Lymphoid Organs: Thymus, Spleen, and Tonsils Flashcards Preview

Molecules and Cells (Unit 1) > Lymphoid Organs: Thymus, Spleen, and Tonsils > Flashcards

Flashcards in Lymphoid Organs: Thymus, Spleen, and Tonsils Deck (80)
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1
Q

The appendix is a significant part of the mucousa associated ymphoid tissue with its ________ and __________ filled with lymphocytes and lymphoid follicles.

A

Lamina propria; submucosa

2
Q

What is the role of the epithelial reticular cells of the thymus?

A

Form the structural component of the parenchyma, which lacks collagen

3
Q

What are the major components of the parenchyma of the spleen?

A

White Pulp

Red Pulp

4
Q

What is the role of thymic nurse cells?

A

They can engulf as many as 20 lymphocytes. A portion of those lymphocytes are released, which the other portion undergo apoptosis

5
Q

HEVs are found in the _____________ of lymph nodes

A

paracortex

6
Q

The palatine tonsil is invaginated by deep grooves called ___________

A

Tonsillar Crypts

7
Q

Is the thymus encapsulated or not capsulated? What can be found between the two lobes of the thymus? What can those lobes further be compartmentalized into?

A

Encapsulated; Septa; Cortex and Medulla

8
Q

What are the two main tissue architecture types of lymphoid sytem?

A

Diffuse

Follucular

9
Q

Lymphocytes originate in __________

A

Bone Marrow

10
Q

Foreign proteins that have been phagocytized are transferred to vesicles containing ________ protein of antigen-presenting cells. This attracts the attention of ____________ cells that stimulate the production of _______ against the bacterium.

A

MHC II; Helper T; antibodies

11
Q

Central arteries are surrounded by _____________ of T- cells.

A

Peri-Arteriolar Lymphoid Sheath

12
Q

Two types of specific resistance

A

Cell-mediated immunity

Antibody- mediated immunity

13
Q

What are the roles of the secondary lymphatic organs? What are the secondary lymphatic organs/tissues?

A

Site where most immune responses occur

Lymph nodes, spleen, and lymphatic nodules

14
Q

Which of the Major Histocompatibility Complexes is found in all nucleated cells?

A

MHC I

15
Q

Thymus undergoes _____ with less activity in the adult. Atrophy of the ____, which is partially replaced by _________

A

Involution; parenchyma; adipose tissue

16
Q

The pharyngeal tonsil covered by ____________ epithelium

A

pseudostratified columnar

17
Q

What is the difference between epithelium in palatine tonsil vs epithelium in lingual tonsil?

A

The lingual tonsil epithelium is surrounded by skeletal muscle

18
Q

A specialized subtype of reticular epithelial cells

A

Thymic nurse cells

19
Q

How can the cortex be distinguished from the medulla of the thymus?

A

The cortex is darkly stained with densely packed lymphocytes. The medulla is lighter stained with fewer lymphocytes but more epithelial reticular cells.

20
Q

Antigen- presenting cells display antigens alongside _________

A

Major Histocompatibility Proteins (MHC)

21
Q

Helper T cells stimulate ______ cells

A

B

22
Q

What are the major roles of the lymphatic system?

A

Draining excess intersitial fluid and plasma proteins from the tissue spance

Transporting dietary lipids and vitamins from GI tract to the blood

Facilitating immune response

23
Q

Steps to stimulation of Cytotoxic T Cells

A
  1. CD8 binds to the MHC I molecule of various cells. Cell receptor on the cytotoxic cell binds with the abnormal antigen of the various cells.
  2. Interleukin 2 that is released from the Helper T Cell activated the cytotoxic T cell
  3. Activated cytotoxic T cell proliferates and differentiates into activated and memory cytotoxic t cells
24
Q

_________ of cortical capillaries prevent entry of blood-borne molecules into the cortex of the thymus. This prevents exposure of developing_________ to _________, which could cause their apoptosis.

A

Tight junctions; T cells; Plasma antigens

25
Q

What type of cells make up the stroma? Is the stroma visible and clear?

A

Epithelial cells; No they are oscured by the lymphocytes

26
Q

What tissue makes up the capsule of Palatine Tonsils?

A

Dense irregular connective tissue

27
Q

What are the components of the Splenic sinuses?

A

Full of blood because the spleen acts as a filter of blood. They are lined by endothelium

28
Q

Where are the B cells located in the Spleen?

A

In the germinal center of follicles found in the white pulp

29
Q

What are the functions of epithelial reticular cells?

A

Attract lymphocytes to the thymus and guide their development

30
Q

What is the stroma?

A

Supporting cellular framework of connective tissue which contains blood vessels and nerves and gives structure to the thymus

31
Q

Cytotoxic T cells have which protein?

A

CD8

32
Q

What are the components of the Cords of Billroth?

A

WBCs, macrophages, RBCs, B and T lymphocytes

33
Q

What are the cells of the thymus?

A

Pre T cells

T lymphocytes

Epithelial reticular cells

Thymic nurse cells

Dendritic cells

34
Q

Where do thymic dendritic cells originate? What is their function?

A

They originate in bone marrow.

They stimulate development of regulatory T cells that suppress reactions to self-proteins

35
Q

What can be found beneath the epithelium of palatine tonsils?

A

Lymphatic nodules in connective tissue

36
Q

_________surrounds the white pulp and is divided to __________ and ___________.

A

Red Pulp; splenic cords; spenic sinuses

37
Q

The lingual tonsil is covered by ____________epithelium

A

Stratified squamous

38
Q

Which organs are apart of the lymphatic system?

A

Red Bone marror

Thymus

Spleen

Lymph nodes

Tonsils

39
Q

What is nonspecific resistance to disease?

A

General defensive mechanisms effective on a wide range of pathogens

40
Q

The thymus is a _____ lymphoid orgain in that it supplies other lymphoid organs and tissues with __________

A

Primary; T- Lymphocytes

41
Q

Examples of a Mucousa associated lymphoid tissue

A

Appendix

42
Q

How are millions of different types of lymphocytes generated?

A

In the parenchyma, T-cell receptor genes are rearranged so that mature T cells obtain specific surface markers

43
Q

All T lymphocytes have cell surface protein receptors (TCRs) with variable regions that recognize specific antigens. Cell activation requires costimulation by the ____________ and either ________ or _________, which characterize helper and cytotoxic T cells, respectively

A

TCR; CD4; CD8

44
Q

How do RBCs leave the spleen?

A

They must push past macrophages to enter sinusoids and leave the spleen

45
Q

__________ play an important role in isolating T cells from __________ during their development.

A

Stroma; foreign antigens

46
Q

Why do lymphocytes adhere to HEVs?

A

HEVs possess addressin proteins that bind to selectin proteins of lymphocytes.

47
Q

What makes up the capsule of lympoid tissue?

A

Connective tissue

48
Q

Is the spleen and encapsulated organ?

A

Yes

49
Q

Steps to stimulation of Helper T Cells

A
  1. CD4 binds to MHCII molecule of the antigen presenting cell. The helper T cell receptor interacts with antigen on the antigen presenting cell
  2. Helper T Cells secrete Interleukin 2 which stimulates the helper T lymphocytes
  3. Activated T Lymphocytes proliferate and differentiate to produce new activated and memory T Lymphocytes
50
Q

In the medulla, epithelial reticular cells also form ___________

A

Hassall’s Corpuscles

51
Q

The capsule of the spleen extends to form ________ which contain the ___________ and _________-

A

Trabeculae; trabecular arteries; trabecular veins

52
Q

Are the tonsils capsulated?

A

Partly

53
Q

Components of Red Pulp

A

Cord of Billroth

Sinuses

Stroma

54
Q

What is the mechanism for lymphocyte migration to the tonsils?

A

The specialized cubodial endothelium cells of HEVs possess proteins that slow down lymphocytes and encourage them to exit the HEV and enter the tonsil

55
Q

What are the two distinct areas of lymphoid follicles? How can they be distinguished?

A

Mantle- darker stained, smaller, resting lymphocytes

Germinal center- Lighter stained, larger, activated B cells

56
Q

What is the role of epithelial reticular cells in the Hassall’s corpuscles? What affect does this have?

A

Epithelial reticular cells of the Hassall’s corpuscles secrete Thymic Stromal Lymphopoietin( TSL).

TSL stimulate dendritic cells to hasten the maturation of regulatory T cells that suppress the auto-immune reactions against “self” proteins.

57
Q

What is the MHC pathway for endogenous antigens digested in proteosomes?

A
  1. MHC I and antigen formed in rER
  2. Travel to Golgi
  3. Travel to vesicle
  4. Mets with the Cytotoxic T- Cell (CD8)
58
Q

_____% of T cells formed in the thymus are destroyed to prevent reactions againts “self” proteins.

A

95

59
Q

What happens in the “nude miuse” case?

A

The mouse has defects in karatin- containing hair follicles and in keratin-containg thymic epithelial reticular cells. The mice cannot grow hair, and can not populate a thymus with lymphocytes, and so cannot reject the skin grafts from other mice.

60
Q

Pre T cells enter the _______ and are “educated” by ________ cells. The T cells are then released from the cortex for final stimulation by __________ in the medulla.

A

Cortex; Reticular epithelial; dedritic cells

61
Q

Macrophages present antigens to ___________-

A

Lymphocytes

62
Q

What are the three types of T Cells

A

Cytotoxic

Helper

Regulatory T Cells

63
Q

What is the vascular pattern of the spleen?

A
  1. Trabecular artery
  2. Central arteriole
  3. Penicillar arterioles
  4. Sheathed capillaries
  5. Trabecular vein
64
Q

What are the two types of lymphoid tissue? Which organs fall under each type?

A

Encapsulated (Spleen, Thymus, Lymph Nodes)

Unencapsulated (Tonsils, Peyer’s Patches, Lymphoid nodules in GI tract, respiratory tract, urinary and reproductive tracts)

65
Q

Which lymph organ lacks lymph follicles?

A

Thymus because it has no B cells

66
Q

Do all lymphoid follicles have geminal centers?

A

No

67
Q

The surface of the palatine tonsil is covered by ___________ epithelium.

A

Stratified squamous nonkeratinized epithelium

68
Q

Where are dendritic cells located?

A

Medulla

69
Q

A subtype of epithelial reticular cells expresses a huge variety of proteins under the command of a transcription facter called ___________. How many proteins are expressed? What happens if a T cell binds to these proteins?

A

AIRE (Autoimmune Regulatory protein)

3000

It is killed via apoptosis

70
Q

What is the parenchyma?

A

The epithelial, secreting cells of the thymus which perform the thymus’s essential function

71
Q

_________________ is a cytokine that induces differentiation of naive helper T cells (Th0 cells) to Th2 cells.

A

The interleukin 4 (IL4, IL-4)

72
Q

_________ cells migrate to the thymus for further development.

A

Pre-T

73
Q

What are the two tissue components of the thymus?

A

The parenchyma and stroma

74
Q

What is lymphoid tissue?

A

Connective tissue with a rich supply of lymphocytes

75
Q

What are the roles of the primary lymphatic organs? What are the primary lymphatic organs

A

Provide environment for stem cells to divide and mature into B and T lymphocytes

Red bone marrow- Gives rise to mature B cells

Thymus- Give rise to T cells

76
Q

How do cytotoxic T cells kill cells?

A

Secrete protein subunits called perforins, which can form holes in cell membranes

Secrete destructive enzymes called granzymes

Produce pro-apoptotic protein, FAS ligand

77
Q

Mutations in an epithelial transcription factor called __ damages both epithelial cells and the thymus of the “nude mouse”

A

Foxn

78
Q

Helper T Cell have which type of protein?

A

CD4

79
Q

How does the lymphatic system facilitate immune responses?

A

Recognize microbes or abnormal cells and responding by killing them directly or secreting antibodies that cause their destruction

80
Q

Stimulation B lymphocytes (Pathway)

A
  1. Free antigen binds to the B cell receptor. The B cell engulfes, processes, and presents antigen to the Helper T Cells
  2. Interleukin 2 is released from Helper T Cells and stimulate B cells
  3. Activated B Cells proliferate and differentiate into activated and memory cells