Chapter Three - Thymus & Spleen Flashcards Preview

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Flashcards in Chapter Three - Thymus & Spleen Deck (70)
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0

Is the thymus a primary or secondary lymphoid organ?

Primary

1

At what age do we see that little functioning of the thymus is left?

About 25 years of age

2

Is the thymus larger in a child or an adult?

Child

3

When does involution of the thymus begin?

After puberty

4

What is the pattern of the involution process of the thymus?

1st - septa
2nd - cortex
3rd - medulla

5

What is the important function of the thymus?

Establish immunocompetent T cells

6

What two steps are involved in the thymus establishing immunocompetent T cells?

Being able to distinguish self from non self antigens and to develop self-tolerance

7

What is a thymocyte?

T lymphoblast in the thymus

8

What makes up the thin capsule of the thymus?

Dense irregular connective tissue

9

What makes up the lobules of the thymus?

Peripheral cortex and a central medulla

10

What is the term for the support tissue of the thymus?

Stroma

11

What makes up the stroma of the thymus?

Capsule, septa, adipose, microstroma

12

What is the microstroma of the thymus?

Thymic epithelial cells (TECs)

13

What is another name for thymic epithelial cells?

Epithelioreticular cells or epithelial reticular cells

14

How many types of TECs are there?

6

15

What are the functions of the thymic epithelial cells?

Support using cytoplasmic processes (NOT reticular fibers), secrete thymic hormones and cytokines, form thymic corpuscles (Hassall's bodies), important component to the blood-thymic barrier, function as an APC

16

What are the functions of the hormones and cytokines that can be secreted by TECs?

Influence T cell maturation, division, and activities (immunity elsewhere in the body too)

17

What type of TEC are the thymic corpuscles (Hassell's bodies)?

Type VI

18

Where can thymic corpuscles be found?

In the medulla

19

What is the function of the thymic corpuscles?

Secrete cytokines to influence local dendritic cells and the development of some T cells

20

What type of TEC is found in the blood-thymic barrier?

TEC type I

21

What makes up the perivascular component of the blood-thymic barrier?

Connective tissue with many macrophage to destroy foreign molecules

22

What is the function of the blood-thymic barrier?

To prevent T cells from physically contacting foreign antigens

23

What part of the thymus contains a high cell concentration?

Cortex

24

What cells make up the cortex of the thymus?

T lymphocytes, macrophages, TEC types I, II, and III

25

What part of the thymus contains a lower cell density?

Medulla

26

Where are T lymphoblasts produced?

Bone marrow

27

What cell types are found in the medulla of the thymus?

Fewer but large T cells, macrophages, dendritic cells (APC), and TEC types IV, V, and VI

28

When the T lymphocytes first enter the thymus, are they immunocompetent?

No; they are immunoINcompetent

29

Where do the T lymphocytes leave the bloodstream?

At the corticomedullary line