1.Lymphoid organs limit the spread of disease by filtering and trapping microsco
ID: 3482182 • Letter: 1
Question
1.Lymphoid organs limit the spread of disease by filtering and trapping microscopic pathogens, preventing them from traveling elsewhere in the body. Which of the following statements correctly links a functional or structural feature with the appropriate lymphoid organ?
A) The outer cortex of the thymus consists of lymphoid follicles separated by inward extensions of the capsule called trabeculae.
B) Red pulp, found in the spleen, contains macrophages that destroy old erythrocytes.
C) White pulp in the lymph nodes contains macrophages and leukocytes that filter pathogens from lymph.
D) The lymph nodes secrete hormones that produce functional T cells, which protect the body from pathogens.
2.Current medical evidence suggests that influenza virus is released in droplets created by infected individuals and can spread up to 6 feet away by sneezing, coughing, or even talking. Airborne droplets can find their way into mouths and noses or be inhaled into the lungs of nearby individuals. People may also be exposed to influenza by touching objects that have live influenza virus on them and then transferring the virus to their own mouth or nose.
The influenza virus must bypass several lines of defense to successfully invade a human host. Which of the following examples of immune defenses is linked with the correct type of immunity?
A) B cells are components of cell-mediated immunity, which is an example of adaptive or specific immunity.
B) Antibodies are proteins associated with B cells, which are components of adaptive or specific immunity.
C) Complement proteins are a component of antibody-mediated immunity, which is an example of adaptive or specific immunity.
D) T cells are the main component of antibody-mediated immunity, which is an example of innate or non-specific immunity.
3.Patients suspected of contracting the Spanish flu reported high fevers, with temperatures between 102 and 104 degrees Fahrenheit. Fever was one of the most consistent initial signs recorded by physicians in the pandemic of 1918. Patients also suffered from sore throat, fatigue, headaches, body aches, coughing, and often nosebleeds. In addition, some individuals also experienced vomiting and diarrhea. Many patients recovered, only to relapse with the return of elevated temperatures and severe respiratory distress. Postmortem examinations of patients who died of flu-related complications revealed that many suffered massive pulmonary hemorrhage, swollen lungs, and swollen spleens.
Influenza virus particles that make their way into the human bloodstream can trigger the complement system. Which of the following is not a mechanism the complement system employs to defend against blood-borne pathogens?
A) Activated complement proteins can increase cell lysis by forming a membrane attack complex.
B) Activated complement proteins secrete cytokines that enhance the immune response.
C) Activated complement proteins enhance phagocytosis through a process known as opsonization.
D) Activated complement proteins enhance the inflammatory response.
4.Influenza viruses target epithelial cells that line the respiratory tract, triggering an antiviral immune response once the host detects the virus. The innate immune system is the first line of defense against influenza infections. This non-specific response to viral exposure is composed of physical barriers that lack the ability to form any memory against the virus.
The second line of defense is the adaptive immune response, which is triggered when the physical barriers of the innate immune system have failed. Adaptive immunity is a highly specific response that takes some time to develop upon the first encounter with the influenza virus. However, the memory that develops after that initial response produces a much quicker and stronger response if the same influenza virus is encountered again.
Suppose that you are on a research team tasked with developing a vaccine that could prevent another Spanish flu pandemic. Why might the activation of T cells be considered an important target for investigation by your research team?
A) A vaccine that stimulated the production of memory T cells, which do not require a co-stimulator, would likely enhance the immune response to influenza virus antigens.
B) A vaccine that stimulated increased antibody production by memory T cells in the absence of a co-stimulator would greatly enhance the immune response to influenza antigens.
C) A vaccine that prevented T receptors from binding to MHC-viral antigen complexes would likely enhance the immune response.
D) A vaccine that produced memory T cells that require a co-stimulator would likely make the immune response to influenza virus antigens considerably more rapid.
5.Even today influenza continues to challenge the medical community. Many people are more afraid of influenza vaccines than they are of the flu virus itself. Regardless, influenza outbreaks and the likelihood of a major pandemic still exist. An outbreak of so-called "killer flu" at Fort Dix, New Jersey in 1976 revealed fears of another Spanish flu pandemic. Experts later identified the virus as the less deadly swine flu. Nevertheless, the swine flu outbreak led to a nationwide vaccination effort to prevent a pandemic, and the outbreak was limited to Fort Dix.
An influenza outbreak that occurred in the early spring of 2009 generated a significant scare. The Centers for Disease Control and Prevention (CDC), concerned that the viral outbreak would become a major pandemic, developed an emergency vaccine within weeks of the first reported case. The CDC estimated that the flu vaccine, given to over 80 million Americans, saved countless lives. Despite this vaccination effort, the deaths of between 8,000 and 18,300 individuals were attributed to the outbreak.
Without mechanisms for a rapid response, including emergency vaccine development, an outbreak of a deadlier virus could claim many more lives. So how do flu vaccines prevent influenza infection, and more importantly, the spread of viral infection among individuals?
Predicting which influenza viruses will predominate in a particular upcoming "flu season" is a daunting task for the healthcare community. An outbreak of a flu virus not protected against by that season's vaccine undermines vaccination efforts, which puts more individuals at risk in following flu seasons.
The actions of antibodies are based on their ability to bind antigens, which leads to multiple effects on pathogens such as the influenza virus. Which class of antibodies would most likely be the first secreted in response to influenza antigen in the bloodstream?
A) IgD.
B) IgM.
C)IgE.
D)IgA.
Explanation / Answer
Answer: 1) B. Red pulp, found in the spleen, contains macrophages that destroy old erythrocytes.
2) B. Antibodies are proteins associated with B cells, which are components of adaptive or specific immunity.
3) B. Activated complement proteins secrete cytokines that enhance the immune response.
4) A. A vaccine that stimulated the production of memory T cells, which do not require a co-stimulator, would likely enhance the immune response to influenza virus antigens.
5) B. IgM
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