export_alterations in body defenses part 1 Flashcards
Classically, immunity takes what two forms?
cellular response and humoral response
___________ immunity employs lymphocytes that directly attack and destroy foreign cells or diseased host cells.
Cellular (cell-mediated)
_______ immunity employs antibodies, which do not directly destroy a pathogen, but tag them for destruction.
Humoral
What are the two main kinds of lymphocytes, and from where are they derived?
a) T-lymphocytes (T-cells) are “born” in the red bone marrow and mature in the thymus.
b) B-lymphocytes (B-cells) are derived from red bone marrow and mature in the bone marrow.
Note: Both T- and B- cells then disperse and colonize lymph nodes, spleen, mucous membranes, intestines, etc. They are also present in the blood.
B-cells produce surface receptors for antigens, called _______ or _______.
immunoglobulins; antibodies
When B-cell surface antibodies come into contact with antigens, the B-cell ___________.
differentiates into a plasma cell.
3 basic mechanisms which account for most T-cell functions:
a) some T-cells are directly cytotoxic
b) some T-cells participate in the release of cytotoxic mediators
c) some T-cells are involved in stimulation of B-lymphocytes
4 stages of differentiation (maturation) of T-cells
1) early cortical
2) late cortical
3) medullary
4) peripheral
in what stage of maturation are most thymic T-cells (thymocytes)?
Late cortical (80%)
Medullary T-cells are half CD4 and half CD8. What does CD stand for and what are other names for these cells?
Cluster designation; CD4 = helper; CD8 = cytotoxic.
of peripheral t-cells (those released into the blood), CD4 make up _____% and CD8 make up _______%.
CD4: 65%
CD8: 35%
Natural killer (NK) cells make up ____% of blood lymphocytes
10-15%
NK cells are the first line of defense against what?
neoplastic (tumor) and virus-infected cells
