Ch2 Tissues

Question 1

What are primary vs secondary lymphoid organs?

Answer 1

Primary: where lymphocytes first express antigen receptors and attain phenotypic and functional maturity (Bone marrow, thymus)
Secondary: where lymphocyte responses to foreign antigens are initiated and develop (lymph nodes, spleen)

Question 2

Why is asymmetric division necessary in an HSC?

Answer 2

Hematopoetic stem cells need to be self renewing, but also give rise to all differentiated cells. So, at least one daughter cell maintains the properties of a stem cell while the other can differentiate along a particular lineage.

Question 3

Name 2 markers for HSC.

Answer 3

CD34 and c-Kit. LIN-neg otherwise.

Question 4

What cells are found in the cortex of the thymus? In the medulla?

Answer 4

Cortex: contains a dense collection of T lymphocytes, cortical epithelial cells which produce IL-7,
Medulla: more sparsely populated with lymphocytes, BMDM and DCs almost exclusively found here, as well as medullary thymic epithelial cells which present self-antigen to T cells.
T cells mature as they go from the cortex to the medulla.

Question 5

What is interstitial fluid?

Answer 5

Plasma draining out of capillaries, lymphatic capillaries that absorb this fluid from spaces between tissue cells