Lecture 37-38: Lymphatic Microanatomy Flashcards

1
Q

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

A

vessels

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2
Q

where are the tracheal trunks located

A

along the R and L ventromedial surface of the trachea

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3
Q

what vessels are found in the lumbar trunks

A

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

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4
Q

what vessels are found in the interstinal trunk

A

vessels of the crainal mesenteric lymph nodes

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5
Q

what vessels are found in the celiac trunk

A

vessels associated to celiac trunk

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6
Q

what is the cisterna chyli

A

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

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7
Q

what is the thoracic duct

A

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

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8
Q

what vessels are in the right lymphatic duct

A

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

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9
Q

what are dendritic cells

A

those located in lymph nodes

macrophages and B-lymphocytes

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10
Q

main cells involved in the adaptive immune response

A

lymphocytes (T and B)

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11
Q

what are the two types of Lymphocyte T cells

A

T cytotoxic (Tc) and T helper (Th)

  • involved in cell mediated immune response and activated by antigens
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12
Q

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

A

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

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13
Q

where are lymphocytes made, where are they educated

A

made in bone marrow, educated in thymus

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14
Q

what type of immune response are lymphocyte B cells involved in

A

humoral (antibodies) immune response

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15
Q

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

A

lymphocyte B cells

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16
Q

what are lymphocyte B cells activated by

A

antigens and pAPCs (dendritic cells)

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17
Q

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

A

cells of the innate immune response

target same cells as lymphocyte Tc

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18
Q

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

A

lymphocytes Tc

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19
Q

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

A

lymphocytes Th

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20
Q

pAPCs (dendritic cells) activate _____

A

lymphocyte B

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21
Q

what is the function of lymphocytes Tc

A

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

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22
Q

what is the function of lymphocyte Th cells

A

secrete cytokines that help the activation of lymphocytes B and Tc

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23
Q

what are the 2 types of lymphocytes B

A

plasma cells - make and secrete antibodies

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

24
Q

types of lymphoid organs

A

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

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

25
Q

what is the stroma of bone marrow made of

A

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

26
Q

what is the parenchyma of bone marrow made of

A

hematopoietic stem cells and differentiating hematopoietic cells

27
Q

what is the function of bone marrow

A

hematopoiesis
produces generic form of lymph T cells
produced lymphocytes B

28
Q

what are the blood sinusoids of the bone marrow

A

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

29
Q

education and differentiation of lymphocytes T occurs where

A

thymus

30
Q

composition of the stroma of the thymus

A

CT (collagen fibers and fibroblasts)

trabeculae (divides parenchyma into lobes)

contains blood vessels, efferent lymphatic vessels and nerves

31
Q

composition of thymus parenchyma

A

cortex
corticomedullary junction
medulla

32
Q

what is the thymus cortex made of

A

developing lymphocytes T that reside in the meshwork of epithelioreticular cells

33
Q

what are epithelioreticular cells

A

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

34
Q

what is the blood thymus barrier

A

formed by a wall of blood vessels

prevents lymphocyte T cells from coming into contact with antigens

education needs ‘clean env’

35
Q

what is the corticomedullary junction

A

made of ERCs, forms barrier b/w cortex and medulla

contains blood vessels, arterioles and venules (high endothelial venules)

36
Q

specialized post capillary venule for diapedesis and recirculation

site for entrance and exit of lymphocytes

found in most lymphoid organs except the spleen

A

High endothelial venule

37
Q

what is the medulla of the thymus made of

A

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

38
Q

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

A

ERCs concentrically arranged with flat nuclei

39
Q

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

A

MHC

40
Q

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

A

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

occurs in cortex

41
Q

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

A

MHC conjugated to specific antigens (self)

42
Q

what is negative selection and where does it occur

A

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

occurs in medulla

43
Q

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

A

HEVs

44
Q

encapsulated lymphatic organs that are along lymphatic vessels

A

lymph nodes

45
Q

what is the capsule of a lymph node made of

A

dense CT

46
Q

what is the trabeculae of lymph node made of

A

dense CT that forms framework

47
Q

what is the reticular tissue of lymph nodes made of

A

reticular cells and fibers that form a fine supporting meshwork

48
Q

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

A

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

49
Q

white pulp of the spleen

A

lymphoid nodules are randomly scattered, secondary lymphoid region

50
Q

red pulp of the spleen

A

embeds white pulp and contains splenic sinuses

51
Q

function of myoblasts in the capsule and trabeculae of spleen

A

discharge RBCs into blood

52
Q

what are splenic cords within the red pulp

A

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

53
Q

what are splenic sinuses within red pulp

A

spaces lined by endothelial cells

processes of macrophages extend between the cells to monitor antigens

54
Q

Diffuse lymphoid tissue includes…

A

mucosa associated lymphatic tissue (MALT)

gut-associated lymphatic tissue (GALT)

bronchus associated lymphatic tissue (BALT)

55
Q

characteristics of diffuse lymphoid tissue

A

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

56
Q
A