APII Exam 3 Study Guide

What is a pathogen?

A disease causing organism

Define immunity.

The ability to resist infection and disease

What is the compositional difference between lymph and plasma?

Lymph contains a much lower concentration of suspended proteins

Name the two primary lymph tissues/organs.

Red bone marrow and thymus

Name four secondary lymphoid tissues/organs.

Tonsils, MALT, lymph nodes, spleen

What is the function of lymphatic vessels?

Carry lymph from peripheral tissues to the venous system

Lymphatic capillaries have overlapping endothelial cells that act as one-way valves. Regarding pathogens, what is the importance of valves in immune function?

Prevents backflow

What feature do lymphatic vessels share with veins that allows lymph to flow in only one direction?

Valves

Define lymphedema.

Swelling because of lymphatic vessel obstruction

List two types of phagocytes associated with immune function.

Macrophages & microphages

List three classes of lymphocytes that circulate in blood.

T cells, B cells, NK cells

What are tonsils?

Lymphoid nodules in the walls of the pharynx

Which tonsils are usually inflamed when a patient experiences tonsillitis?

Palatine tonsils

What does the acronym MALT stand for?

Mucosa associated lymphoid tissue

Where is MALT located in the body?

The epithelia of the digestive, urinary, respiratory, and reproductive tracts

Lists three examples of MALT.

peyers patches, appendix, tonsils

Where are Peyer's patches located?

The epithelial lining of the intestine

What is the functional difference between afferent and efferent lymphatic vessels?

Afferent lymphatic vessels - bring lymph to the lymph node from peripheral tissues; Efferent lymphatic vessels - carry lymph away from the lymph node

Which cells located in the subcapsular space of a lymph node initiate the immune response?

Dendritic cells

What is the function of lymph nodes?

It purifies lymph before it reaches the veins

How are lymph nodes like early warning systems?

They monitor lymph with macrophages and lymphocytes for signs of trouble before it reaches vital organs.

What are thymosins and why are they important?

Thymic hormones that are important to the development and maintenance of T cells

List three functions of the spleen.

Removing other abnormal cells and other blood components by phagocytosis; Storing iron recycled from red blood cells; Initiating immune responses by B and T cells in response to antigens in circulating blood

both the lymph nodes and the spleen are sites for initiation of immune responses. The spleen detects foreign antigens in the blood and lymph nodes detect foreign antigens in the lymph, which is derived from interstitial fluid.

both the lymph nodes and the spleen are sites for initiation of immune responses. The spleen detects foreign antigens in the blood and lymph nodes detect foreign antigens in the lymph, which is derived from interstitial fluid.

State the difference between the spleen's red pulp and white pulp.

Red pulp contains large quantities of red blood cells, and white pulp contains lymphocytes

Why is innate immunity considered nonspecific?

It does not distinguish one potential threat from another

What lymphocytes are involved in innate immunity? What lymphocytes are involved in adaptive immunity?

Innate - NK cells; Adaptive - B cells and T cells

Define lymphocytopoiesis.

Lymphocyte formation

Where do B cells develop and mature?

Red bone marrow

Where do T cells develop and mature?

Thymus

Where do NK cells develop and mature?

Red bone marrow

Are first line defenses innate or adaptive?

Innate

True or False. If the statement is False, correct it. Adaptive immune defenses deny pathogens access to the body or destroy them without distinguishing among specific types.

False, innate immune defenses deny pathogens access

describe the function of the following innate defenses.

● Physical barriers

● Phagocytes

● Immune surveillance

● Interferons

● Complement

● Inflammation

● Fever

Physical barriers - keep hazardous organisms and materials outside; Phagocytes - engulf pathogens and cell debris; Immune surveillance - destruction of normal cells by NK cells; Interferons - chemical messengers against viral infections; Complement - assist antibodies; Inflammation - localized response; Fever - elevation of body temperature

Name two physical barriers.

Skin & mucous membrane

What two bactericidal molecules are found in sweat that reduce pathogen numbers on epidermal surfaces?

Lysozymes and antibodies

Name two kinds of microphages.

neutrophils & eosinophils

Give two examples of fixed macrophages.

Microglia & stellate macrophages (Kupffer cells)

What occurs during emigration?

Phagocytes attach to the endothelial lining and migrate to surrounding tissues

Define chemotaxis.

The attraction of phagocytic cells to the source of abnormal chemicals in fluids

What molecules are made and released after NK cell activation? What is their function?

Perforins; form pores in the target's membrane causing cell lysis

What are interferons?

small proteins released by activated lymphocytes and macrophages, and by tissue cells infected with viruses that slow viral replication and make other cells more resistant to viral infection.

What does a rise in levels of interferons suggest?

A virus

What proteins interact with one another in chain reactions known as cascades?

Complement proteins

How is the classical complement pathway activated?

C1 binds to antigen-tagged antibodies

How is the lectin complement pathway activated?

Binding of MBL to carbohydrates on pathogen surfaces

How is the alternative complement pathway activated?

Several complement proteins (factors) interact in the plasma

Complement activation using any of the three pathways produces three results. What are they?

Killing of pathogens (cell lysis); Enhanced phagocytosis (opsonization); Inflammation (histamine release)

What is a MAC complex and what is its function?

Membrane attack complex - destroys the integrity of the target cell

What is opsonization?

Enhanced phagocytosis when pathogens get "tagged" so immune cells can grab and destroy them more easily.

What specific chemical is released by mast cells and basophils that increases the degree of local Inflammation?

histamine

What are the four cardinal signs and symptoms of inflammation?

Redness, swelling, heat, and pain

Once neutrophils are activated, they undergo a respiratory burst. What two reactive chemicals do activated neutrophils produce? What is the outcome of their release?

Nitric oxide and hydrogen peroxide destroy engulfed pathogens

What is necrosis?

The tissue destruction that occurs after cells have been injured or destroyed

What is an abscess?

An accumulation of pus that in an enclosed tissue space

What are pyrogens? How do they work?

Fever-inducing agents that raise body temperature

List four main types of T cells and state their functions.

Cytotoxic T cells - attack antigens physically/chemically; Helper T cells - stimulate T and B cells; Regulatory T cells - moderate immune response; Memory T cells - respond to previously encountered antigen

What are stimulated B cells called? What do they secrete?

Plasma cells; produce and secrete antibodies

Define antigen.

A substance capable of inducing an immune response

What organic molecules comprise most antigens?

Proteins

What are three additional organic molecules that can act as antigens?

Lipids, polysaccharides, nucleic acids

True or False. If the statement is False, correct it. Clones of the same activated lymphocyte are sensitive to the same specific antigen.

True

Describe the four types of adaptive immunity and explain how the immunity is acquired.

Naturally acquired active (exposure in environment); Artificially acquired active (vaccination); Naturally acquired passive (maternal transfer); Artificially acquired passive (antibody administration)

What type of adaptive immunity occurs by contracting SARS-CoV-2, the causative agent of COVID-19, from your brother?

Naturally acquired active immunity

What form of adaptive immunity occurs when a person is vaccinated against SARS-CoV-2?

Artificially acquired active immunity

Patients who have COVID-19 can be treated with laboratory-produced antibodies against the SARS-CoV-2 spike protein. What type of adaptive immunity is this?

Artificially acquired passive immunity

Women who produced antibodies against SARS-CoV-2 while pregnant or from a previous exposure can transfer a certain isotype of antibody across the placenta to protect her unborn child. What type of adaptive immunity is this?

Naturally acquired passive immunity

Adaptive immunity is specific. What does this mean?

A specific defense is activated by a specific antigen, and the immune response targets that particular antigen and no others.

What is immune tolerance?

the ability of the immune system to ignore certain antigens instead of attacking them.

Define apoptosis.

Programmed cell death

What are APCs and what are their function?

Antigen presenting cells; activate T cell defenses against foreign cells and proteins

What are MHCs? What is another name they are known by?

Major histocompatability complexes or human leukocyte antigens

What is the importance of MHCs?

Identify cells as "self" and are used to display antigens to T cells

What must be recognized for antigen presentation to occur?

A specific antigen-MHC protein combination on a cell's plasma membrane

What blood group is considered the universal donor? Why?

Type O, all blood types can receive type O-

What blood group is considered the universal recipient? Why?

Type AB, type AB+ can receive all blood types

What do tissue typing tests determine?

How closely the donor and recipients HLA's match

What do cross matching tests determine?

Compatibility between donor and recipient blood

Which cells have MHC Class 1 proteins?

All nucleated cells

What triggers antigen presentation by class I MHC proteins?

Viral or bacterial infection of a body cell

What triggers antigen presentation by class II MHC proteins?

Phagocytics APC's engulf extracellular pathogens

Which cells have MHC Class II proteins?

Antigen-presenting cells and lymphocytes

List three examples of phagocytic antigen-presenting cells.

free/fixed macrophages, stellate macrophages, microglia

Name one example of non-phagocytic antigen-presenting cells. Where are they found?

Dendritic cells; found in the skin, lymph nodes, and spleen

Which cells have CD8 markers? Antigen bound to which MHC class do they detect?

Cytotoxic and regulatory T cells; class I MHC

Which cells have CD4 markers? Antigen bound to which MHC class do they detect?

Helper T cells; class II MHC

What is costimulation and what is its function?

Prevents T cells from attacking "self"; helps determine when a T cell will become activated

What is the function of regulatory T cells?

Moderate the responses of other T and B cells by secreting suppressor factors

What molecules are produced by T helper cells that function to coordinate specific and nonspecific defenses and stimulate cell-mediated and antibody-mediated immunities.

Cytokines

A sensitized B cell does not undergo activation unless it receives the "OK" from which type of cell?

Helper T cell

What are the two pairs of polypeptide chains of a Y-shaped antibody molecule called?

Heavy chains and light chains

The specificity of an antibody molecule depends on the amino acid sequence of which region of the antibody?

Variable segments

Antibodies bind to specific portions of an antigen's exposed surface. What are these antigenic determinant sites called?

Epitopes

What is a hapten?

A partial antigen

Which antibody type is most prevalent in the body and is the only antibody class that can cross the placenta?

IgG

Which antibody is important in allergic responses?

IgE

Which antibody is the first to be secreted the first time an antigen is encountered?

IgM

Which antibody has five antibody molecules connected to form a starburst shape?

IgM

Blood typing utilizes agglutination reactions using anti-A and anti-B. What class of antibody are anti-A and anti-B?

IgM

Which antibody is found in body secretion such as tears and saliva and can have a structure of two connected antibodies with a secretory molecule?

IgA