_________ are secreted by cells infected with viruses, alerting neighboring cells and protecting them from becoming infected.
Interferons
Granzymes
Complement system globulins
Perforins
Pyrogens
The Correct Answer is A
A. Interferons: Interferons are signaling proteins produced by virus-infected cells that warn neighboring cells of infection. They stimulate the production of antiviral proteins in surrounding cells, limiting viral replication and spread, and enhancing the innate immune response.
B. Granzymes: Granzymes are proteolytic enzymes secreted by NK cells and cytotoxic T cells to induce apoptosis in infected or cancerous cells. They act directly on target cells rather than alerting neighboring cells.
C. Complement system globulins: Complement proteins help lyse pathogens and promote opsonization, but they do not act as signaling molecules to warn uninfected cells of viral threats. Their action is primarily destructive, not protective for nearby healthy cells.
D. Perforins: Perforins form pores in target cell membranes to allow granzymes entry. They are involved in direct cytotoxicity and do not provide antiviral signaling to surrounding cells.
E. Pyrogens: Pyrogens induce fever by acting on the hypothalamus and are part of systemic inflammatory responses, but they do not protect neighboring cells from viral infection directly.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The image shows a single cycle of an electrocardiogram (ECG or EKG), which represents the electrical activity of the heart.
A (P wave):Represents atrial depolarization, which triggers the contraction of the atria.
B, C, D (QRS complex):Represents ventricular depolarization, which triggers the main contraction of the ventricles.
E (T wave):Represents ventricular repolarization, which signifies the electrical recovery and relaxation of the ventricles.
Correct Answer is A
Explanation
A. Granzymes:Granzymes are proteolytic enzymes released by NK cells into target cells after perforin creates entry pores. They trigger apoptosis by activating caspases and degrading intracellular components, allowing NK cells to eliminate virus-infected or cancerous cells efficiently.
B. Selectins:Selectins are adhesion molecules that help leukocytes migrate during inflammation. They are not enzymes and are not secreted by NK cells, as their role involves cell-to-cell binding rather than inducing apoptosis.
C. Cytokines:Cytokines are signaling molecules used for communication within the immune system. Although NK cells secrete cytokines like IFN-γ, cytokines are not proteolytic enzymes and do not directly induce programmed cell death.
D. Interferons:Interferons are antiviral signaling proteins that enhance immune defense, but they are not proteolytic and do not mediate direct killing. NK cells may secrete interferons, yet these are regulatory rather than destructive molecules.
E. Perforins:Perforins create pores in the target cell membrane, enabling granzymes to enter. While essential to NK-cell function, perforins themselves are not proteolytic enzymes, but rather pore-forming proteins.
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