Which factor is responsible for the hypertrophy of the myocardium associated with hypertension
Acetylcholine
Adducin
Angiotensin II
Insulin resistance
The Correct Answer is C
Hypertension, or high blood pressure, is a major risk factor for the development of left ventricular hypertrophy (LVH), which is characterized by thickening of the myocardium (heart muscle). LVH occurs in response to increased afterload (the resistance the heart has to pump against), which is a common feature of hypertension.
Angiotensin II, a hormone that is activated in response to hypertension, is a major mediator of LVH in this setting. Angiotensin II causes vasoconstriction (narrowing of blood vessels) and promotes the retention of salt and water, which increases blood volume and pressure. Additionally, angiotensin II stimulates the proliferation of cardiac myocytes (heart muscle cells) and the synthesis of extracellular matrix proteins, leading to hypertrophy and fibrosis of the myocardium.
Other factors that may contribute to LVH in hypertension include increased sympathetic nervous system activity, oxidative stress, and inflammation. However, angiotensin II is considered a key mediator of this process, and drugs that block the renin-angiotensin-aldosterone system (RAAS), such as angiotensinconverting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), are often used to treat hypertension and reduce the risk of LVH and other cardiovascular complications.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
In the normal electrocardiogram, the PR interval represents
The PR interval represents the time from the onset of atrial activation to the onset of ventricular activity. During this time, the electrical impulse travels through the atria, the atrioventricular (AV) node, and the bundle of His before entering the ventricles and initiating ventricular depolarization. Option A is incorrect because the atrial depolarization is represented by the P wave. Option B is incorrect because the ventricular depolarization is represented by the QRS complex. Option D is incorrect because there is no such term as “electrical systole” of the ventricles in ECG interpretation.
Correct Answer is B
Explanation
Croup is a common respiratory illness in young children, characterized by inflammation of the upper airways (including the larynx and trachea) that leads to a characteristic barking cough and difficulty breathing. Croup is most commonly caused by viral infections, particularly parainfluenza virus, although other viruses such as respiratory syncytial virus (RSV) and influenza virus can also be responsible. 
Bacterial croup is rare and usually occurs in children who have an underlying condition that makes them more susceptible to bacterial infections, such as immunodeficiency or a history of recurrent respiratory infections. Fungal croup is also rare and usually occurs in children with a weakened immune system or a history of exposure to contaminated soil or other environmental sources of fungi.
Autoimmune croup is not a recognized medical condition. While some autoimmune disorders can affect the respiratory system (such as systemic lupus erythematosus), they do not typically cause croup-like symptoms.
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