ch. 20

Question 1

Innate (nonspecific) system:

Answer 1

first line of defense: intact skin and mucous membranes; Additional defenses includes phagocytes (second line of defense);

Question 2

Adaptive (specific) defense system (third line of defense):

Answer 2

works with the previous defenses, is an attack against particular foreign antigens by activated lymphocytes.

Question 3

Innate (nonspecific) defenses:

Answer 3

Phagocytes: macrophages (develop from monocytes), neutrophils; process of phagocytosis.

Question 4

Adaptive (specific) defenses:

Answer 4

Characteristics: antigen specific, has memory.

Question 5

Humoral immunity (and targets)

Answer 5

• antibodies present in fluids

- targets- bacteria, toxins, free viruses.

Question 6

Cell-mediated immunity (and targets)

Answer 6

• mediated by cells

- targets- cells, infected cells, cancer cells, transplant cells.

Question 7

Antigens

Answer 7

• Most foreign molecules, esp. proteins

- A “foreign” molecule which can invoke the immune response

Question 8

Cells of the immune system

Answer 8

• B cells

- T cells (LYMPHOCYTES)

Question 9

Lymphocytes

Answer 9

• Formed in bone marrow
• become immunocompetent in either the bone marrow (B) or thymus (T).
• This involves the acquisition of a specific antigen receptor. Then dispersal to the secondary lymphoid organs such as lymph nodes, spleen. (See Figure 20.8.)

Question 10

Humoral immune response

Answer 10

• activation of B cells by clonal selection.
• Antigen combines with surface receptor and stimulates the B cell to clone and develop into plasma cells and memory cells.
• Plasma cells secrete great amounts of antibodies that can combine with the antigen. -Memory cells result in a very rapid response for subsequent infections

Question 11

primary vs. secondary response

Answer 11

primary- occurs on first exposure to to a particular antigen.
-typically has a lag period of 3-6 days after the antigen challenge.

secondary- faster, more prolonged, and more effective b/c immune system has already been primed to antigen, and sensory memory cells are in place “on alert’.

Question 12

Cell-mediated immune response

Answer 12

Helper T cells stimulate T cell directed immune response

• cytotoxic T cells destroy infected or cancerous or foreign cells.
• Cytokines, such as the interleukins, are molecules that stimulate cells in the immune response.

Question 13

Helper T cells–Roles?

Answer 13

• stimulating other T cells and B cells that are specific for the invading antigen.
• They secrete various interleukins to stimulate T cells and B cells.
• Because of the need for this stimulation, the helper T cell is essential for immune system function.
• HIV, the AIDS virus, destroys this cell type and so destroys a person’s immune system.

Question 14

Cytotoxic T cells

Answer 14

• release of perforin to drill holes in target cells; then entrance of proteolytic enzymes (granzymes) that stimulate cell death (apoptosis).
• These T cells destroy virus-infected cells, cancer cells, and (unfortunately) transplanted organ cells.