Smartworks Chapter 23
How does a moderate fever slow bacterial growth?
produces suboptimal temperatures for the microbe
Complement protein factor C3b is an opsonin, which means it can
promote phagocytosis
Components of the skin, GI tract, and lungs:
skin: - langerhans cells - sebum GI tract: - m cells lungs: - alveolar macrophages - cystic fibrosis transmembrane conductance regulator - mucociliary escalator
Microbial species of the microbiota may interfere with colonization of pathogens by which of the following mechanisms?
- competition for food sources - through the synthesis of antimicrobial compounds - competition for attachment receptors on host cells phagocytosis is not a mechanism for colonization interference
Michael has Acquired Immunodeficiency Syndrome (AIDS) caused by the Human Immunodeficiency Virus (HIV). The damage that the virus has done to Michael's immune system has made him susceptible to a yeast infection of his respiratory tract, called Candidiasis. Individuals with a healthy immune system do not develop this yeast infection. Michael is a(n) ___________ and the yeast that causes Candidiasis is a(n) ________________
compromised host, opportunistic pathogen
Which of the following chemical defenses are produced by host cells to destroy invaders' membranes?
defensins
The inflammatory response depends on the interaction of many inflammatory molecules and cellular proteins. Which of the following pairs of molecules or cells does not interact?
endothelial VCAM - mast cells do not interact pairs that do interact: - neutrophil integrins and endothelial ICAM - endothelial prostaglandins and nerve cells - endothelial selection and neutrophil surface carbohydrates
Type I interferons
help protect cells from viral infection
Microbes that colonize the skin need to be resistant to __________ salt and __________ pH
high, low
Organs have varied mechanisms for limiting the amount and types of colonizing microbiota. In the choices below, organs are matched with one of their microbiota-limiting mechanisms. Which organ and mechanism are mismatched?
incorrectly matched: - bladder: presence of bile salts (bile salts are actually found in the intestine) correctly matched: - eye: constant washing action with antimicrobial factors such as lysozymes - lungs: action of the mucociliary escaltor - skin: presence of dry, high salt environments - intestine: secretion of lectins that separate the microbiome from the host mucosal cells
Pyrogens indirectly cause the hypothalamus to
increase the temperature set point
Extravasation of immune cells depends on
increased permeability of endothelial cell junctions
Below are two statements about the immune system: Macrophages ingest and degrade microbes and present the microbial antigens to other immune system cells.Antibodies on the surface of virally infected host cells activate natural killer (NK) cells. These two statements are examples of the connections between which of the following?
innate and adaptive branches of immunity
Differences between innate and adaptive immunity
innate immunity: - involves physical barriers - is nonspecific - includes the alternative complement pathway - is triggered by peptidoglycan and lipopolysaccharide adaptive immunity: - involves specific antigens - involves memory cells - produces antibodies - reacts more slowly during the initial infection
Which of the following is true of the immune system?
- it is capable of responding to almost any foreign molecule - its cells differentiate between self and nonself - it includes organs, cells, and cell products it is untrue that its two branches, innate and adaptive, are isolated from each other
Which of the following statements about macrophages is true?
- macrophages differentiate only from monocytes - macrophages present microbial peptide antigens on major histocompatibility complexes - macrophages are phagocytic It is false that macrophages are involved only in innate immunity (since they are also involved in adaptive immunity)
The gut microbiome benefits the host in many ways. One benefit of the gut microbiome is that it helps to prevent infection by pathogenic microbes. To directly compete with and inhibit the growth of pathogenic microbes, members of the gut microbiome do which of the following?
- occupy attachment receptors - secrete substances that inhibit the growth of pathogens - compete for nutrients
The microbiome has both associated benefits and risks. What are some of the risks associated with the oral microbiome?
- tooth decay - bacteremia - subacute bacterial endocarditis
Order of inflammatory response:
1. macrophages engulf microbes and release cytokines 2. movement of neutrophils through the capillaries slows and the junctions between endothelial cells loosen 3. neutrophils extravasate 4. neutrophils phagocytose invading microbes
Step of phagocytosis:
1. phagocyte pseudopods clasp and engulf the microbe 2. the microbe is trapped within the phagosome 3. a lysosome fuses with the phagosome, forming a phagolysosome 4. enzymes cleave macromolecules and generate reactive oxygen species, destroying the microbe 5. the microbial debris is released from the cell
Which of the following cell types is present in gut-associated lymphoid tissue (GALT) and takes up microbes, releasing them into pockets containing macrophages?
M cells
Which of the following cells is most likely to be killed via the alternative complement pathway?
a gram-negative bacterium
Which of the following complement pathways is activated by lipopolysaccharide?
alternative complement pathway
An individual is infected with Mycobacterium tuberculosis. The bacteria infect macrophages in the lungs, where it survives and reproduces intracellularly. What is the most likely mechanism the infected macrophages will use to combat the invading bacteria?
autophagy
Which of the following activates a natural killer (NK) cell to kill a host cell?
presence of antibodies on the host cell, or absence of MHC I on the host cell
In which of the following body sites would the mere presence of microbes indicate an infection?
blood
Which of the following locations is LEAST likely to harbor commensal microbes?
blood
Some cells of the innate immune system present antigens to T cells of the adaptive immune system. Cells that can present the antigens are logically called antigen-presenting cells (APCs) and include which of the following?
cells that present antigens: - dendritic cells - macrophages cells that do not present antigens: - natural killer cells - neutrophils - eosinophils - basophils
The immune system
is a system that differentiates self from non self to neutralize harmful invaders
Which of the following is true of the normal intestinal microbiota?
it can help aid digestion and adsorption of nutrients it is false that there are up to two dozen different species present, the microbes that are present will not harm the host if they colonize a different tissue, and the normal microbiota contains only bacterial species
How does the alternative complement pathway kill the invading microbial cell?
it destroys the proton motive force required for energy production
Which of the following is not an innate chemical defense used by the host to protect itself against infection?
microbe-associated molecule patterns
Moderate fever can actually be beneficial because it
moves the temperature outside the pathogen's optimal range
Differences between neutrophils and basophils:
neutrophils: - are phagocytic - produce lattice-works of DNA that trap pathogens - are the majority of leukocytes in blood basophils: - contain IgE receptors associated with allergies - are similar to mast cells
Innate immunity is also called ____________ immunity
nonadaptive
Bradykinin plays several roles in inflammation. According to the figure, which of the following is not a function of bradykinin in inflammation?
stimulating the release of cytokines by macrophages functions of bradykinin in inflammation: - loosening the junctions between endothelial cells - causing capillary cells to release prostaglandins - triggering the release of histamine from mast cells
Which complement cascade pathway depends on the production of antibodies?
the classical pathway
Pseudomembranous enterocolitis is caused by an overgrowth of the bacteria Clostridioides difficile. This overgrowth can be caused by antibiotic therapy in which sensitive members of the microbiome are killed or inhibited by the antibiotic drug, but the resistant C. difficile is not. Because the C. difficile infection is resistant to many antibiotics, it is hard to treat. Cases of pseudomembranous enterocolitis have been cured with fecal transplants in which the gut microbiome of a donor healthy person is transferred into the patient. Fecal transplants work to cure this resistant infection because
the donor's healthy microbiome outcompetes the C. difficile and restores balance to the gut microbiome in the patient
Which of the following is true of macrophages?
they are the cells most likely to first encounter an invading pathogen
Which of the following is a physical barrier to microbial infection in innate immunity?
tightly linked epithelial cells
Which receptors on host cells participating in innate immunity recognize bacterial proteins?
toll-like receptors
Interferons are cytokines produced by host cells in response to intracellular infection. There are two types of interferons, type I and type II. Which of the following is a difference between these two types?
type I interferes with viral replication, while type II activates white blood cells
Which of the following host cell products prevents viral infections by inhibiting viral replication?
type I interferons
The five classic signs of localized inflammation are redness, warmth, pain, swelling, and altered function at the affected site. Altered function is caused when swelling interferes with the movement and function of the inflamed area. The other signs are matched with their causes below. Which sign and cause are mismatched?
warmth: increased production of pyrogens signs matched correctly with causes: - redness: increased blood flow to the site - pain: increased production of prostaglandin - swelling: increased vascular permeability
A Streptococcus pneumoniae mutant does not produce a capsule. What will be the most likely result of this mutation if the bacteria infect a host?
without the capsule, opsonization of the mutant will not be required for host macrophages to ingest the microbe, making it less pathogenic
