chapter 16 quiz

Some mechanisms are very straightforward and involve the production of leukocidin

, an exotoxin that kills white blood cells.

Phagocytes must bind to the surface of microbes to initiate the process of engulfing the microbe

This binding is facilitated by the specific attachment of Toll-like receptors (TLRs) on the phagocyte with pathogen-associated molecular patterns (PAMPs) on the microbe surface

Examples of PAMPs

This is the case with M protein, a component on the surface of Streptococcus pyogenes include peptidoglycan, lipopolysaccharide, flagellin, and bacterial DNA or viral DNA and viral RNA. Various microbial substances can interfere with this attachment process and thus interfere with phagocytosis

Alternative pathway

This pathway involves factors B, D, and F binding to pathogen.

Lectin pathway

This pathway involves secretion of waste products by phagocytes.This pathway involves phagocytes engulfing pathogens.

Classical pathway

This pathway requires antibody-antigen complex.This pathway requires C1 to become activated.This pathway requires previous activation of the adaptive immune response.

What is the function of inflammation

To destroy the agent causing injury, to limit the effects of the agent on the rest of the body, and to repair the damaged tissue

If a new bacterial pathogen entered a human body through an accidental needle stick, the first cell that would try to kill the pathogen would likely be

a phagocyte.

Enhances phagocytosis

antibody molecules attaching to microbe surfacecomplement peptides deposited on microbe surface

The process by which a phagocyte moves toward a chemical signal at the site of an infection is called

chemotaxis

Pus is comprised of

dead phagocytes.

The digestive enzymes provided by the lysosome

include lysozymes, lipases, proteases, ribonucleases, and deoxyribonucleases. A process referred to as the oxidative burst generates superoxide radicals (O2−⋅), hydrogen peroxide (H2O2), nitric oxide (NO), singlet oxygen (1O2−) and hydroxyl radical (OH⋅)

Mucous membranes are a part of

innate defense.

Select the cell types that are actively phagocytic.

macrophage neutrophil eosinophil dendritic cell

Select each of the items that would be likely to interfere with the killing of microbes once phagocytes have ingested them. Assume that chemotaxis, attachment, and ingestion occurred normally.

myeloperoxidase deficiency defective oxidative burst defective microtubule function

The pumping of hydrogen ions (H+) into the phagosome

rapidly acidifies this vesicle, providing the optimal environment to activate the hydrolytic enzymes delivered by lysosomes

Chemotaxis

refers to the movement of a cell in response to a chemical stimulu is brought about by the binding of various chemoattractant substances (microbial components, complement components, cytokines) to receptors on the surface of phagocytes. This triggers cell movement toward higher concentrations of the attractant. The interaction of actin microfilaments and myosin (cytoskeletal elements) within the phagocyte makes this movement possible.

Select each of the items from the list that would enable a microbe to evade phagocytosis or avoid phagocytic killing.

A capsule surrounds the microbe. Microbe produces leukocidin. Microbe escapes from phagosome prior to fusion with lysosome. Microbe prevents fusion of phagosome with lysosome to form phagolysosome.

With respect to the membrane attack complex (MAC), which is most likely to occur once all of the C9 proteins insert into the bacterial plasma membrane?

A hole will form in the bacterium, allowing water to rush into the cell and causing lysis.

Life within a phagosome

A phagosome is the vesicle that is formed as a microbe is engulfed during phagocytosis. The phagosome contains the microbe as well as some of the extracellular fluid. As soon as this vesicle pinches off, hydrogen ions are pumped into the vesicle, lowering the pH. How will this pH change affect most microbes? What does this acidification process accomplish

helper T cells.

According to the animation, B cells interact directly with

Which of the complement pathways employs properdin?

Alternative pathway

The lysosome, the "destroyer"

Although life within a phagosome alone may not be so bad, the going gets tough when the lysosome fuses with the phagosome, dumping its assortment of hydrolytic enzymes into the newly formed phagolysosome. The oxidative burst is also triggered at this point, generating a number of different toxic oxygen products. What will happen if a microbe can prevent the fusion with the lysosome, or if the microbe can escape from the phagosome prior to the fusion?

Antibodies from cellular immune responses are used in

the classical pathway.

A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component?

Antibodies

which of the following is cleaved by C1?

C2 and C4

which of the following is responsible for cleaving C3?

C2aC4b

Inflammation stimulation

C3a fragments act as chemotactic agents.C5a fragments recruit immune cells to the site of infection.Neutrophils are attracted to the area and arrive via diapedesis.

In the classical pathway, which of the following directly activates cellular responses?

C3a, C5a, and C5bC6C7

Which complement protein is used as an opsonin?

C3b

which of the complement proteins can directly bind to the surface of a bacterial cell?

C3b

Which of the following can release histamines?

Cells from damaged tissues and the complement pathway

How do complement components affect phagocytosis?

Certain complement peptides produced when the complement cascade is activated will attach to microbial cells, opsonizing them. Phagocytic cells have particular receptors on their surfaces for these complement peptides. Opsonization enhances the adherence of phagocytes to microbes. What effect will this have on phagocytosis?

What complement result involves the use of phagocytes?

Chemotaxis and opsonization

Phagocytosis is defined as

the ingestion of solid material by a eukaryotic cell.

Emigration is

the migration of phagocytes through blood vessels to the site of tissue damage.

Both the innate and adaptive defenses of the immune system work to prevent

the penetration and colonization by pathogens, and the diseases they cause.

Which microorganism requires the low pH inside a phagolysosome in order to reproduce?

Coxiella burnetii

If a person could not form C2, which result of complement would be affected?

Cytolysis, chemotaxis, inflammation, and opsonization

Which cells directly attack abnormal cells in the body?

Cytotoxic T cells

Which of the following phagocytic processes occurs last in the sequence?

Exocytosis

How does cytolysis occur via the complement pathway?

Formation of the MAC in invading cells, killing them

What does the plasma membrane of a phagocyte attach to on a microorganism?

Glycoproteins

Does lipopolysaccharide play a role in phagocytosis?

Gram-negative bacterial cells have lipopolysaccharide (LPS) on their cell surfaces. This cell wall component is referred to as a pathogen-associated molecular pattern (PAMP), and it is recognized by Toll-like receptors on phagocyte surfaces. How might this recognition affect phagocytosis?

Why is vasodilation important to tissue repair?

It allows for an increased delivery of oxygen, nutrients, and phagocytes to the site of damage.

How does M protein affect phagocytosis?

M protein is found on the surface of Streptococcus pyogenes cells. This protein interferes with the interaction of Toll-like receptors on the phagocyte surface with PAMPs on the microbe.

Interferes with phagocytosis

M protein of Streptococcus pyogenesmicrobial capsulesdeposition of host-derived fibrin on microbe surface

Direct cell lysis

MAC introduces holes to the bacterial cell membrane.C9 is polymerized into a circular-shaped complex on the pathogen surface.Multiple transmembrane proteins are recruited to the pathogen.

Opsonization

Macrophages and neutrophils are attracted to C3 protein molecules bound to the pathogens, making them easier to phagocytize.C3b fragments bind to the surface of pathogens.

In the Case of Classical Activation, Which Outcome Is Likely to Occur?

Membrane attack complex will form. Inflammation will be stimulated. Pathogens will become opsonized.

How does a microbial capsule affect phagocytosis?

Microbial capsules tend to mask pathogen-associated molecular patterns (PAMPs) and interfere with attachment of phagocytes to their microbial targets. What effect would this have on phagocytosis?

Does peptidoglycan play a role in phagocytosis?

Nearly all bacterial cells have peptidoglycan. This cell wall component is referred to as a pathogen-associated molecular pattern (PAMP), and it is recognized by Toll-like receptors on phagocyte surfaces. How might this recognition affect phagocytosis?

If a person lacked the ability to form C5, what direct result of complement could still occur?

Opsonization

antibodies directly interact with which innate defenses?

Phagocytosis and the complement system

What cellular macromolecules make up the complement pathway?

Proteins

Part complete How is phagocytosis in the immune system different from protozoan phagocytosis?

Protozoan phagocytosis is used for feeding; phagocytosis by immune cells is used to fight infection.

How do antibodies affect phagocytosis?

Some antibodies attach to their target microbial cells, opsonizing them. Phagocytes have receptors for the Fc region of antibody molecules, and this receptor-antibody interaction promotes the attachment of the phagocyte to the microbe. What effect will this have on phagocytosis?

. How do some host proteins interfere with attachment of phagocytes?

Some microbes cause host proteins to be deposited on their surface. This effectively masks the PAMPs and confuses the phagocyte into thinking the microbe is "self" and not worthy of attention.

Which of the following microorganisms use M protein to avoid destruction of a phagocyte?

Streptococcus pyogenes

myeloperoxidase enzyme in the phagolysosome

will catalyze a reaction between H2O2 and chloride (Cl−) ions to produce highly toxic hypochlorous acid (HOCl). The combined effect of the hydrolytic enzymes, toxic oxygen products, and hypochlorous acid bring about the destruction of the ingested microbe.

Which of the following defense systems would be involved in eliminating virally-infected cells?

T lymphocytes

Where are the complement proteins found in the body

The blood serum

What is a phagolysosome?

The structure that results from the fusion of a phagosome and a lysosome.

How is Streptococcus pneumoniae able to avoid destruction by a phagocyte?

Their capsules make them "slippery" to phagocytes.

Which of the following are functions of lectins?

They act as opsonins for phagocytosis, they attach to carbohydrates on some bacterial and viral surfaces, and they activate C2 and C4.

What direct effect do histamines and leukotrienes have on capillaries?

They allow capillary walls to open and become leaky.

First line defenses have what aspect in common with each other?

They are physical barriers against invading pathogens.

What is the role of opsonins?

They create "handles" that make it easier for the pseudopods of phagocytes to attach to the microbe invader.