The number of _____ typically increases in response to bacterial infections.
Basophils
Monocytes
Erythrocytes
Eosinophils
Neutrophils
The Correct Answer is E
A. Basophils: These are the rarest leukocytes and primarily release histamine and heparin to mediate inflammation and allergic reactions. While they respond to injury, their numbers do not typically spike as a primary defense against systemic bacterial proliferation. They are more involved in localized chemical signaling.
B. Monocytes: These cells are the precursors to macrophages and are involved in chronic infections and antigen presentation. While they increase during the later stages of an infection, they are not the primary "first responders" that show a rapid, massive increase during acute bacterial invasion. They focus on cellular debris and phagocytosis.
C. Erythrocytes: These are red blood cells responsible for oxygen transport and do not have a functional role in the immune system. Their count remains relatively stable during an infection and does not increase to fight bacteria. An increase in erythrocytes is typically a response to hypoxemia rather than a pathogen.
D. Eosinophils: These granulocytes specialize in destroying large parasites, such as helminths, and modulating allergic responses. Their count typically rises in response to parasitic infestations or asthma rather than bacterial pathogens. They utilize cytotoxic granules to attack multicellular invaders.
E. neutrophils: These are the most abundant white blood cells and act as the primary defense against acute bacterial infections. A high neutrophil count, or neutrophilia, is a standard clinical indicator of an active bacterial process. They utilize phagocytosis and respiratory bursts to rapidly neutralize invading prokaryotic cells.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
A. R wave: The R wave is the prominent upward deflection of the QRS complex and represents the depolarization of the main mass of the ventricles. It marks the electrical signal for ventricular contraction, not the recovery phase. It is an electrical event related to the initiation of ventricular systole.
B. QRS wave: This complex represents the total electrical activity associated with ventricular depolarization. It consists of the Q, R, and S deflections and obscures the electrical signal of atrial repolarization. While it is a critical ECG landmark, it indicates the onset of ventricular activation rather than its recovery.
C. P wave: The P wave is the initial small deflection of the ECG cycle and represents atrial depolarization. This electrical event triggers the subsequent contraction of the atria to move blood into the ventricles. It occurs well before the ventricles are electrically activated or repolarized.
D. S wave: The S wave is the final downward deflection of the QRS complex, representing the depolarization of the base of the heart. Like the R wave, it is part of the electrical sequence that leads to ventricular contraction. It does not represent the return of the ventricular myocytes to their resting state.
E. T wave: The T wave is the deflection on the ECG that represents the electrical recovery, or repolarization, of the ventricular myocardium. This process allows the ventricular cells to return to their resting potential in preparation for the next cycle. It occurs during the middle and final stages of ventricular systole.
Correct Answer is E
Explanation
A. Breathing: Thoracic pressure changes during inspiration and expiration can influence venous return to the heart. However, these pressure fluctuations are not the direct mechanical force that operates the cardiac valves. Valve function is localized to the hemodynamics occurring within the cardiac chambers themselves.
B. Gravity: While gravity affects blood distribution in the upright position, it is not the mechanism responsible for the rapid snapping open and shut of heart valves. The heart must generate significant internal forces to overcome gravitational pull and ensure forward flow. Valves rely on active fluid dynamics rather than passive positioning.
C. valves contracting and relaxing: Heart valves are passive structures composed of endocardium and connective tissue that do not possess muscular tissue. They do not have the physiological ability to contract or relax on their own like myocardium. They move strictly in response to the movement and pressure of the blood.
D. osmotic gradients: Osmotic gradients govern the movement of water across semipermeable membranes in the capillaries. They have no mechanical role in the movement of large anatomical structures like the atrioventricular or semilunar valves. Valve operation is a macro-mechanical process driven by hydrostatic force, not molecular osmosis.
E. pressure gradients: The opening and closing of heart valves are driven by differences in fluid pressure on either side of the valve. When pressure in a proximal chamber exceeds that of a distal chamber, the valve is pushed open. Conversely, backpressure from a distal chamber forces the valve leaflets to seal shut.
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