In the normal electrocardiogram, the PR interval represents
Atrial depolarization
Ventricular depolarization
Atrial activation of the onset of ventricular activity
“electrical systole” of the ventricles
The Correct Answer is C
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.
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Naxlex Comprehensive Predictor Exams
Related Questions
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.
Correct Answer is D
Explanation
Hemoptysis is the coughing up of blood or bloody secretions from the respiratory tract. It is a sign of a serious condition and should be reported immediately to a healthcare provider. In this case, the patient's cold and cough may have led to irritation and inflammation of the respiratory tract, resulting in hemoptysis.
- Hematemesis: This is the vomiting of blood from the upper gastrointestinal tract, which usually appears bright red or dark brown in color.
- Cyanosis: This is a bluish discoloration of the skin and mucous membranes caused by the presence of deoxygenated hemoglobin in the blood.
- Rhinitis: This is the inflammation of the nasal mucosa, often causing a runny nose, nasal congestion, and sneezing.
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