A client's ankle is edematous after an ankle sprain. Which physiological mechanism is responsible for the swelling?
Histamine-mediated vascular permeability leading to fluid transudation.
Bradykinin cascade resulting in the accumulation of substance P.
Thromboxane A activation of chemical mediators.
Neutrophil migration secondary to chemotaxis.
The Correct Answer is A
A) Histamine-mediated vascular permeability leading to fluid transudation:
Correct. Ankle edema following an ankle sprain is often due to inflammation and increased vascular permeability. Histamine, released from mast cells and basophils during the inflammatory response, causes vasodilation and increases vascular permeability. This leads to the leakage of fluid from the blood vessels into the surrounding tissues, resulting in edema.
B) Bradykinin cascade resulting in the accumulation of substance P:
While bradykinin is involved in the inflammatory response and can contribute to pain and vasodilation, it does not directly cause fluid transudation leading to edema in the context of an ankle sprain.
C) Thromboxane A activation of chemical mediators:
Thromboxane A is involved in platelet aggregation and vasoconstriction rather than increasing vascular permeability and edema formation.
D) Neutrophil migration secondary to chemotaxis:
Neutrophil migration is part of the inflammatory response and can contribute to tissue damage and inflammation, but it is not the primary mechanism responsible for the development of edema following an ankle sprain.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. Myocardial infarction:
Myocardial infarction (MI) typically presents with severe and prolonged chest pain or discomfort that is not relieved by rest or nitroglycerin. MI is characterized by myocardial necrosis due to prolonged ischemia, often resulting from the occlusion of a coronary artery by a thrombus or plaque rupture. While chest pressure and breathlessness are symptoms commonly associated with MI, the transient nature of the symptoms described by the client, as well as their relief after rest, is more indicative of stable angina rather than MI.
B. Unstable angina:
Unstable angina is characterized by new-onset angina, increasing frequency, or worsening intensity of angina symptoms. It is considered a medical emergency as it may precede a myocardial infarction. However, unstable angina typically presents with symptoms at rest or with minimal exertion and is not usually relieved by rest or nitroglycerin. The client's symptoms, which are relieved by rest, are more consistent with stable angina.
C. Stable angina:
Stable angina is characterized by predictable chest pain or discomfort that occurs with exertion or stress and is relieved by rest or nitroglycerin. The symptoms described by the client, including chest pressure and breathlessness that improve with rest, are consistent with stable angina. Stable angina occurs due to transient myocardial ischemia caused by an imbalance between myocardial oxygen supply and demand, often related to coronary artery disease.
D. Prinzmetal angina:
Prinzmetal angina, also known as variant angina, is characterized by chest pain or discomfort that occurs at rest, often in the early morning hours, and is typically caused by coronary artery spasm rather than fixed atherosclerotic lesions. While Prinzmetal angina can present with transient symptoms similar to those described by the client, it is less common than stable angina and is often associated with transient ST-segment elevation on electrocardiogram (ECG), which is not mentioned in the scenario.
Correct Answer is A
Explanation
The atrioventricular (AV) node is an essential component of the cardiac conduction system responsible for transmitting electrical impulses from the atria to the ventricles. The inherent rate of the AV node refers to its intrinsic ability to generate electrical impulses in the absence of external influences.
Here's a breakdown of each option:
A) 40 to 60:
Correct. The inherent rate of the AV node is typically 40 to 60 beats per minute (bpm). This rate is slower than that of the sinoatrial (SA) node, which has an inherent rate of 60 to 100 bpm. The AV node acts as a backup pacemaker, ensuring that the ventricles receive electrical impulses even if the SA node fails to function properly.
B) 20 to 40:
This range is not consistent with the typical inherent rate of the AV node. A rate of 20 to 40 bpm would be unusually slow and could indicate significant conduction system abnormalities rather than the normal functioning of the AV node.
C) 60 to 80:
This range is more characteristic of the inherent rate of the SA node rather than the AV node. The SA node is the primary pacemaker of the heart, and its inherent rate is typically 60 to 100 bpm.
D) 80 to 100:
Similar to option C, this range is more consistent with the inherent rate of the SA node rather than the AV node. The SA node typically has a faster intrinsic rate compared to the AV node.
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