Chapter 8: The Immune System

Question 1

Types of Immune System:

Answer 1

The immune system can be divided into innate and adaptive immunity.

Question 2

What is the innate immunity composed of:

Answer 2

The innate immunity is composed of defenses that are always active, but that cannot target a specific invader and cannot maintain immunologic memory; also called nonspecific immunity.

Question 3

What is the adaptive immunity composed of:

Answer 3

The adaptive immunity is composed of defenses that take time to activate, but that target a specific invader and can maintain immunologic memory; also called specific immunity.

Question 4

How is the immune system dispersed in the body:

Answer 4

The immune system is dispersed in the body. • Immune cells come from the bone marrow. • The spleen and lymph nodes are sites where immune responses can be mounted, and in which B-cells are activated. • The thymus is the site of T-cell maturation. Leukocytes, or white blood cells, are involved in immune defenses.

Question 5

The Innate Immune System have nonspecific defenses that are:

Answer 5

The Innate Immune System have nonspecific defenses are cellular and noncellular.

Question 6

NonSpecific Defenses that are noncellular:

Answer 6

This includes, the skin, mucus, tears + saliva, stomach, and interferons.

Question 7

The Skin:

Answer 7

Is a nonspecific defense that is noncellular because it acts as a physical barrier and secretes antimicrobial compounds, like defensins.

Question 8

c

Answer 8

Is a nonspecific defense that is noncellular because on mucous membranes it traps pathogens and in the respiratory system, the mucus is propelled upward by cilia and can be swallowed or expelled.

Question 9

Saliva + tears:

Answer 9

Non-cellular nonspecific defense that contains lysozyme, an antibacterial compound.

Question 10

Stomach:

Answer 10

Non-cellular nonspecific defense because it produces acid, killing most pathogens. Colonization of the gut helps prevent overgrowth by pathogenic bacteria through competition.

Question 11

Interferons:

Answer 11

Non-cellular nonspecific defense because it gives off by virally infected cells and help prevent viral replication and dispersion to nearby cells.

Question 12

Cellular NonSpecific Defenses:

Answer 12

This includes, macrophages, major histocompatibility complex (MHC) molecules class 1 +2, Dendritic cells, Natural killer cells, and Granulocytes.

Question 13

Macrophage:

Answer 13

Cellular Non-Specific Defense that ingest pathogens and present them on major histocompatibility complex (MHC) molecules. They also secrete cytokines.

Question 14

Major histocompatibility complex molecules: MHC Class 1

Answer 14

MHC class I (MHC-I) is present in all nucleated cells and displays endogenous antigen (proteins from within the cell) to cytotoxic T-cells (CD8+ cells).

Question 15

MHC Class 2:

Answer 15

MHC class II (MHC-II) is present in professional antigen-presenting cells (macrophages, dendritic cells, some B-cells, and certain activated epithelial cells) and displays exogenous antigen (proteins from outside the cell) to helper T-cells (CD4+ cells).

Question 16

Dendritic Cells:

Answer 16

Dendritic cells are antigen-presenting cells in the skin.

Question 17

Natural Killer Cells:

Answer 17

Natural killer cells attack cells not presenting MHC molecules, including virally infected cells and cancer cells.

Question 18

Granulocytes:

Answer 18

These include neutrophils, eosinophils, and basophils.

Question 19

Neutrophils:

Answer 19

Neutrophils ingest bacteria, particularly opsonized bacteria (those marked with antibodies). ○ They can follow bacteria using chemotaxis.

Question 20

Eosinophils:

Answer 20

Eosinophils are used in allergic reactions and invasive parasitic infections. ○ They release histamine, causing an inflammatory response.

Question 21

Basophils:

Answer 21

Basophils are used in allergic reactions. Mast cells are related cells found in the skin.

Question 22

The Adaptive Immune System:

Answer 22

Includes Humoral Immunity and Cell-mediated (cytotoxic) immunity.

Question 23

Humoral Immunity:

Answer 23

Humoral immunity is centered on antibody production by plasma cells, which are activated B-cells.

Question 24

Antibodies:

Answer 24

Are in humor immunity. These target a particular antigen. They contain two heavy chains and two light chains. ○ Constant region and a variable region; the tip of the variable region is the antigen-binding region.

Question 25

When antibodies are activated:

Answer 25

When activated, the antigen-binding region undergoes hypermutation to improve the specificity of the antibody produced. ○ Cells may be given signals to switch isotypes of antibody (IgM, IgD, IgG, IgE, IgA).

Question 26

Circulating Antibodies:

Answer 26

Circulating antibodies can opsonize pathogens (mark them for destruction), cause agglutination (clumping) into insoluble complexes that are ingested by phagocytes, or neutralize pathogens.

Question 27

Cell-surface Antibodies:

Answer 27

Cell-surface antibodies can activate immune cells or mediate allergic reactions.

Question 28

Memory B-Cells:

Answer 28

Memory B-cells lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response (secondary response).

Question 29

Cell-mediated (cytotoxic) immunity:

Answer 29

Cell-mediated (cytotoxic) immunity is centered on the functions of T-cells.

Question 30

T-cells:

Answer 30

• T-cells undergo maturation in the thymus through positive selection and negative selection. ○ The peptide hormone thymosin promotes T-cell development.

Question 31

Helper T-cells: Th1 Cell: Th2 Cell:

Answer 31

Helper T-cells (Th or CD4+) respond to antigen on MHC-II and coordinate the rest of the immune system, secreting lymphokines to activate various arms of immune defense. ○ Th1 cells secrete interferon gamma, which activates macrophages. ○ Th2 cells activate B-cells.

Question 32

Cytotoxic T-cells:

Answer 32

Cytotoxic T-cells (Tc, CTL, or CD8+) respond to antigen on MHC-I and kill virally infected cells.

Question 33

Suppressor (regulatory) T-cells:

Answer 33

Suppressor (regulatory) T-cells (Treg) tone down the immune response after an infection and promote self-tolerance.

Question 34

Memory T-cells:

Answer 34

Memory T-cells serve a similar function to memory B-cells.

Question 35

The Lympathic System:

Answer 35

This is a circulatory system that consists of one-way vessels with intermittent lymph nodes. • It connects to the cardiovascular system via the thoracic duct in the posterior chest. • It equalizes fluid distribution, transports fats and fat-soluble compounds in chylomicrons, and provides sites for mounting of immune responses.