Micro Inquiz Chapter 15

Which of the following accurately describe the relationship between complement and Gram-positive bacteria?

Complement factors attract phagocytes, which target Gram-positive cells. Antibody coated Gram-positive bacteria can activate complement. Gram-positive bacteria are resistant to complement killing.

Some 'semi-specific' innate immune defenses exist and are capable of distinguishing non-self structures and molecules in a much less specific way than adaptive immune defenses. Some examples of this are virally or bacterially associated patterns.

Conserved, repeating non-self structures on microbes, such as peptidoglycan in bacterial cell walls, are called pathogen-associated molecular patterns. These structures can be recognized by receptors on host cell surfaces called Toll-like receptors. Once non-self patterns are recognized by these receptors, chemicals are released that can activate additional components of the immune system. pathogen-associated molecular patterns Toll-like receptors

What is the fate of neutrophils that have entered tissue to control infection?

They undergo apoptosis. They are phagocytized by macrophages.

Innate immune mechanisms alone are enough to kill many pathogens, but they are more effective when combined with adaptive responses.

True

Regardless of the activation pathway used, the complement system always proceeds identically from the splitting of C3 to the formation of the membrane attack complex.

True pages 479-480

Mycobacterium tuberculosis can result in the formation of a granuloma.

True page 469

Lymphoid stem cells may differentiate into which of the following cell types?

lymphocytes natural killer cells

Staphylococcus aureus have entered Kim's bloodstream through a small cut on her hand. These organisms are the same strain Kim was exposed to when she scraped her knee a few months ago. When the organisms enter her bloodstream, antibodies to a cell surface protein are able to bind to the bacterial cells. The Fc regions of the antibodies are now exposed to phagocytes that can bind them. This is best described as ___________ .

opsonization

Complement proteins in serum are so named because they enhance the effect of antibodies on bacteria. Which of the following are ways in which complement assists in protecting against bacterial infection?

opsonization membrane attack complex pages 479-481

Toll-like receptors are embedded in cellular membranes. However, a similar receptor system exists to allow recognition of PAMPs within cells. What are these intracytoplasmic receptors known as?

NOD-like receptors

Which is true of antibody-dependent cell-mediated cytotoxicity (ADCC)?

Natural Killer cells destroy the target. Host cells are opsonized by antibodies.

sepsis is a life threatening condition that can be brought on by an over-reactive host immune response to infection. Place the steps leading to septic shock in order following initial infection.

PAMPs are recognized by TLRs. Pro-inflammatory cytokines are released. Endothelial layer becomes damaged. Clotting factors are exposed. Initial clot formation depletes platelets leading to bleeding. 476-477

Which feature in this figure allows bacteria to evade phagocytosis?

Page 470 click the first picture to the left side

Drag the correct words to complete the sentence below.

During the course of an infection with the Gram-negative bacterium Escherichia coli O157:H7, bacterial cells may be recognized by pathogen-associated molecular patterns (PAMPs), which bind to a portion of LPS shared by all Gram-negative bacteria, while antibodies bind to the O157 antigen unique to this serotype. Though both may lead to destruction of the cell, the first is an example of innate immunity, while the second is an example of adaptive immunity. Innate immunity Adaptive immunity

A patient's white blood cell count with differential shows elevated neutrophils and band cells with 30% lymphocytes as a portion of the total 25,000/mm3 WBC count. What can you tell from this result?

Elevated total WBC count is indicative of acute bacterial infection. Elevated neutrophils indicate bacterial infection.

Bacteria cannot survive inside a granuloma, but they may still form around tissue in which damage from an infection has already occurred.

False

Chronic inflammation is a necessary and useful innate immune defense for preventing bacterial illness.

False

MHC molecules are antigens present on foreign cells that allow innate targeting of the cells by mechanisms like NK cells.

False

Inflammation requires many individual components of the immune system to act in concert in order to allow neutrophils to phagocytize microbes at the site of infection.

Following phagocytosis of a pathogen, macrophages release vasoactive factors as well as cytokines such as TNF-α and IL-1. On the cells lining capillaries, these cytokines stimulate the production of selectins that can bind ICAM-1 to the surfaces of neutrophils. In order to migrate through the endothelial cell layer, tight junctions must be loosened. This occurs following the release of bradykinin, a small polypeptide that causes further degranulation of mast cells and the release of histamine. Neutrophils in tissue are guided toward microbes by a special subset of cytokines, like IL-8, known as chemokines.

This brain region acts as the body's thermostat, regulating temperature via involuntary vasodilation and vasoconstriction.

Hypothalamus

Which is true of interferon?

Interferon, which is effective against measles, is also likely effective against chickenpox.

When foreign material enters the body, some white blood cell types will attempt to neutralize the threat and communicate with members of the adaptive immune response.

Macrophages and dendritic cells (both of which are derived from monocytes) are antigen-presenting cells (APCs) that display foreign material to T cells in order to initiate an adaptive immune response. Macrophages are more likely to phagocytize whole cells by the extension of pseudopods, followed by formation of a phagosome. Ingested microbes may then be destroyed by fusion of an enzyme-filled lysosome.

Why is fever potentially advantageous?

Many pathogens grow slowly above 37°C.

Sort the following terms according to their source: pathogen or host.

Pathogen Associated PAMP LPS peptidoglycan Host Associated antibody interferon NOD-like receptor TLR pages 470-474

Place the steps of acute inflammation in the order they naturally occur.

Pathogenic Staphylococcus aureus enters tissue through a cut. Macrophages phagocytize bacteria upon contact and release cytokines. Production of selectins on capillary endothelial cells is stimulated. Integrin-producing neutrophils are slowed; extravasation occurs. Neutrophils assist macrophages in phagocytizing infecting microbes. page 468

Which of the following are components of gut-associated lymphoid tissue?

Peyer's patches M cells

what mechanism prevents phagocytes from engulfing and destroying our own cells?

Phagocyte glycoproteins bind CD47. page 469

Programmed cell death, or _____________, can be induced in phagocytes by some bacteria as a mechanism of survival following phagocytosis. The death of the phagocyte allows the bacteria to escape before being destroyed.

Phagocytosis

External __________ are substances found outside the body, such as certain bacterial toxins, that cause fever.

Pyrogens page 478

Complement can be activated by multiple pathways, though the functions of many complement proteins are conserved following activation.

The alternative complement activation pathway is initiated by spontaneous cleavage of C3. In the classical and lectin pathways, C4 and C2 must initially be cleaved in order to form the C3 convertase. Once C3 has split, the component C3b acts to split C5. C3a and C5a act as chemoattractant molecules, drawing neutrophils. C3b may also act as an opsonin for phagocytes. Alternative C3 C2 C5 C5a C3b these are found in pages 479-480

Which of the situations given represent innate rather than adaptive immune responses?

Within a few hours of entry into a cut, a bacterium is killed by cytoplasmic leakage associated with complement. Phagocytized Staphylococcus is destroyed by the oxidative burst. A pathogenic bacterium deposited on the skin fails to replicate quickly because of sebum's acidic pH.

Adaptive immune mechanisms can identify and attack bacterial, viral, fungal, chemical and other foreign antigens. How many of these distinct structures can be individually recognized and targeted by a normal human immune system?

billions

This complement activation pathway relies on direct cooperation with the adaptive immune system.

classical

These antimicrobial compounds, which are active against cytoplasmic membranes, are small cationic peptides that function as an innate defense against microbial infections.

defensins

Pathogen- or microbe-associated molecular patterns would be likely to include which of the following?

double stranded RNA β-glucan or chitin lipoteichoic acid pages 464-474

The first step in the process of inflammation, ___________, describes the movement of neutrophils out of blood vessels and into tissues, allowing them access to the site of infection.

extravasation

What are the cardinal signs of inflammation?

heat edema redness pain altered function

Match the polymorphonuclear leukocyte (PMN) type to the most appropriate function or description.

phagocytize circulating bacterial pathogens Correct label: neutrophil associated with IgE-mediated allergic responses Correct label: basophil release toxins onto the surface of pathogens too large to be phagocytized Correct label: eosinophil Correct label: basophil

Lysozyme, an enzyme secreted by the body into mucous membranes, can kill microbes by cleaving peptidoglycan.

ru

Which of the following is a chemical produced by the body as part of its innate defense against microbial infection?

stomach acid superoxide radicals sebum

Bacteria may survive following phagocytosis by different mechanisms. Which of the following is not a means for bacteria to survive phagocytosis?

√Correct choicesecreting cytokines that attract other bacteria, clogging the phagosome