Chapter 31 Terms and Ideas

Question 1

Innate immunity

Answer 1

nonspecific, used against many organisms:
• Includes barriers, such as skin and molecules toxic to invaders, as first line of defense.
• Second line of innate defenses includes phagocytic cells, which ingest foreign cells and other particles.
• These defenses may be present all the time or activated rapidly

Question 2

Adaptive immunity

Answer 2

• Distinguishes between substances produced by self and nonself.
• Involves antibody proteins and others that bind to and destroy pathogens.
• Slow to develop and long-lasting, found only in vertebrate animals

Question 3

Phagocytes

Answer 3

large cells that engulf pathogens and other substances by phagocytosis (i.e. macrophages)

Question 4

Lymphocytes

Answer 4

involve B cells and T cells, take part in adaptive immunity

Question 5

Antibodies

Answer 5

proteins that bind specifically to substances identified by the immune system. Antibodies are produced by B cells

Question 6

Major histocompatibility complex (MHC)

Answer 6

• MHC I proteins are found on most cell surfaces
• MHC II proteins are found on most immune system cells
MHC proteins are important self-identifying labels

Question 7

T cell receptors

Answer 7

integral membrane proteins on T cells, recognize and bind nonself molecules on other cells

Question 8

Cytokines

Answer 8

soluble signaling proteins that bind to a cell’s surface receptors and alter that cell’s behavior

Question 9

Normal Flora

Answer 9

the bacteria and fungi that usually live on body surfaces

Question 10

Mucus

Answer 10

secreted by mucous membranes. Mucus traps microorganisms so cilia can remove them.
Cilia continuously move the mucus plus debris up towards nose and mouth

Question 11

Lysozyme

Answer 11

an enzyme that attacks bacterial cell walls, is found in tears, nasal mucus, and saliva

Question 12

Defensins

Answer 12

peptides with hydrophobic domains that are toxic to many pathogens (produced by mucous membrane)

Question 13

Phagocytes

Answer 13

recognize pathogenic cells and ingest them by phagocytosis

Question 14

Natural killer cells

Answer 14

a type of lymphocyte that can detect virus-infected cells and some tumor cells:
• Can initiate apoptosis in these cells
• Can interact with the specific defense mechanisms and lyse cells labeled by antibodies

Question 15

Complement system

Answer 15

Proteins act in a cascade—each protein activates the next.
Provide three types of defense:
• Attach to microbes and mark them for phagocytes to engulf
• Activate inflammation response and attract phagocytes to site of infection
• Lyse invading cells

Question 16

Interferons

Answer 16

signaling molecules produced by cells infected by a pathogen.
Interferons increase resistance of neighboring cells to the pathogen by:
• Binding to receptors on noninfected cell membranes—stimulate a signaling pathway that inhibits viral reproduction
• Stimulating cells to hydrolyze pathogen’s proteins to peptides

Question 17

Inflammation

Answer 17

a coordinated response to injury—it isolates damage, recruits cells against pathogens, and promotes healing

Question 18

Mast cells

Answer 18

cells adhering to skin and organ linings; release chemical signals

Question 19

Mast cells chemical signals released

Answer 19

• Tumor necrosis factor—cytokine that kills target cells and activates immune cells
• Prostaglandins—initiate inflammation in nearby tissues, dilate blood vessels and interact with nerve endings, increasing sensitivity to pain
• Histamine—amino acid derivative that increases permeability of blood vessels so white blood cells can act on tissues

Question 20

Puss

Answer 20

Mixture of leaked fluid and dead cells

Question 21

Allergic reaction

Answer 21

a nonself molecule that is normally harmless binds to mast cells, causing the release of histamine and subsequent inflammation

Question 22

Autoimmune diseases

Answer 22

the immune system fails to distinguish between self and nonself, and attacks tissues in the organism’s own body

Question 23

Sepsis

Answer 23

the inflammation due to a bacterial infection does not remain local

Question 24

Specificity (Adaptive immunity)

Answer 24

T cell receptors and antibodies bind to specific nonself molecules (antigens).
Specific sites on the antigens are called antigenic determinants

Question 25

Diversity (Adaptive immunity)

Answer 25

The immune system must respond to a wide variety of pathogens by activating specific lymphocytes from a pool.
Diversity is generated primarily by DNA changes—chromosomal rearrangements and other mutations

Question 26

Clonal selection

Answer 26

a particular response is selected after the antigen binds to a specific T or B cell and the lymphocyte generates clones

Question 27

Clonal deletion

Answer 27

Any immature B and T cells that show the potential to mount an immune response to self antigens undergo apoptosis (non-working clones)

Question 28

Autoimmunity

Answer 28

failure of clonal deletion (destroys its own cells)

Question 29

Immunological memory

Answer 29

the immune system “remembers” a pathogen after the first encounter

Question 30

Primary immune response

Answer 30

when antigen is first encountered, “naïve” lymphocytes proliferate to produce two types of cells— effector and memory cells

Question 31

Effector cells

Answer 31

carry out the attack. Effector B cells (plasma cells) secrete antibodies. Effector T cells secrete cytokines and other molecules

Question 32

Memory cells

Answer 32

are long-lived cells that can divide on short notice to produce effector and more memory cells

Question 33

Secondary immune response

Answer 33

when antigen is encountered again, memory cells proliferate and launch an army of plasma cells and effector T cells

Question 34

Adaptive immune response phases

Answer 34

• Recognition phase—the organism discriminates between self and nonself to detect a pathogen.
• Activation phase—the recognition event leads to a mobilization of cells and molecules to fight the invader.
• Effector phase—the mobilized cells and molecules destroy the invader

Question 35

Humoral immune response

Answer 35

involves B cells that make antibodies

Question 36

Antigen-presenting cells

Answer 36

antigen is recognized by a T helper cell with a specific binding site

Question 37

Effector phase B cells versus T cells

Answer 37

B clone cells produce antibodies that bind to free antigen— results in inactivation and destruction of the antigen.
TC clone cells bind to cells bearing the antigen and destroy them

Question 38

Immunoglobulins

Answer 38

or antibodies, which contain a tetramer of four polypeptides
Two light chains and two heavy chains (disulfide bonds)
Each polypeptide has a constant region and a variable region

Question 39

Constant region

Answer 39

determines the general structure and function (the class) of an immunoglobulin

Question 40

Variable region

Answer 40

different for each specific immunoglobulin—responsible for antibody specificity

Question 41

Five classes of immunoglobulins

Answer 41

• IgG is secreted by B cells and constitutes about 80 percent of circulating antibodies.
• IgD is the cell surface receptor on a B cell.
• IgM is the initial surface and circulating antibody released by a B cell.
• IgA protects mucosa on epithelia exposed to the environment.
• IgE binds to mast cells and is involved with inflammation

Question 42

Terminal transferase

Answer 42

adds nucleotides before DNA is rejoined to create insertion mutations

Question 43

Cellular immune response (two types of T cells)

Answer 43

• T-helper cells (TH)- responds in activation of cellular immune response
• Cytotoxic T cells (TC)-responds in death of a cell carrying an antigen

Question 44

Class I MHC proteins

Answer 44

are present on the surface of every nucleated cell. They present antigens to TC cells

Question 45

Class II MHC proteins

Answer 45

on surfaces of macrophages, B cells, and dendritic cells—present antigens to TH cells

Question 46

Regulatory T Cells

Answer 46

Tregs recognize self antigens—when activated they release the cytokine interleukin 10.
This blocks T cell activation and leads to apoptosis of TC and TH cells bound to the same antigen