal mesenteric lymph nodes

Question 5

what vessels are found in the celiac trunk

Answer 5

vessels associated to celiac trunk

Question 6

what is the cisterna chyli

Answer 6

a sac like dilation of a large lymph node b/w the right side of aorta and right crus of diaphragm

Question 7

what is the thoracic duct

Answer 7

an extension of the cisterna chyli into the thoracic cavity that runs b/w the azygous vein and the aorta

Question 8

what vessels are in the right lymphatic duct

Answer 8

vessels of the cranial mediastinal and cranial sternal lymph nodes that empty into the cranial vena cava

Question 9

what are dendritic cells

Answer 9

those located in lymph nodes

macrophages and B-lymphocytes

Question 10

main cells involved in the adaptive immune response

Answer 10

lymphocytes (T and B)

Question 11

what are the two types of Lymphocyte T cells

Answer 11

T cytotoxic (Tc) and T helper (Th)

• involved in cell mediated immune response and activated by antigens

Question 12

what type of antigens are T cytotoxic and T helper cells activated by

Answer 12

Tc = MHC I in APCs
Th = MHC II in pAPCs

Question 13

where are lymphocytes made, where are they educated

Answer 13

made in bone marrow, educated in thymus

Question 14

what type of immune response are lymphocyte B cells involved in

Answer 14

humoral (antibodies) immune response

Question 15

what are the only nonmyeloid cells that can function as APCs to activate lymphocyte T cells

Answer 15

lymphocyte B cells

Question 16

what are lymphocyte B cells activated by

Answer 16

antigens and pAPCs (dendritic cells)

Question 17

Natural killer cells are lymphocytes that work similar to the …..

Answer 17

cells of the innate immune response

target same cells as lymphocyte Tc

Question 18

antigen breakdown into MHC by APC cells causes the activation of …

Answer 18

lymphocytes Tc

Question 19

pAPCs break down antigen into MHC II, resulting in the activation of …

Answer 19

lymphocytes Th

Question 20

pAPCs (dendritic cells) activate _____

Answer 20

lymphocyte B

Question 21

what is the function of lymphocytes Tc

Answer 21

destroy infected cells and pathogens by secreting proteins (perforins and fragmentins) that induce fragmentation of DNA —> apoptosis

Question 22

what is the function of lymphocyte Th cells

Answer 22

secrete cytokines that help the activation of lymphocytes B and Tc

Question 23

what are the 2 types of lymphocytes B

Answer 23

plasma cells - make and secrete antibodies

memory B cells - plasma cells that remain in body and respond more quickly during next antigen encounter

Question 24

types of lymphoid organs

Answer 24

primary organs = where immune cells develop (bone marrow, thymus)

secondary organs = where immune cells work (lymph nodes, spleen, lymphoid tissue)

Question 25

what is the stroma of bone marrow made of

Answer 25

reticular cells, reticular fibers (type II collagen) and adipocytes

Question 26

what is the parenchyma of bone marrow made of

Answer 26

hematopoietic stem cells and differentiating hematopoietic cells

Question 27

what is the function of bone marrow

Answer 27

hematopoiesis produces generic form of lymph T cells produced lymphocytes B

Question 28

what are the blood sinusoids of the bone marrow

Answer 28

sites of cellular and molecular exchange b/w circulation and hematopoietic compartment

Question 29

education and differentiation of lymphocytes T occurs where

Answer 29

thymus

Question 30

composition of the stroma of the thymus

Answer 30

CT (collagen fibers and fibroblasts) trabeculae (divides parenchyma into lobes) contains blood vessels, efferent lymphatic vessels and nerves

Question 31

composition of thymus parenchyma

Answer 31

cortex corticomedullary junction medulla

Question 32

what is the thymus cortex made of

Answer 32

developing lymphocytes T that reside in the meshwork of epithelioreticular cells

Question 33

what are epithelioreticular cells

Answer 33

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

Question 34

what is the blood thymus barrier

Answer 34

formed by a wall of blood vessels prevents lymphocyte T cells from coming into contact with antigens education needs 'clean env'

Question 35

what is the corticomedullary junction

Answer 35

made of ERCs, forms barrier b/w cortex and medulla contains blood vessels, arterioles and venules (high endothelial venules)

Question 36

specialized post capillary venule for diapedesis and recirculation site for entrance and exit of lymphocytes found in most lymphoid organs except the spleen

Answer 36

High endothelial venule

Question 37

what is the medulla of the thymus made of

Answer 37

loosely packed mature lymphocyte T cells w/ meshwork of epithelioreticular cells

Question 38

what are Thymic (Hassall's) corpuscles in the medulla

Answer 38

ERCs concentrically arranged with flat nuclei

Question 39

lymphocytes are selected in the cortex based on their affinity to bind _____

Answer 39

MHC

Question 40

what is positive selection and where in the thymus does it occur

Answer 40

lymphocytes that bind MHC receive the survive signal while the others are induced to die occurs in cortex

Question 41

lymphocytes are selected in the medulla based on their affinity to bind _____

Answer 41

MHC conjugated to specific antigens (self)

Question 42

what is negative selection and where does it occur

Answer 42

lymphocytes that bind MHC conjugated to tissue specific antigens are induced to die occurs in medulla

Question 43

lymphocytes that get differentiated into Tc and Th leave the medulla through ?

Answer 43

HEVs

Question 44

encapsulated lymphatic organs that are along lymphatic vessels

Answer 44

lymph nodes

Question 45

what is the capsule of a lymph node made of

Answer 45

dense CT

Question 46

what is the trabeculae of lymph node made of

Answer 46

dense CT that forms framework

Question 47

what is the reticular tissue of lymph nodes made of

Answer 47

reticular cells and fibers that form a fine supporting meshwork

Question 48

what is the path of lymph flow and blood in the lymph nodes

Answer 48

afferent lymphatic vessel --> subcapsular sinus --> trabecular sinus --> medullary sinus --> efferent lymphatic vessel

Question 49

white pulp of the spleen

Answer 49

lymphoid nodules are randomly scattered, secondary lymphoid region

Question 50

red pulp of the spleen

Answer 50

embeds white pulp and contains splenic sinuses

Question 51

function of myoblasts in the capsule and trabeculae of spleen

Answer 51

discharge RBCs into blood

Question 52

what are splenic cords within the red pulp

Answer 52

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

Question 53

what are splenic sinuses within red pulp

Answer 53

spaces lined by endothelial cells processes of macrophages extend between the cells to monitor antigens

Question 54

Diffuse lymphoid tissue includes...

Answer 54

mucosa associated lymphatic tissue (MALT) gut-associated lymphatic tissue (GALT) bronchus associated lymphatic tissue (BALT)

Question 55

characteristics of diffuse lymphoid tissue

Answer 55

no cortex or medulla not surrounded by CT capsule made of randomly packed lymphocytes