A&P Chapter 21: Part 2

Name the 2 arms of adaptive immunity and their targets

Humoral immunity- B cells target extracellular pathogens
Cellular immunity- T cells target cells that have become infected by bacteria and viruses, cancer cells, and foreign cells

Name the four key characteristics of the adaptive immune system

Mediated by lymphocytes
Very specific in contrast to innate defenses
Systemic, affects whole body
Form memory cells

Define antigen

Antigen- molecules (proteins, glycoproteins) found on surface of cells that mobilizes our adaptive defense that mobilizes antibodies

Define complete antigen, hapten (incomplete antigen), and antigenic determinant

Complete antigen- antigens that have immunogenicity (proliferation of lymphocytes) and reactivity (ability to react with lymphocytes and antibodies)
Hapten- small molecule that can link with proteins and cause an attack from immune system
Antigenic determ

Describe the origin and maturation location of B and T lymphocytes

Both originate in bone marrow
B Lymphocytes- stay in bone marrow and mature
T Lymphocytes- mature in thymus

How and where do lymphocytes become activated

When a lymphocyte's antigen receptors bind its antigen, that lymphocyte can be activated

Fill in the gap: T-lymphocytes can only bind to antigens that are presented to them on_______ proteins.


During maturation, lymphocytes become immunocompetent and self-tolerant. Define immunocompetence and self-tolerance

Immunocompetence- Ability of lymphocyte to bind to antigen
Self-Tolerance- The lymphocyte cannot bind to its own antigen

Name 3 types of antigen-presenting cells and describe their location and role

Dendritic cells- found in frontline defense (skin), once they internalize pathogens, they will travel to lymph nodes
Macrophages- found in lymphoid organs (medulla, connective tissue), present antigens to T-cells for activation and can also become activat

Define humoral immunity.

Humoral Immunity- involves b-cells which develop into plasma cells which secrete antibodies

Describe the process of clonal selection.

B-cells with different attached antibodies can detect different antigens. B-cells will wait in lymph node and once it encounters an antigen, it will start dividing and develop into plasma cells. Plasma cells secrete antibodies, and the antigen will determ

State the roles of plasma cells and memory cells in humoral immunity

Some B-cells will develop into memory cells. In the future, if body encounters same pathogen, memory cells will detect pathogens and respond faster and stronger to the pathogen. Forms thousands of plasma cells which will secrete many more antibodies.

Compare and contrast naturally/artificially active and passive humoral immunity. Which one develops memory cells

� Naturally Acquired- Infection, contact with pathogen
� Artificially Acquired- Vaccine, dead or attenuated pathogens
� Naturally Acquired- Antibodies passed from mother to fetus via placenta, or infant in milk
� Artificially Acquired- In

Describe the structure of antibodies

Structure: 4 polypeptides: 2 Heavy chain variable regions, 2 Light chain variable regions, 2 Heavy chain constant regions, 2 light chain constant regions, and one stem region. Polypeptides connected by disulfide bonds.

Describe the functions of antibodies

� Neutralization- antibodies bind to pathogens so virus cannot bind to corresponding receptors
� Agglutination- antibodies form a complex with cells which will be eliminated through phagocytosis
� Precipitation- complex between antibodies and antigens whi

Name the five antibody classes and describe where they occur?

IgM- find on b-cells as monomer, but pentamer is found in blood plasma
IgA- find in body secretions (sweat, saliva)
IgD- found on b-cell surface
IgG- most abundant in plasma
IgE- find in skin and mucosa of GI tract and respiratory tract

Define cellular immune response

Composed of:
Cytotoxic T-cells- attack cellular targets and eliminate them
Helper T-cells- regulate immune system by release of chemicals

The APC (dendritic cells) present antigens to T-cells and activate them. How and where are the antigens presented to T-cells?

Presented with help of MHC II proteins on CD4 cells and MHC I on CD8 cells
1. Antigen Presentation- dendritic cell engulfs exogenous antigen, displays its fragments on class II MHC protein
2. Double Recognition- CD4 T cell recognizes MHC complex and binds

Chemokines are the chemical messengers of the immune system. Which cells secreted IL-2 and is the chemokine Interleukin -2 (IL-2), and what is its function?

Secreted by helper t-cell, travels to and activates CD8, and activates b-cells

Describe the roles of different types of T cells

Helper T-cells- directly interact and activate B-cell, can also activate CD8 cell (indirect)
Regulatory T-cells- dampen immune response and prevent autoimmune reactions
Cytotoxic T-cells- attack virus and pathogen infected cells, cancer cells, and foreign

How do cytotoxic T cells attack infected and cancerous cells?

� Cytotoxic T-cell binds to target cell
� Cytotoxic T-cell releases perforin and granzyme molecules from its granules by exocytosis
� Perforin molecules insert into the target cell membrane and form transmembrane pores
� Granzymes enter the target cell vi