Which sequence correctly represents phagocytosis?
Chemotaxis, engulfment, digestion, exocytosis.
Digestion, chemotaxis, engulfment, exocytosis.
Engulfment, digestion, chemotaxis, exocytosis.
Engulfment, chemotaxis, digestion, exocytosis.
The Correct Answer is A
Choice A rationale
Phagocytosis begins with chemotaxis, where phagocytes are chemically attracted to the site of inflammation or infection by signaling molecules. Once the phagocyte reaches the pathogen, engulfment occurs as the cell membrane surrounds the target to form a phagosome. Digestion follows as lysosomal enzymes break down the ingested material within a phagolysosome. Finally, exocytosis is the process of discharging the residual waste products from the cell. This chronological sequence ensures efficient clearance of pathogens.
Choice B rationale
This sequence is scientifically incorrect because digestion cannot occur before the pathogen has been identified or internalized by the immune cell. Digestion is a late-stage process requiring the fusion of a phagosome with a lysosome, which only happens after chemotaxis and engulfment have been successfully completed. Placing digestion at the start of the process ignores the necessity of cellular movement and the physical internalization of the foreign body required for enzyme exposure and degradation.
Choice C rationale
Starting the sequence with engulfment ignores the critical first step of chemotaxis. Phagocytic cells such as neutrophils and macrophages do not randomly encounter pathogens in the tissues; they must be actively recruited and directed toward the higher concentration of inflammatory mediators or bacterial toxins. Without chemotaxis, the phagocyte would not arrive at the specific location necessary to perform engulfment. Therefore, this sequence fails to account for the essential recruitment phase of the innate immune response.
Choice D rationale
While this sequence includes the correct components, the order is flawed because engulfment cannot precede chemotaxis. Chemotaxis provides the directional guidance for the immune cell to find the target. If engulfment were to occur first, it would imply the cell is already in contact with the pathogen without a recruitment phase. The standard biological progression requires the cell to first sense the chemical gradient, move toward the source, and only then engage in the physical engulfment.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice B rationale
An increased heart rate, or tachycardia, in the context of thyroid storm can escalate to life-threatening arrhythmias or high-output heart failure. Thyroid storm is a hypermetabolic state where excessive thyroid hormones sensitize the heart to catecholamines. Rapid intervention is required to prevent cardiovascular collapse. A normal heart rate is 60 to 100 beats per minute, but in thyroid storm, it often exceeds 140 beats per minute, necessitating immediate administration of beta-blockers and antithyroid medications.
Choice A rationale
Heat intolerance is a common symptom of hyperthyroidism and thyroid storm due to the greatly increased basal metabolic rate and thermogenesis. While uncomfortable for the patient, it is an expected finding and generally does not pose an immediate threat to life compared to cardiovascular instability. Nursing interventions include providing a cool environment and cooling blankets, but this does not take priority over managing the profound tachycardia or potential for cardiac arrest associated with this endocrine crisis.
Choice C rationale
Weight loss is a chronic manifestation of hyperthyroidism resulting from a prolonged hypermetabolic state and increased calorie utilization. In an acute thyroid storm, weight loss is a historical finding rather than an immediate physiological threat. While it confirms the underlying diagnosis, it does not require emergency intervention in the same way that hemodynamic instability does. The focus during an acute storm is on stabilizing the patients vital signs and blocking the systemic effects of thyroid hormone.
Choice D rationale
Increased anxiety and irritability are neurological manifestations of excess thyroid hormone affecting the central nervous system. While the patient may experience significant psychological distress or even psychosis during a thyroid storm, these symptoms are typically secondary to the physiological crisis. Although safety measures and sedation may be necessary, the most critical risk to the patients survival remains the extreme sympathetic overactivity and its impact on the heart rate and core body temperature.
Correct Answer is A
Explanation
Choice A rationale
Albumin is the primary protein responsible for maintaining plasma oncotic pressure, also known as colloid osmotic pressure. Normal serum albumin ranges from 3.5 to 5.0 g/dL. This pressure acts like a sponge, pulling water from the interstitial spaces back into the vascular compartment. When albumin levels are low, this pulling force decreases significantly. Consequently, the fluid that normally moves out of the capillaries cannot be effectively reabsorbed, leading to accumulation in the tissues.
Choice B rationale
Decreased capillary permeability would actually prevent fluid from leaving the vascular space and entering the tissues. In conditions involving generalized edema due to low albumin, the permeability of the capillary walls themselves is often unchanged. The issue is not the size of the pores in the vessel walls, but rather the loss of the inward osmotic gradient that keeps fluid inside. Therefore, permeability changes do not explain the edema seen in hypoalbuminemia or nephrotic syndrome.
Choice C rationale
Increased osmotic pressure in the interstitial space would happen if there were an accumulation of solutes or proteins outside the blood vessels. While this would cause edema, it is not the mechanism triggered by low serum albumin. In hypoalbuminemia, the problem is a lack of pressure within the vessel, not an excess of pressure outside. The shift is driven by the loss of the intravascular oncotic gradient rather than an active increase in interstitial osmotic forces.
Choice D rationale
Increased hydrostatic pressure is the force exerted by blood against the vessel wall, typically seen in heart failure or fluid overload. While high hydrostatic pressure does push fluid into the tissues, it is a different mechanism from oncotic pressure loss. In a client with low albumin, the hydrostatic pressure might be normal, but because the opposing oncotic pressure is so weak, the net fluid movement is still directed outward into the interstitial space, causing edema.
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