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Flashcards in Body's Defenses Deck (22):
1

Define: immune response

The immune system's response to a threat

2

List and briefly describe 3 important aspects of the adaptive body defense. (3)

1. Antigen- specific → recognizes and acts against particular pathogens or foreign substances
2. Systemic → immunity is not restricted to the initiated infection site
3. “Memory” → it recognizes and mounts even stronger attacks on previously encountered pathogens

3

Define: antigen

Any substance capable of mobilizing out immune system and provoking an immune response

4

What are the 2 crucial cells of the adaptive defense? (2)

1. Lymphocytes
2. Antigen-presenting cells (APCs)

5

Name and briefly describe the 2 major categories of lymphocytes. (2)

1. B lymphocytes (B cells) → produce antibodies and oversee humoral immunity
2. T lymphocytes (T cells) → are non-antibody producing lymphocytes

6

State the 3 stages in the lymphocyte process. (3)

1. Undergo maturing process (2-3 days) directed by the thymic hormones (thymosin)
2. When lymph nodes bind with recognized antigens, they complete their differentiation into fully mature T and B cells
3. Antigen-activated (mature lymphocytes) effector and memory cells circulate continuously in the blood stream and lymphoid organs of the body

7

Where do lymphocytes originate from?

Hemocytoblasts in the red marrow

8

What happens to lymphocytes which bind to self-antigens?

They are vigorously weeded out and destroyed

9

Are immature lymphocytes released from the marrow identical?

Yes

10

How do immature lymphocytes differentiate into B or T cells? (2)

1. T cells arise from the lymphocytes that migrate to the thymus
2. B cells develop immunocompetence in bone marrow

11

How many antigens can a single, immunocompetent lymphocyte react to?

Only the one, distinct antigen

12

Where do T and B cells migrate to after gaining immunocompetence?

Both T and B cells migrate to the lymph nodes and spleen (loose connective tissue) where encounters with antigens occur

13

What is the effect of the chemicals activated T cells release?

Activated T cells release chemicals that prod macrophages into becoming activated macrophages → they secrete bacterial chemicals

14

Where do macrophages and T cells go in the body?

1. Macrophages remain fixed in lymphoid organs
2. T cells circulate

15

What is the major role of antigen-presenting cells in immunity?

1. Engulf antigens
2. Present fragments of antigens like signals flags so that they can be recognized by T cells

16

What do dendritic cells act as?

Mobile sentinels

17

What do macrophages act as in the defensive system?

Phagocytes

18

When are B lymphocytes stimulated to complete their development?

When antigens bind to their surface receptors → lymphocyte becomes primed

19

What do lymphocytes undergo after the binding event?

Clonal selections

20

What do the B cell clones become? (2)

1. Most become plasma cells
2. The rest become memory cells (which can respond at a later time)

21

What are later immune responses called?

Secondary humoral responses

22

What is active immunity?

When B cells encounter antigens and produce antibodies