Micro Final

Platelets

Broken off portions of cells that circulate in the bloodstream and help blood clot

Lymphocytes

Agranular, round cells with large nuclei commonly found in lymphoid organs

Eosinophils

Motile, granular cells that help destroy eukaryotic pathogens

Macrophages

Large phagocytic cells that clean up cellular debris and pathogens

Mast cells

A nonmotile cell that produces chemokines for recruitment of immune cells.

B Cells

These lymphocytes mature in the bone marrow

Megakaryocytes

Very large cells that slough off portions that aid with blood clotting

Cytotoxic T Cells

These lymphocytes destroy target cells via MHC I/antigen-dependent lysis

Leukocytes

White blood cells

T-reg Helper Cells

Lymphocytes that regulate and decrease immune responses as needed.

Basophils

Motile, granular cells aiding allergic responses and inflammation

Dendritic Cells

Phagocytic cells with long projections for pathogen capture

Plasma Cells

Formed after B-cell activation; produce antibiodies

T-H1 Helper Cells

Lymphocytes that activate CD4 and CD8 cells

Neutrophils

Phagocytic, motile granular first responders at inflammation sites

Erythroctes

Red blood cells

T-H2 Helper Cells

Lymphocytes that activate B cells and lead to B-cell proliferation

T-H17 Helper Cells

Lymphocytes that promote inflammation

Monocytes

Agranular, round cells circulating in blood that can differentiate into macrophages or dendritic cells

Neutral Killer Cells (NK)

These cells do not process antigens, but are capable of killing infected or cancerous body cells

Compare and contrast innate/natural defenses and adaptive immunities. Of the 3 lines of defense discussed, which are innate and which are adaptive?

• Innate defenses: present at birth, provide nonspecific resistance to infection

• Adaptive immunities: specific, must be acquired

• First- Innate

• Second- Innate

• third- Adaptive

Explain the main function of each of the lines of defense.

• First: Surface protection; any barrier that blocks invasion at the portal of entry

• Second: protective cells and fluids on the inside of the body

• Third: Acquired with exposure to foreign substances/pathogens and forms memory

What are the 4 categories of nonspecific defenses in the 1st line of defense?

• Physical barriers

• Chemical barriers

• Genetic Resistance

• Microbiome

Give several examples of physical and chemical defenses and describe how they defend against pathogens.

Physical-

• Skin: inhibit microbial growth, sweat

• Mucous Membranes: traps microbes, flushing

Chemical-

• Digestive tract- hydrochloric acid

• Antimicrobial peptides

Describe the role of antimicrobial peptides and give examples.

A specific class of broad-spectrum antimicrobial mediators, nonspecific. Some are produced routinely by the body others are produced in response to presence of invading pathogens

• Bacteriocins

• Cathelicidin

• Defensins

• Dermicidin

How does genetic variation play a role in immune response? Include examples in your explanation.

Small genetic differences in susceptibility exist for other pathogens. Viruses have great specificity for their host receptors

Describe the role of microbiota as a first-line defense against infection and disease.

Compete with pathogens for cellular binding sites and nutrients

What is the primary goal of the immune system?

1. Surveillance of the body

2. Recognition and differentiation of the normal versus foreign material

3. Attack and destroy entities deemed to be foreign

Platelets serve what role during an injury?

Blood clotting

Explain how lymph is formed, what lymph transports and the overall role of the lymphatic system.

• Formed when blood components move out of the blood vessels into extracellular spaces

• Transports WBC, fats, cellular debris, and infectious agents

• Provides and auxiliary route for return of extracellular fluid to the circulatory system

• acts as a drain-off system for the inflammatory response

• Renders surveillance, recognition, and protection against foreign material

Where do WBCs examine and filter lymph for possible foreign materials?

Lymph nodes

Differentiate between the primary and secondary lymphoid organs and describe their purposes.

Primary-

• Bone marrow- where all blood cells are made and b-cells mature

• Thymus- high rate of growth and activity until puberty, then begins to shrink, t-cell maturation

Secondary-

• Lymph nodes- WBC filtration

• Spleen- filters circulating blood to remove worn out RBC and pathogens

Define and differentiate between cytokines and chemokines. What is a cytokine storm?

Cytokines- a chemical substance produced by the WBC and tissue cells that regulates development, inflammation, and immunity -signaling molecule

Chemokines- (type of cytokine) Chemical mediators that stimulate the movement and migration of WBC

Cytokine Storm- BAD, body causes a big storm of several types of cytokines, overwhelming

What is the primary purpose of interferons?

Tells cells to stop replicating when infected- Cytokine produced by WBC and tissue cels with antiviral activity

What induces monocytes to become a macrophage or dendritic cell?

a signal that something is wrong and then leaving the bloodstream

Name and describe the process of how a WBC exits a blood vessel and what properties are required that allow them to survey tissues.

Diapedesis (Extravasation)-

1. They are motile amoeboid cells that move by means of pseudopods

2. They can crawl along the surfaces of blood vessels and can change shape

3. They are programmed to respond to inflammatory signals

What are the 4 symptoms of inflammation?

Redness, Warmth, swelling, and pain

Describe the major inflammatory events that occur after a splinter injury.

1. Injury/immediate reactions- blood vessels narrow, blood clots, mast cells release chemokines and cytokines into injured area

2. Vascular Reactions- nearby blood vessels dilate, increased blood flow and vascular permeability, increased leakage of fluid forms exudate

3. Edema and pus formation- collection of fluid, edema/swelling, infiltration by neutrophils and formation of pus

4. Resolution/scar formation- macrophages, lymphocytes, and fibroblasts migrate in, initiate immune response and repair of injury, scar and loss of normal tissue

What causes a fever and what are 3 benefits of a fever?

Initiated by circulating pyrogens that cause the hypothalamus to release prostaglandins that triggers muscles to increase heat production and vasoconstriction.

1. Raises body temperature above optimum growth of pathogens

2. inactivates some microbial enzymes and toxins

3. makes you feel ill and more likely to rest

4. Increases the rate of chemical reactions in your body, starving microbes from certain resources like iron

What purpose do phagocytes serve as a second-line of defense?

Engulf something and get rid of it

What does PAMP stand for? What is a PAMP used for? Give examples of PAMPs.

Pathogen Associated Molecular Patterns - something pathogen has/produces that we don’t

What is a pattern recognition receptor?

Receptors on WBC for PAMPs

Explain how a macrophage recognizes a pathogen and the process of phagocytosis.

Toll-like receptors bind to PAMPs, detect foreign molecules and signal the macrophage to produce chemicals to stimulate an immune response

1. Chemotaxis

2. Binding

3. Ingestion

4. Phagolysosome formation

5. Destruction

6. Elimination

In what 3 ways can complement aid in destroying bacteria and viruses?

1. Stimulates inflammation

2. Opsonization: tag bacteria to be engulfed by immune system

3. Destroy via membrane attack complex

What are the main 2 goals of the adaptive defenses?

1. Specificity- antibodies produced function only against the antigen that they were produced in response to

2. Memory- lymphocytes produced function to “recall” their first encounter with an antigen and respond rapidly to subsequent encounters

Explain the purpose of MHC class I and class II molecules.

Class 1- genes encode for markers that display unique characteristics of self and allow recognition of self molecules and regulation of immune reactions.

Class 2- genes code for immune regulatory receptors found on antigen-presenting cells (APCs)

What is required by a molecule to be considered an antigen?

Substance that elicits immune response in specific lymphocytes

antigenicity

What is an epitope?

Antigenic determinants- small molecular group recognized by lymphocytes

Give examples of both good and bad immunogens. What makes a molecule a good/bad immunogen?

Capable of producing an immune response (essential in vaccine development)

• Big

• foreign

• stable

• complex

What is special about the antigenicity of haptens?

carrier group contributes to the size of the complex and enhances the orientation of the antigen, while the hapten serves as the epitope

Allloantigens

Cell surfaces markers and molecules that occur in some members of the same species but not in others

Explain the theory of clonal selection in detail.

1. One stem cell can produce many lymphocytes that all undergo gene rearrangement to make their receptors

2. each cell has a particular/unique receptor specifcity

Why is a white blood cell count a useful tool to detect the presence of infection?

Tells how many immune cells are circulating your system. More cells =more infection being fought

Compare and contrast Helper T cells vs. Cytotoxic T cells.

T-helper assist in immune response regulation

T-Cytotoxic kill pathogens

What cell types can serve as antigen-presenting cells and which one is the most common?

1. Macrophages

2. Dendritic cells (most common)

3. B cells

What determines whether a Helper T cell turns into a TH1 cell or a TH2 cell?

Depends on what set of cytokines is released from APCs

Why are superantigens a deadly virulence factor?

provoke overwhelming immune responses by large numbers of T cells regardless of specificity

How do B cells detect antigens?

detect free antigens

What are immunoglobulins and how do they develop unique antigen-binding sites?

Large glycoproteins that serve as specific receptors of B cells and as antibodies

variable regions

Describe the process of a B-cell going from naïve to fully activated.

1. Recognize the antigen

2. Bind to the B-cell receptor

3. Internalize the antigen through endocytosis

4. Present the antigen

5. Interact with the T-cell

6. co-stimulation and activation signal

Explain the immediate events after B-cell activation & the two possible cell-types that are produced.

Plasma and memory

Why is the presence/absence of antibodies in your body not the best method to discern immune status?

Does not give a full picture of the immune system

List and explain the 3 main antibody-antigen interactions.

1. Neutralization

2. opsonization

3. agglutination

What aspect of adaptive immunity provides the robust secondary response to a pathogen?

Formation of memory cells

Differentiate between all 4 types of immunity and give examples.

1. Active

2. Passive

3. Innate

4. Adaptive

Explain why killed cells or inactivated virus vaccines may require boosters whereas live, attenuated vaccines do not.

killed vaccines do not create as strong of an immune response. This is good for people with weak immune systems but also means that immunity does not last as long

Why do acellular, subunit, and recombinant vaccines give reduced antigenicity?

the smaller the antigen, the less epitopes resulting in decreased antigenicity.

Why do some vaccines require an adjuvant?

The adjuvant increases the immune system’s response to the vaccine

Describe how an mRNA vaccine works.

mRNA for the antigen is injected into the recipient. The mRNA is then replicated by dendritic cells and passed to t-cells. T-cells show b-cells and b-cells create memory and plasma cells

What features of mRNA allow it to be minimally invasive as a vaccine?

mRNA does not enter the nucleus and therefore will not interfer with the host DNA

Differentiate between intrinsic and extrinsic factors and explain how they influence microbial growth?

Intrinsic factors are characteristics of the organism itself while extrinsic factors are characteristics of the environment

What are the methods of microbial control in food? What are the methods applied using temperature?

Heating: Pasteurization, boiling

Cold: Refrigerating, freezing

Moisture: drying

Radiation: irradiation

How water availability influences microbial growth?

Microorganisms require water to grow

What types of food are most likely to be irradiated? Why?

Meat, fresh fruit and veggies. Prevent foodborne illness, preservation, etc.

What are the two primary types of food borne disease and how are they transmitted?

Infectious and Intoxications

Superantigens

potent T cell stimulators

Allergens

antigens that evoke allergic reactions

Autoantigens

molecules on self-tissues for which tolerance is inadequate