Microbiology Exam 3

What purposes does inflammation serve?

- Acute inflammation is an organism's response a harmful stimulus, which could be a physical injury, an allergic reaction, or another cause. - The inflammation itself is due to increased blood flow to the area, which brings with it plasma proteins (like fibrinogen, which helps clot a wound) and leukocytes (white blood cells, which attempt to remove the stimulus).

What are the roles of hemolysins, leukocidins, and lecithinase in bacterial pathogenesis?

- Hemolysins: Make holes in the plasma membrane of red blood cells - Leukocidins: Make holes in the plasma membrane of white blood cells - Lecithinase: Exotoxin that cleaves phospholipids

What is the major role of chemicals released by damaged and immune cells?

- Histamine: Vasodilation (increased permeability of blood vessels), released from mast cells, basophils and platelets - Kinins: Vasodilation, attraction of neutrophils - Prostaglandins: Intensify histamine and kinin effect - Leukotrienes: Vasodilation, phagocytic attachment to pathogens, released from the mast cells and basophiles

What methods do pathogens use to survive during phagocytosis?

- Inhibit adherence: M protein, capsules - Kill phagocytes by causing the release of the phagocyte's own lysosomal enzymes: Staphylococcal leucocidins - Escape from phagosomes - Prevent phagosome - lysosome fusion - Survive in phagolysosome - Lyse the membranes of phagolysosome and phagocytes

What are the roles of the primary lymphoid organs and the secondary lymphoid organs?

- Primary: They provide an environment for stem cells to divide and mature into B- and T- cells - Secondary: Filter out pathogens and maintain the population of mature lymphocytes

What causes the redness, swelling, and pain associated with inflammation?

- Redness: Vasodilation - Pain: Increase permeability and causes edema - Swelling: Plasma proteins and leukocytes

How is fever beneficial?

- inhibits multiplication of temperature-sensitive pathogens. - increases immune activity by increasing IL-1 activity. - produces antiviral interferon. - limits available iron to pathogens by increasing transferrins. - speeds up tissue repair.

What is the role of T helper cells in immunity?

-helper T cells produce cytokines + differentiate into:>TH1: produce IFN-gamma (activates cells related to cell-med. immunity, stimulate production of antibod.)>TH2: activate eosinophils to produce IgE>TH17: stimulate innate immune system>TF: follicular helper T cells, stimulate B cells to produce plasma cells>memory cells

Exotoxins are divided into three principal types on the basis of their structure and function. What are those?

1. A-B toxins 2. membrane-disrupting toxins 3. Superantigens

How is the classical pathway activated?

1. C1 is activated by binding to antigen-antibody complexes 2. Activated C1 splits C2 into C2a and C2b, and C4 into C4a and C4b 3. C2a and C4b combine and activate C3, splitting it into C3a and C3b

Explain the process of inflammation

1. Chemicals such as histamine, kinins, prostaglandins, leukotrienes, and cytokines are released by damaged cells 2. Blood clot forms 3. Abscess starts to form 4. Margination - phagocytes stick to endothelium 5. Diapedesis - phagocytes squeeze between endothelial cells 6. Phagocytosis of invading bacteria occurs

What are the phases of phagocytosis?

1. Chemotaxis and adherence of phagocyte to microbe 2. Ingestion of microbe by phagocyte 3. Formation of phagosome (phagocytic vesicle) 4. Fusion of phagosome with a lysosome to form a phagolysosome 5. Digestion of ingested microbes by enzymes in the phagolysosome 6. Formation of the residual body containing indigestible material

What are the four ways pathogens damage host cells?

1. by consuming the host's nutrients 2. by causing direct damage 3. by producing toxins 4. by inducing hypersensitivity (allergy) reactions

How do CTLs kill virus infected host cells?

1. virus infected cell produces abnormal endogenous antigens2. abnormal antigen presented on surface in association w/ MHC class I molecules>CD8+ T cells w/ receptors for antigen transformed into CTLs3. CTL induces destruction of virus infected cell by apoptosis>destruction caused by perforin (makes pore on cell surface) + granzyme (triggers programmed cell death called apoptosis)

What is the valence of IgM antibodies?

10, pentamer + monomers connected by disulfide bonds

How many classes of antibodies are produced in the body and what are they?

5 IgG IgM IgA IgD IgE

A typical antibody monomer has: A. two identical light chains and two identical heavy chains. B. two different light chains and two different heavy chains. C. two identical light chains and two different heavy chains. D. two different light chains and two identical heavy chains.

A

Edema is defined as a collection of fluid in an area of the body. What is the physiological change that causes edema? (MM) A. Increased permeability of blood vessels B. Constriction of blood vessels C. Fever D. Activation of complement

A

Endotoxic shock can result from using antibiotics to treat A. gram-negative bacterial infections. B. fungal infections. C. viral infections. D. protozoan infections.

A

Fixed macrophages that are found in the lungs are called A. alveolar macrophages B. microglial cells C. Kupffer's cells D. peritoneal macrophages

A

IgG antibodies inactivate microbes by blocking their attachment to host cells in the binding process, and this antibody function is known as A. Neutralization B. Aggulation C. Antibody- dependent cell-mediated cytotoxicity D. Opsonization

A

Margination? A. accumulation and adhesion of leukocytes to the epithelial cells of blood vessel walls at the site of injury. B. the passage of white blood cells through the intact walls of the capillaries. C. cells pass between the blood circulatory system and the lymphatic system. D. a localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful.

A

One disease that can be transmitted by the parenteral route is A. Tetanus B. Trachoma C. Influenza D. Tuberculosis

A

Plasma cells are formed after the proliferation of which type of cell? A. B cells B. T cells C. Natural killer cells D. Monocytes

A

The antibody that is formed in the secondary response is mostly A. IgG B. IgE C. IgM D. IgA

A

The high temperature in a fever increases the production of A. Transferrins B. Leukotrienes C. Lectins D. Siderophores

A

What is the action of botulinum toxin? A. Inhibition of muscle contraction B. Activation of muscle contraction C. Inhibition of muscle relaxation D. Activation of muscle relaxation

A

When pathogens enter the skin, they usually A. enter through the hair follicles and sweat ducts. B. penetrate intact skin. C. are injected into the skin. D. adhere to the skin and then penetrate the skin.

A

Which complement pathway is activated by antibodies bound on the surface of bacteria and fungi? A. Classical Pathway B. Alternative pathway C. Lectin pathway D. Opsonization pathway

A

Which hormone is produced by the endotoxin and causes fever? A. Prostaglandins B. Estrogen C. Insulin D. Aldosterone

A

Which of the following is classified as an agranulocyte? A. Monocyte B. Neutrophil C. Eosinophil D. Basophil

A

Which one is not a first line of defense in innate immunity? A. Fever B. Lacrimal apparatus C. Ciliary escalator D. low pH of gastric juice

A

Which pathogen has a different portal of entry than others? A. A pathogen causing diarrhea B. A pathogen causing pneumonia C. A pathogen causing sore throat D. A pathogen causing flu or cold

A

When m/os cause skin infections, they usually enter the skin through _____________.

A break in the skin

What are MHC proteins?

A coding region for surface proteins and they are major antigen barriers for tissue transplantation as well as present antigens to leukocytes

What is syncytium?

A giant cell

What is the complement?

A group of serum proteins involved in phagocytosis and lysis of bacteria. the complement system is a defensive system consisting of over 30 proteins produced by the liver and found circulating in blood serum and within tissues throughout the body. A group of serum proteins involved in phagocytosis and lysis of bacteria. the complement system is a defensive system consisting of over 30 proteins produced by the liver and found circulating in blood serum and within tissues throughout the body.

Which type of immunity, active or passive, lasts longer? Why?

Active immunity because it takes time and creates memory

Is vaccination an example of innate or adaptive immunity?

Adaptive

What is the role of adaptive immunity and how is it different from that of innate immunity?

Adaptive is something that is induced resistance to a pathogen and innate is natural

What bacterial molecules are used to bind to their host cells?

Adhesins

How do endotoxins cause fever during infections?

After Gram-negative bacteria are ingested by phagocytes, the bacteria are degraded in vacuoles, and the LPSs of the bacterial cell wall are released. These endotoxins cause the white blood cells, macrophages, to produce cytokines called interleukin-1 (IL-1), formerly called endogenous pyrogen, and tumor necrosis factor alpha (TNF-α). The cytokines are carried via the blood to the hypothalamus, a temperature control center in the brain. The cytokines induce the hypothalamus to release lipids called prostaglandins, which reset the thermostat in the hypothalamus at a higher temperature. The result is a fever.

How do antibodies inactivate or kill microorganisms and toxins?

Agglutination Opsonization Activation of complement Antibody-dependent cell-mediated cytotoxicity Neutralization

Why do IFN-α and IFN-β share the same receptor on target cells, yet IFN-γ has a different receptor?

Alpha and beta are produced by virus-infected cellsInduce unaffected cell to produce mRNA, Gamma produced by lymphocytes induce neutrophils and macrophages

How does cholera toxin work and what is the result?

Another A-B toxin from which many people suffer is cholera toxin produced by the Gram-negative bacterium Vibrio cholerae. Cholera toxin affects the function of intestines, so it is an enterotoxin. Cholera toxin is constituted with one A subunit and five B subunits. The B subunits bind specifically with a complex glycolipid called the ganglioside GM1 in the cytoplasmic membrane of epithelial cells. Then the A subunit crosses the cell membrane and activates adenyl cyclase that converts ATP to cyclic AMP (cAMP). Higher cAMP levels cause secretion of chloride and bicarbonate ions from mucosal cells into the intestinal lumen. This results in the secretion of large amounts of water into the lumen. The rate of water loss into the small intestine can be greater than the reabsorption of water by the large intestine, so massive net fluid loss caused by diarrhea occurs. Victims generally die from dehydration and electrolyte imbalance. Treatment of cholera is oral fluid replacement with solutions containing electrolytes and other solutes.

Which part of an antibody reacts with the epitope of an antigen?

Antigen binding site interacts w/ cognate antigen

What is the role of TLRs in phagocytosis?

Attach to pathogen-associated molecular patterns on microbes.

( ) on the surface of phagocytic white blood cells such as macrophages interact with ( ) of microbial pathogens to recognize that they are foreign cells. A. PAMP - TLR B. TLR - PAMP C. PAMP - PRM D. PAMP - Adhesin

B

All gram-negative bacteria contain A. Exotoxins B. Endotoxins C. Siderophores D. igA protease

B

Bacterial surface molecules involved in attachment to the host tissue are called A. Receptors B. Adhesins C. Evasins D. Virulence

B

Clostridium tetani causes the disease tetanus by producing a(n) A. endotoxin B. exotoxin C. capsule D. enzyme

B

Coughing is a portal of exit for the A. Urinary Tract infection B. Pneumonia C. AIDS D. Herpes simplex

B

Cytotoxic T lymphocytes attach to the target cell and release A. lysozymes B. granzyme and perforin C. complement proteins D. antibodies

B

Endotoxins are lipopolysaccharides A. produced by viruses. B. produced by only Gram-negative bacteria. C. produced by any kind of bacteria. D. produced by only Gram-positive bacteria.

B

How many antigen-binding sites do most human antibodies have? A. 1 B. 2 C. 4 D. 5

B

Lacrimal apparatus protects _________ against infection. A. Ears B. Eyes C. Noses D. Lungs

B

Receptors on human cells that recognize various common bacterial substances such as peptidoglycan are: A. PAMPs B. Toll-like Receptors C. Adhesins D. Ligands

B

The bacterial surface proteins used to enter inside host cells are A. Adhesins B. Invasins C. Spikes D. Ligands

B

The stem of the Y-shaped antibody monomer is called the ____ region. A. Constant B. Fc C. Variable D. Active

B

What inhibits cell wall synthesis or forms pores in the bacterial plasma membrane?A. Phagocytes B. Antimicrobial peptides C. Iron-binding proteins D. Interferons

B

What is correct about A-B toxins? A.) Toxin B is activated by A. B.) B delivers toxin A by binding to a receptor. C.) Toxin A is activated by enzyme B. D.) A-B toxins are all neurotoxins.

B

What is the activation and proliferation of specific B cells termed? A. Plasma cell selection B. Plasma cell expansion C. Clonal selection D. Memory cell formation

B

When plasma leaves the blood vessels and functions to bathe the tissues, it is called... A. Intercellular plasma B. Interstitial fluid C. Lymph D. Lymphoid fluid

B

Which antigen-presenting cells play a key role in helping your immune system differentiate self from nonself? A. neutrophils B. dendritic Cells C. memory cells D. plasma cells

B

Which antimicrobial peptide do sweat glands produce? A. defensin B. dermcidin C. cathelicidin D. thrombocidin

B

Which is not a benefit to bacteria by lysogenic conversion? A. Bacteria get immunity to similar types of phages. B. Bacteria get more nutrients using phage enzymes. C. Some medically important bacteria acquire toxins for successful infection. D. None of the above are true.

B

Which of the following diseases utilizes the respiratory tract as its portal of entry? A. Hepatitis B. Influenza C. Cholera D. Tetanus

B

Which one is not an A-B toxin? A. diphtheria toxin B. erythrogenic toxin C. botulinum toxin D. cholera toxin

B

Which portal of entry is most often used by microorganisms? A. Parenteral route B. Mucous membranes of the respiratory route C. Mucous membranes of the conjunctiva D. Skin

B

Which portal of entry is most often used by microorganisms? A. parenteral route B. mucous membranes of the respiratory route C. mucous membranes of the conjunctiva D. skin

B

What are roles of B cells?

B cells mature in bone marrow, contact with an antigen through B cell receptor, and activated to plasma cells and produce antibodies

What is the role of invasins in bacterial pathogenesis?

Bacterial proteins to be used to enter inside a host cell

How does increased amount of iron binding proteins inhibit bacterial growth?

Because many bacteria require iron for normal growth

How can lysogeny turn the normally harmless E. coli into a pathogen?

Because some prophages contribute to the pathogenicity of the host bacteria by providing toxin production

Why do bacterial infections cause fever?

Because your body is trying to kill the virus or bacteria that caused the infection

Where are B cells and T cells born, differentiated, and situated (stored)?

Both are bone in bone marrow, B cells differentiated in adult red bone marrow, T cells differentiated in thymus. Both stored in lymphoid tissues such as spleen and especially lymph nodes

What is one of the most potent biological toxins on the Earth?

Botulinum toxin

How does M protein work to avoid phagocytosis?

By binding to human plasma proteins and prevents phagocytosis

How does SLO lyse only host cells?

By forming channels in the plasma membrane of host cells

A toxoid, such as the tetanus toxoid, conveys _____ immunity. A. naturally acquired active B. naturally acquired passive C. artificially acquired active D. artificially acquired passive

C

A. Inhibition of muscle contraction. B. Activation of muscle contraction. C. Inhibition of muscle relaxation D. Activation of muscle relaxation

C

Bacterial siderophores A. Inhibit host's protein synthesis B. Are neurotoxins C. Steal host cell's iron molecules D. Synthesize vitamins

C

Generally, antibodies recognize and interact with specific regions on antigens called A. Binding sites B. Haptens C. Epitopes D. Active sites

C

In opsonization, antigens that are coated with antibodies are susceptible to A. B cells B. Natural killer cells C. Phagocytosis D. Inflammation

C

Interferons are produced by certain animal cells after being stimulated by A. Protozoa B. Bacteria C. Viruses D. Fungi

C

Maturation of the T cells takes place in the A. Bone Marrow B. Liver C. Thymus D. Spleen

C

Neisseria gonorrhoeae produces what to attach on and invade into host white blood cells? A. M protein B. Dextran C. Opa protein D. Fimbriae or pili

C

Some prophages contribute to the pathogenicity of the host bacteria by providing toxins production. This phenomenon is called A. Toxin transformation B. Phage transformation C. Phage conversion D. Lysogenic transduction

C

The lectin pathway of complement is activated by: A. Antibodies bound on microbial cell surfaces B. Certain lipid-carbohydrate complex on microbial cell surfaces C. Carbohydrate containing mannose on microbial cell surfaces D. Flagella proteins on microbial cell surface

C

The passage of white blood cells through the intact walls of the blood vessels is A. Margination B. Inflammation C. Diapedesis D. Intravasation

C

The so-called Hillary escalator functions A. Moving microbes towards the lower respiratory tract B. Killing microbes C. Moving microbes toward the throat D. Moving microbes from the nose

C

The so-called ciliary escalator functions A. moving microbes towards the lower respiratory tract. B. killing microbes. C. moving microbes toward the throat. D. moving microbes from the nose.

C

What is the role of streptokinase? Streptokinase is involved in A. coagulating fibrinogen. B. hydrolyzing hyaluronic acid. C. Breaking down fibrin. D. breaking down collagen.

C

Which antigen-presenting cells play a key role in helping your immune system differentiate self from nonself? A. neutrophils B. dendritic cells C. memory cells D. plasma cells

C

Which enzyme is responsible for making space between the cells of a tissue for further spread of the pathogen? A. Coagulase B. Streptokinase C. Hyaluronidase D. Collagenase

C

Which of these if a disadvantage of fever ? (CQ) A. Increased IL-1 B. Increased interferon C. tachycardia D. Increased transferrin production

C

Which one is NOT a function of the lymphatic system? A. To return the extracellular fluid to the blood circulatory system. B. To render surveillance, recognition and protection against foreign materials. C. To house red blood cells. D. To drain off extra fluid by the inflammatory response.

C

Which one is correct about A-B toxins? A. The B subunit is recruited by the A subunit B. All A-B toxins are hemolysins C. The A subunit is the toxin portion D. The A subunit delivers the B subunit

C

Which one is false? Botulinum toxin A. Is produced by clostridium botulinum B. Is a neurotoxin C. Inhibits muscle relaxation D. Causes death by suffocation

C

Which one is not a lymphoid organ? A. Thymus B. Spleen C. Liver D. Tonsil

C

Which one is not an exotoxin? A. Superantigen B. A-B toxin C. Lipid A D. Hemolysin

C

Which one is not the characteristic of exotoxins? A. Most of them are proteins. B. They can be neutralized by antitoxins. C. They usually cause fever. D. They are secreted outside of microbial cells.

C

Are dendritic cells considered primarily part of the humoral or the cellular immune system?

Cellular

Identify chemical factors that prevent microbes from entering the body through skin and mucous membranes.

Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.

What is clonal deletion, clonal selection and clonal expansion and when do they occur?

Clonal selection is B cell complexes w/ its specific antigen + proliferates. B cell III binds to cognate antigen. Clonal expansion is the process of B cells proliferating + differentiating into antibody producing plasma cells

What is the role of coagulase in bacterial pathogenesis?

Coagulase is a bacterial enzyme triggering blood clot formation. When pathogens invade a host tissue, nearby blood vessels leak to provide the blood plasma containing nutrients and immune factors such as white blood cells to remove pathogens and recover the damage caused by pathogens

How are antibody subunits connected to each other?

Connected by disulfide bonds (indicated as S-S-S)

How does the lacrimal apparatus protect the eyes against infections?

Continual washing prevents microbes from setting on surface of the eye, excess tears dilute and wash away the irritating substance or microorganisms

What is the function of cytokines?

Controlling the growth and activity of other immune system cells and blood cells/ -chemical messengers-soluble proteins or glycoproteins -produced by practically all cells of immune system in response to stimulus

What are the roles of Fc?

Crystallizable fragment, has sites interacting w/ other immune factors such as phagocytes + complement

( ) on the surface of phagocytic white blood cells interacts with ( ) of microbial pathogens to recognize that the pathogens are foreign cells (CQ) A. PAMP - TLR B. TLR - PAMP C. PAMP - PRR D. TLR - PRR

D

During inflammation, there is activation and increased concentration of a group of proteins causing vasodilation in the blood called A. transferrin's B. Hormones C. Prostaglandins D. Acute-phase proteins

D

Inflammation? A. Accumulation and adhesion of leukocytes to the epithelial cells of blood vessel walls at the site of injury B. The passage of white blood cells through the intact walls of the capillaries C. Cells pass between the blood circulatory system and the lymphatic system D. A localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful

D

Most antigens are composed of A. Proteins or lipids B. Lipids or large polysaccharides C. Nucleic acids or lipids D. Proteins or large polysaccharides

D

Some bacteria evade the complement system by means of their A. Endospores B. Flagella C. Cilia D. Capsules

D

The most numerous white blood cells, that have multilobed nuclei and are very phagocytic are A. Lymphocytes B. Monocytes C. BasophilsD. Neutrophils

D

What type of immunity is conveyed when infected individuals are given antibodies such as anti-venom antibody or anti-Ebola antibody by injection? A. naturally acquired active B. naturally acquired passive C. artificially acquired active D. artificially acquired passive

D

Where are MHC II proteins found, and what cells recognize them? A. Almost all body cells; Neutrophils B. Almost all body cells; T cells C. Some white blood cells; Neutrophils D. Some white blood cells; T cells

D

Which exotoxin directly disturbs our immune system by binding to the surface of immune cells to make us sick? A. Lipid A of gram-negative cells B. A-B toxin C. Hemolysin D. Superantigen

D

Which host defense is more effective against gram-positive bacteria than gram-negative bacteria? A. Mucus B. Sebum C. Gastric juice D. Lysozyme

D

Which of the following bacteria neutralizes stomach acid, allowing the bacterium to grow in the stomach? A. Clostridium botulinum B. Streptococcus mutans C. Streptococcus pyogenes D. Helicobacter pylori

D

Which of the following is NOT part of the body's first line of defense? A. Skin B. Mucous membranes C. Saliva D. Fever

D

Which one below is not an advantage of being intracellular pathogens? A. They can get nutrients easily. B. They can avoid white blood cells effectively. C. They can move into deeper tissues. D. They can produce toxin more easily.

D

Which one is NOT a benefit of fever? A. It inhibits multiplication of temperature-sensitive pathogens. B. It stimulates immune reactions. C. It reduces available iron to microbes. D. It inactivates bacterial toxins.

D

Which statement is true of endotoxins? (MM) A. They are proteins B. They are disease specific C. They are produced by gram-positive bacteria D. They are released upon cell lysis

D

Which virulence factors are not involved in avoiding or overcome the host immune system? A.) S. pyogenes M protein B.) N. gonorrhoeae Opa protein C.) M. tuberculosis Mycolic acid D.) C. botulinum toxin

D

What leukocytes are antigen presenting cells?

Dendritic cells, activated macrophages and B cells

What antimicrobial peptides are produced by human cells?

Dermcidin, defensins, cathelicidins, and thrombocidin

What makes a natural killer cell, which is not immunologically specific, attack a particular target cell?

Destroy cells that don't express much MHC I. They don't require activation, kill virus-infected and tumor cells, which are often missing MHC antigens. Self vs. non-self-discrimination: kills things that aren't self.

What is the clonal deletion of lymphocytes and when and where does it occur?

Eliminates harmful B cells and T cells, occurs during maturation of B cells in bone marrow and T cells in thymus

What are the definitions of exotoxins and endotoxins?

Exotoxin: Toxic substances released outside the cell Endotoxin: Toxins composed of lipids that are part of the cell membrane

What are the characteristics of exotoxins?

Exotoxins are secreted toxins by mostly Gram-positive and some Gram-negative bacteria. Most of them are proteins, and many are enzymes. Many exotoxins bind to host molecules and change their function. The genes for exotoxins are carried usually by plasmids or phages.

Which part of antibodies attracts phagocytes and complement?

Fc portion attracts + interacts w/ phagocytes + complement (opsonization) opsonization: tagging microbes to attract phagocytes

What is the function of lymph nodes?

Filter substances that travel through the lymphatic fluid

Which bacterial cell surface appendage is used to bind to host tissues?

Fimbriae

How does streptokinase dissolve the blood clot?

First, streptokinase or staphylokinase binds with plasminogen and forms the activator complex. This activator complex cleaves free plasminogen in the blood and converts to plasmin that cleaves fibrin, the main component of the blood clot.

What kinds of macrophages exist in the body?

Fixed and wandering

What does the lymphatic capillary collect?

Fluid from your body's cells and tissues to filter.

What properties give better antigenicity?

Foreignness, size, shape, accessibility

What happens when inflammation occurs?

Four signs and symptoms: Redness, swelling (edema), pain, heat

List three portals of entry, and describe how microorganisms gain access through each

GI tract: Should overcome stomach acid, bile, and etc.. Genitourinary tract: Portal of STD. Skin: Openings in the skin, such as hair follicles and sweat gland ducts

What molecules are used as adhesins?

Glycocalyx, Fimbriae and M protein

What are the roles of T helper cells T cytotoxic cells?

Helper cells: Binds to antigen produced by infected cells. Cytotoxic: Causes molecules to kill infected host and reject foreign tissues

What type of cells is most associated with humoral immunity, and what type of cells is the basis of cellular immunity?

Humoral - B-cells, Cellular - T cells

What is the role of hyaluronidase in bacterial pathogenesis?

Hyaluronic acid is a material to cement cells, so located between cells. When some pathogens penetrate epithelial cells in the skin or mucosal membranes, they produce an enzyme called hyaluronidase that degrades hyaluronic acid to invade into deeper tissues.

Many bacterial products are used for medical purposes. In the case of the disease shown in the picture (Blocked coronary artery (thrombosis)), what bacterial product can be used?

If thrombosis occurs in the coronary arteries that are the main blood vessels in the heart, then it causes heart attack. Since streptokinase can dissolve blood clots, one of the treatments for heart attack is to inject streptokinase into a vein.

What antibody is the primary one produced when an antigen is taken up by an M cell?

IgA

Which antibody is found in mucosal membranes?

IgA

Which antibody is the B cell receptor?

IgD

Which antibody is involved in allergic reactions?

IgE antibody

Which antibodies activate the complement system?

IgG + IgM

Which antibody protects fetus and newborns?

IgG antibodies

§ Which antibodies are usually associated with agglutination?

IgM

How do antimicrobial peptides kill bacteria?

Inhibiting cell wall synthesis, destroying the plasma membrane, or destroying the DNA and RNA

How do bacterial pathogens evade the complement attack?

Inhibiting the attachment of complement components and enzymatic digestion of C5a Gram (+) cocci

What is the role of Botox?

Inhibits muscle contraction

Which defense system, innate or adaptive immunity, prevents entry of microbes into the body?

Innate

Distinguish between innate immunity and adaptive immunity.

Innate immunity is defenses against any pathogen, while adaptive immunity is immunity or resistance to a specific pathogen

What is the purpose of keratin in the epidermis?

It is a protective protein

How does the natural killer cell respond if the target cell does not have MHC class I molecules on its surface?

It kills the cell by causing pores to form in it

How does the lectin pathway differ from the classical pathway?

Lectin begins with C2 and never touches C1 and also does not split as much

What is the chemical nature of the endotoxin, is it a protein, lipid, or carbohydrate?

Lipid

Which molecule is the endotoxin and which bacteria, Gram negatives or positives, have it?

Lipid A of lipopolysaccharides is the endotoxin, and it is in the Gram-negative outer membrane

What is the function of M cells and where are they located?

M (microfold) cells: used by pathogens to enter GI or respiratory tracts-located of Peyer's patches (secondary lymphoid organs located on intestinal wall)-antibodies, mostly IgA, formed here + migrate to mucosal lining

What components are in the lymph?

Made up of water, dissolved salts, and 2-5% proteins

Identify physical factors that prevent microbes from entering the body through skin and mucous membranes.

Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body.

Distinguish microbial antagonism from commensalism.

Microbial antagonism: in this relationship the normal microbiota helps the host and prevents the growth of harmful microbes; Commensalism: this is a type of relationship, where one organism is benefited, and the host is unaffected. The microbes utilize the food and environmental resources of the host for their survival, but the microbes are harmless to the host until it is in specified environmental conditions.

Compare the structures and function of monocytes and neutrophils.

Monocyte: precursor to macrophage, swelling of lymph nodes during infection. neutrophil: highly phagocytic and motile, active in initial stage of infection, destroy foreign MO's and particles

How many molecules consist of the complement system?

More than 30

· Which are the most common portals of exit?

Mucous membrane, skin, parenteral route

What are the similarities and differences between NK cells and CTLs?

NK cells: granular leukocytes, destroy cells that don't express MHC I>kill virus infected + tumor cells, attack parasites-unlike CTLs, not immunologically specific (don't need to be stimulated by antigen)

Which white blood cell is most predominant in the blood?

Neutrophils

What are the roles of neutrophils and macrophages?

Neutrophils are the first defense phagocytes in infection sites and react early to microbes, foreign materials & damaged tissue. Macrophages scavenge and process foreign substances to prepare them for reactions with B and T lymphocytes

Would pneumococcal pneumonia require a TH cell to stimulate a B cell to form antibodies?

No, the polysaccharides of the bacteria would be enough to elicit B cell activation

How are B cells activated?

Occurs by binding to specific antigen leading to clonal selection + expansion

How does Opa protein work to avoid host immune attack?

Opa-mediated internalization of Neisseria by neutrophils that is a type of white blood cells. Opa protein of Neisseria interacts with the host cell surface receptor CEACAM3. CEACAM3-binding Opa proteins recruit more receptor molecules to the site of adherence. Receptor ligation by Opa (O) produces a signal that causes internalization of Neisseria into host cells.

What is inclusion body?

Particles of aggregated protein

What is the role of siderophores in infection?

Pathogens secrete siderophores to obtain iron (for survival)Compete with iron-binding proteins by binding more tightly

What are four mechanisms or components in the second line of defense?

Phagocytes, inflammation, fever, antimicrobial substances

What is the function of plasma cells and memory cells?

Plasma cells: dedicated to producing antibodies while memory cells do not, they are just active B cells.

What are the roles of interferons?

Produce antiviral proteins that inhibit viral replication and activate neutrophils and macrophages to kill bacteria and tumor cells

What is phage conversion?

Prophage DNA is incorporated in the host DNA and changes the characteristics of the host bacteria

What is the role of the lymphatic system?

Protects your body against foreign invaders: The lymphatic system is part of the immune system. It produces and releases lymphocytes (white blood cells) and other immune cells that monitor and then destroy the foreign invaders

What is the molecular nature of exotoxins, proteins, lipids, or carbohydrates?

Protein

Which one is more antigenic, proteins or lipids? Why?

Proteins because they are more complex which makes them more antigenic

What is the role of the lymphatic system in immunity?

Renders surveillance, recognitions, and protection against foreign materials

What happens if ciliary escalator is inhibited?

Respiratory tract infections, increases chances of pathogen descending into lungs resulting in pneumonia

How does streptolysin O disrupt red blood cells?

SLO binds to cholesterol in the host plasma membrane and oligomerizes on the surface of the membrane making a prepore complex. Then the prepore complex inserts into the plasma membrane and makes a hole.

What are septic shock and what causes septic shock?

Shock refers to any life-threatening decrease in blood pressure. Shock caused by bacteria is called septic shock

What is the role of streptokinase and staphylokinase in bacterial pathogenesis?

Some pathogens produce an enzyme that triggers dissolving blood clots such as streptokinase or staphylokinase to spread themselves to other tissues.

Which microorganism (m/o) uses dextran as an adhesin?

Streptococcus mutans

M protein is used as an adhesin by what m/o?

Streptococcus pyogenes

What pathogens use capsules to prevent phagocytosis?

Streptococcus pyogenes, Streptococcus pneumoniae, Klepsiella pneumonia, Haemophilus influenzae

If we kill normal microbiota by using a broad-spectrum antibiotic, then what could happen?

Superinfection

Which T cell type is generally involved when a B cell reacts with an antigen and produces antibodies against the antigen?

T Cytotoxic: recognizes endogenous antigens on the target's cell surface that are combined w/ MHC

What is the main difference between B cell immunity and T cell immunity?

T cell immunity against intracellular pathogens; B cell immunity against freely circulating microbes (where antibodies contact them)-T cells respond to antigens by T-cell receptors (TCRs); B cells have coating of immunoglobulins that provide specificity -recognition of antigens by T-cells requires antigen presenting cells (APCs)

Which is the T cell type that is generally involved in allergic reactions?

T helper cells: interact with an antigen before B cells interact with the antigen; specifically, TH2 cells, produce IgE antibodies

What is the definition of T-dependent antigens and what are examples?

T-dependent: antigen that requires helper T cells for antibody production. antigen presented w/ MHC protein bind to helper T cells. helper T cell produces cytokines that activate B cell

What relationship do Toll-like receptors have to pathogen-associated molecular patterns?

TLRs on human cells recognize various common bacterial PAMPs such as peptidoglycan, LPS, flagellin, and so on.

What is the name of tetanus toxin and how does it work?

Tetanospasmin: Tetanus toxin is also an A-B toxin and moves through motor neurons to the spinal cord and binds specifically to ganglioside lipids at the nerve endings of the inhibitory interneurons. Tetanus toxin blocks glycine release by inhibitory interneuron, leading to continual release of acetylcholine and uncontrolled contraction of the poisoned muscles. Tetanus toxin also causes paralysis, which is called spastic paralysis because of muscle contraction all the time. If tetanus is not treated, the final result is also death by suffocation.

What is antibody valence?

The # of antigen binding sites.

What is the definition of A-B toxins?

The A component has toxic activity, and the B component has the binding activity to the host cell receptor

How does the botulinum toxin work?

The A-B toxin Botulinum toxin binds at the nerve endings of the stimulatory motor neurons at the neuromuscular junction and blocks the release of the neurotransmitter acetylcholine, so botulinum toxin-poisoned muscle cannot receive an excitatory signal resulting in no muscle contraction. The result of botulinum toxin poisoning is paralysis. Since muscle contraction is impaired, this kind of paralysis is called flaccid paralysis. If we cannot control muscle movements, the first critical trouble we will have is breathing, so if botulinum toxin poisoning is not treated, the final result is death by suffocation.

What are the roles of the A component and B component in A-B toxins?

The B (binding) component of exotoxin attaches to the host cell receptor. The A-B exotoxin enters the host cell by receptor-mediated endocytosis. The A-B exotoxin is enclosed in a pinched-off portion of plasma membrane called the endosome. Inside the endosome, the A-B components of exotoxin separate. Then the A component alters cell function by inhibiting protein synthesis whereas the B component is released from the host cell.

What benefits do bacteria earn through phage conversion?

The bacterial cell is immune to infection by the same type of phage.

Why are bacterial capsules medically important?

The capsule is considered a virulence factor because it enhances the ability of bacteria to cause disease

How does the complement system aid in fighting infections?

The complement system is made up of a large number of distinct plasma proteins that react with one another to opsonize pathogens and induce a series of inflammatory responses that help to fight infection

What is the difference between antigens and epitopes?

The epitope is an antigenic determinant that is antibody binding sites on antigens. Antigens are components of the cell wall and carries more than one epitope

What is phagocytosis and what cells do perform this?

The ingestion of microbes or particles by a cell, performed by phagocytes

How is the alternative pathway different from the classical pathway?

The main difference between classical and alternative pathway is that the initiation of alternative pathways is not dependent on the presence of immune complexes.

How is a hapten different from antigens?

The molecule is too small to stimulate antibody formation by itself. It is not antigenic by itself, but some people develop allergic reaction to it.

Low pH of the skin and mucous membrane prevents infection. Why?

The skin and mucous membranes also create a chemical environment that is hostile to many microorganisms. The surface of the skin is acidic, which prevents bacterial growth. Saliva, mucus, and the tears of the eye contain an enzyme that breaks down bacterial cell walls.

Define cytopathic effect

The visible effects of viral infection

Why is ADCC important protection against parasitic protozoa and helminths?

These parasites are too large to be phagocytized

Where are lymphatic capillaries in the body and what force makes the lymphatic fluid flow?

They are all over the body except the CNS, bone, placenta, and thymus. The movement and contraction of muscles help it flow.

How are microorganisms destroyed during phagocytosis?

They are digested

What function do capsules and M proteins have in common?

They both add to a bacteria's virulence

How can toxoids prevent microbial infections?

They can no longer cause disease but can still stimulate the body to produce antibodies

What is the role of CTLs?

They play a major role in host defense against viral infection, as well as infection by other intracellular pathogens that replicate in the cytoplasm of the host cell.

What triggers inflammation?

Tissue damage

What is the outcome of clonal selection?

To generate a clonal cell population that eliminates the antigen

What is the role of collagenase in bacterial pathogenesis?

To invade the skin, some pathogens produce collagenase that is a collagen-degrading enzyme.

How is the degree of pathogen's virulence generally measured?

To measure the degree of virulence of pathogens or toxins, two terms, ID50 and LD50 are mostly used. ID50 is for pathogens to cause disease and LD50 is for toxins. ID50 is the # of microbes (infectious dose) to cause disease to 50% of a test population

What is the function of superantigens in bacterial pathogenesis?

To provoke a very intense immune response

What is the signaling mechanism for muscle relaxation?

To relax the contracted muscles, the CNS signals to inhibitory interneurons, then the inhibitory interneuron secretes the inhibitory neurotransmitter glycine. When the secreted glycine binds to the receptors on the surface of motor neurons, the binding makes the motor neurons stop the release of acetylcholine and promote recollection of acetylcholine, so inhibits muscle contraction, allowing relaxation.

How does toxigenicity differ from direct damage?

Toxigenicity is the ability to produce a toxin and direct damage is damage directly.

What are the benefits for microorganisms to grow inside host cells?

Viruses easily evade host defenses because components of the immune system cannot reach

Why do both human hosts and pathogens need iron for living and how do pathogens steal host's iron?

We need iron for growth, but normally we can have enough iron by eating meat and using iron utensils. Iron is also required for the growth of most pathogenic bacteria. However, the concentration of free iron in the human body is fairly low because most of the iron is tightly bound to iron-transport or storage proteins, such as lactoferrin, transferrin, and ferritin, as well as hemoglobin. To obtain free iron, some pathogens secrete proteins called siderophores. When a pathogen needs iron, siderophores are released into the medium, where they take the iron away from iron transport proteins by binding the iron even more tightly. Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface. Then the iron is brought into the bacterium.

What is extravasation?

When blood components move out of blood vessels into extracellular spaces

What is the signaling mechanism for muscle contraction?

When excitation signals for muscle contraction from the central nervous system arrive at the motor neurons close to muscles, the nerve ending of motor neurons secrete the neurotransmitter called acetylcholine, and acetylcholine binds to the receptor on the muscle surface. Then the muscle cells contract.

Why do lymph nodes swell during an infection?

Your lymph nodes get larger when more blood cells come to fight off an invading infection. They all essentially pile in, causing pressure and swelling. Often, the lymph nodes that swell will be close to the infection's site.

What is the function of siderophores and what produces them?

a molecule which binds and transports iron in microorganisms, pathogens produce them

What is apoptosis and how does it occur?

apoptosis: suicide system, or programmed cell death-if cells sick + not repairable, suicide program triggered-can be triggered intrinsically or extrinsically

How does E. coli cause membrane ruffling?

as E. coli, Shigella, Salmonella and Neisseria gonorrhoeae produce proteins called invasins to induce endocytosis of host cells. These bacterial invasins change the host cell cytoskeleton network to be internalized inside the host cell. The figure shows that the invasin protein of Salmonella triggers host cell membrane ruffling that pulls the bacterium inside.

How do pathogens damage host cells directly?

as the pathogens use the host cell for nutrients and produce waste products. Some bacteria can also penetrate host cells by excreting enzymes and by their own motility; such penetration can itself damage the host cell.

How do capsules help bacteria avoid phagocytosis?

capsules make bacterial surface components more slippery, helping the bacterium to escape engulfment by phagocytic cells.

What is the role of antigen presenting cells?

critical for the initiation of adaptive immune responses and for maintenance of peripheral tolerance. APCs are strategically positioned as immune sentinels ready to respond to invading pathogens in peripheral tissues.

What is cytokine storm and what can cause it?

cytokine storm: when feedback loop gets out of control, resulting in harmful overproduction of cytokines-causes:>toxins (especially endotoxin) --> septic shock>superantigen

What is the action of lysozyme?

damages or kills bacteria by lysing their cell wall peptidoglycan, by disrupting bacterial membranes, and by activating autolytic enzymes in the bacterial cell wall.

How are T helper cells activated?

dendritic cells important in activation of CD4+ cells-to be activated, it's TCR recognizes an antigen that has been processed + is presented as a complex w/ MHC class II proteins on surface of APC-initial signal for activation

What do fixed and wandering macrophages do?

fixed macrophages: resident in certain tissues and organs. Ex: liver, lungs, nervous system, spleen, lymph nodes, red bone marrow. Wandering macrophages: roam tissues and gather at sites of infection or inflammation.

What is the role of T regulatory cells?

formally called T suppressor cells-Treg cells: CD4 + CD25 on surface-function: combat autoimmunity by suppressing T cells against self

What cells are involved in cell-mediated immunity and what are their functions?

helper T cell: activates cell mediated immunity (macrophages, cytotoxic t cells)-cytotoxic t lymphocyte: destroys target cells on contact-activated macrophage: enhanced phagocytic activity; attacks cancer cells-natural killer cell: attacks + destroys target cells

How are intracellular pathogens recognized by the immune system?

in normal cells, MHC I contain "self-peptides"-if cells infected w/ intracellular pathogens, MHC I of those express viral peptides-they are then targeted for destruction by cytotoxic T lymphocytes

AVPs degrade viral mRNA and inhibit protein synthesis - and thus interfere with viral replication

it stimulates the infected cells and those nearby to produce proteins that prevent the virus from replicating within them

How is neutralization different from agglutination?

neutralization: when antibodies cover infectious agents (viruses, bacteria, toxins), blocks ability of binding to their targets (inhibition of adherence or adhesion). agglutination gathers infectious agents, neutralization interferes w/ adherence of infectious agents to target cells or molecules

What is the difference between the primary and secondary immune responses regarding antibody titers and response time?

primary: long lag period, low amount of titer, secondary: faster and more effective

What is the role of the MHC II molecules?

receptor on helper T cell recognizes MHC Class II, activates + produces cytokines (which activate B cell). B cells begin clonal expansion

Is the anamnestic response primary or secondary?

secondary

How does the agglutination by antibodies help get rid of antigens?

since antibodies have at least two antigen-binding sites, can link a group of microbes. antibodies can connect to hundreds of microbes this way (agglutination). agglutination can immobilize motile microbes + reduces number of infectious units to be dealt with

How are antibodies involved in killing large cells such as helminths?

some antibodies on helminths attract WBCs (macrophages, NK cells, eosinophils). after being attracted, WBCs can secrete toxic proteins to kill large eukaryotic target cells (antibody-dependent cell-mediated cytotoxicity) -antibody-dependent cell-mediated cytotoxicity tags large parasites (ex. roundworms, tapeworms)

Distinguish pathogenesis, pathogenicity, and virulence.

the mechanism or process to cause disease is called pathogenesis. Pathogenicity: The ability to cause diseases. Virulence: The extent or degree of pathogenicity

What are the functions of inflammation?

to destroy the injurious agent, or to limit the effects by confining the injurious agent; to repair or replace tissue damaged by the injurious agent.

What is the ciliary escalator?

transports microbes trapped in mucus away from the lungs

Intracellular pathogens such as Listeria, Shigella, and Coxiella burnetii, how do they spread one host cell to another?

use a host cytoskeleton material called actin to move inside host cells and invade neighboring cells.

How do superantigens screw up our immune system?

when T helper cells recognize antigens on MHC II molecules, T helper cells activated + produce cytokines-this interaction should be brief to produce adequate amount of cytokines-superantigens make interaction too long>connect TCR + MHC II, T helper cells produce too much cytokine, can lead to cytokine storm

How does mycolic acid work to resist host immune attack?

· Resists digestion by phagocytes · Has strong "armor" · Survive inside white blood cells that engulf them because they are resistant to chemicals and enzymes that the WBC uses to attack

What is the definition of T-independent antigens and what are examples?

·-T-independent: antigens that stimulate B cells directly w/o help of T cells. generally provoke weaker immune response than T-dependent-ex bacterial capsules