Biology 8: The Immune System

Question 1

innate immunity

Answer 1

composed of defenses always active against infection

lack ability to target specific invaders over others - nonspecific

includes…

• skin, respiratory, GI tract
• monocytes/macrophages, granulocytes, NK cells, mast cells, dendritic cells
• complements, interferons
  *

Question 2

adaptive immunity

Answer 2

defenses that target a specific pathogen - specific immunity

slower system, maintains memory for faster later

includes. ..
* B-cells and T-cells

Question 3

location of blood storage and activation of B-cells

Answer 3

spleen

Question 4

B-cells

Answer 4

leukocyte made in the bone marrow

naive cells leave and enter the spleen until activation

once activated turn into plasma cells that produce antibodies

plays a major role in humoral immunity (in the blood)

Question 5

small gland in front of pericardium

maturation site of T-cells

Answer 5

thymus

Question 6

T-cells

Answer 6

lymphocytes that mature in the bone marrow and migrate to thymus to mature

coordinate the immune system, directly kill virally infected cells

important in cell-mediated immunity

Question 7

lymph nodes

Answer 7

parts of the lymphatic system that filter lymph

a site where immune responses can be mounted

Question 8

skin (integument)

Answer 8

first defense; acts as a physical barrier

secretes antimicrobial compounds like defensins (antibacterial enzymes) and sweat

Question 9

complement system

Answer 9

consists of proteins in the blood that act as a nonspecific defense against bacteria

can be activated through a classical pathway (with antibodies) or an alternate pathway (no antibodies)

punches holes in the cell walls of bacteria

Question 10

Langerhans cell

Answer 10

resident populations of macrophages in the skin

Question 11

microglia

Answer 11

resident populations of macrophages in the CNS

Question 12

osteoclasts

Answer 12

resident populations of macrophages in bone

Question 13

macrophage

Answer 13

cell involved in nonspecific immunity that…

1. Phagocytizes invader through endocytosis
2. digests invader using enzymes
3. presents pieces (peptides) of the invader to other cells using MHC

also secrete cytokines

are not lymphocytes - but are leukocytes

Question 14

major histocompatibility complex

Answer 14

molecules that bind to pathogenic peptide (antigen) and carries to macrophage cell surface to be recognized by other cells in adaptive system

Question 15

MHC class I

Answer 15

present in all nucleated cells

displays endogenous antigen (proteins from inside the cell) - endogenous pathway

allows immune system to monitor the health of the cell

binds to cytotoxic T-cells (CD8+ cells)

Question 16

MHC class II

Answer 16

present in all professional antigen-presenting cells (macrophages, dendritic cells, B cells)

displays exogenous antigens (proteins from outside) - exogenous pathway

binds to helper T-cells (CD4+ cells)

Question 17

pattern recognition receptors

Answer 17

receptors that recognize the category of the invader and allows for the appropriate cytokines to recruit the correct response

Question 18

natural killer cells

Answer 18

nonspecific lymphocyte

able to detect the downregulation of MHC accomplished by viruses or cancer

induce apoptosis

Question 19

neutrophils

Answer 19

the most populous leukocyte in blood, short-lived

phagocytic granulocytes that target bacteria using chemotaxis secreted or through opsonization

dead collections = pus

Question 20

eosinophils

Answer 20

granulocyte involved in allergic reactions and parasitic infections

release histamine to mediate inflammation -> vasodilation to allow immune cells to leave blood into tissue

Question 21

basophils

Answer 21

granulocytes involved in allergic responses

least populous leukocyte

Question 22

mast cell

Answer 22

cell similar to basophils but with smaller granules

exist in tissues, mucosa, epithelium, skin - not in lymph

Question 23

opsonization

Answer 23

the binding of a specific antigen to an antibody, which attracts other leukocytes to phagocytize the antigen immediately

Question 24

things that happen when an antibody binds to an antigen in body fluids

Answer 24

1. opsonization
2. agglutination
3. neutralization (blocking ability to invade tissues)

Question 25

primary response

Answer 25

**initial activation** of a B-cell upon exposure to the correct antigen B-cell responds by proliferating and producing **plasma cells** and **memory B cells**

Question 26

secondary response

Answer 26

occurs when a microbe activates a B cell **for the second time** **memory cells** act to produce antibodies specific to the pathogen more rapid and robust

Question 27

positive selection

Answer 27

maturation pattern of T-cells in the thymus that involves only selecting for cells that can react to antigen presented on MHC

Question 28

negative selection

Answer 28

maturation pattern in the thymus that involves causing apoptosis in cells that are activated by proteins produced by the organism itself (self-reactive)

Question 29

thymosin

Answer 29

peptide hormone secreted by the thymic cells facilitates the maturation of T-cells

Question 30

types of T-cells

Answer 30

**helper** T-cells - **CD4+** **suppressor** T-cells - **regulatory** T-cells - **CD4+** and **Foxp3+** **cytotoxic** T-cells - **CD8+**

Question 31

helper T cells

Answer 31

**CD4+** secrete **lymphokines** that recruit other cells respond to **MHCII** - exogenous antigens - **bacterial, fungal, parasitic infections**

Question 32

cytotoxic T-cells

Answer 32

**CD8+** **directly kill** virally infected cells by injecting chemicals that promote apoptosis respond to **MHCI** - endogenous antigens - **viral, intracellular bacterial, intracellular fungal**

Question 33

suppressor T-cells

Answer 33

**CD4+ Foxp3+** help **tone down** the immune response once infection has been contained turn off self-reactive lymphocytes to prevent autoimmune disease - **self-tolerance**

Question 34

interferons

Answer 34

proteins that prevent viral replication and dispersion cause nearby cells to decrease production of both viral and cellular proteins decrease the cell permeability upregulate MHC I and II molecule production for better detection

Question 35

lacteals

Answer 35

small lymphatic vessels in center of each **villus** in the small intestine **fats** are packaged into **chylomicron**s, enter here for transport to circulatory system

Question 36

clonal selection

Answer 36

adaptive immune system encounters an antigen, and cells with receptors specific to that antigen are activated and proliferated