In an ECG pattern, the P wave is caused by:
Repolarization of atrial muscle fibers.
Depolarization of atrial muscle fibers.
Depolarization of ventricular muscle fibers.
Repolarization of ventricular muscle fibers.
The Correct Answer is B
This means that the electrical activity that causes the atria to contract starts from the sinoatrial node and spreads across the atria.
The P wave on the ECG reflects this atrial depolarization.
Choice A is wrong because repolarization of atrial muscle fibers is not visible on the ECG, as it occurs during the QRS complex when the ventricular depolarization masks it.
Choice C is wrong because the depolarization of ventricular muscle fibers is represented by the QRS complex on the ECG, not the P wave.
Choice D is wrong because the repolarization of ventricular muscle fibers is represented by the T wave on the ECG, not the P wave.
Normal ranges for the P wave are:
Duration: less than 0.12 seconds (less than 3 small squares)
Amplitude: less than 2.5 mm (0.25 mV) in the limb leads, less than 1.5 mm (0.15 mV) in the precordial leads
Axis: between 0° and +75°12
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Kidneys are not part of the lymphatic system.
The lymphatic system is a network of vessels and organs that drain excess fluid from the tissues, transport fats and immune cells, and protect the body from infections.
Kidneys are part of the urinary system, which filters blood, regulates fluid and electrolyte balance, and produces urine.
Choice A is wrong because kidneys do not have a direct connection to the lymphatic system.
Although kidneys have lymphatic vessels in their cortex, they do not originate from the lymphatic system.
Kidneys receive blood from the renal arteries and return it to the renal veins.
The lymphatic vessels in the kidney cortex drain interstitial fluid and immune cells from the kidney tissue to the regional lymph nodes.
Some additional sentences are:
Choice B is right because kidneys are part of the urinary system, not the lymphatic system.
The urinary system and the lymphatic system have different functions and structures in the body.
Normal ranges for kidney function tests include blood urea nitrogen (BUN) of 7 to 20 mg/dL, serum creatinine of 0.6 to 1.2 mg/dL, and glomerular filtration rate (GFR) of more than 90 mL/min/1.73 m.
Normal ranges for lymphatic system tests include white blood cell (WBC) count of 4,000 to 11,000 cells per microliter, lymphocyte count of 1,000 to 4,800 cells per microliter, and immunoglobulin levels of IgG (700 to 1,600 mg/dL), IgA (70 to 400 mg/dL), IgM (40 to 230
mg/dL), IgE (0 to 100 IU/mL), and IgD (0.5 to 5 mg/dL).
Correct Answer is D
Explanation
It is measured as part of a blood test and depends on the number and size of red blood cells. It is normally 40.7–50.3% for males and 36.1–44.3% for females.
Red blood cells contain hemoglobin, which transports oxygen and nutrients to the cells and tissues of the body.
Choice A is wrong because the color of plasma is not hematocrit.
Plasma is the liquid part of blood that carries blood cells and other substances.
Choice B is wrong because hematocrit is not a disease.
It is a test that can indicate conditions such as anemia or polycythemia.
Choice C is wrong because hematocrit is not a clotting factor.
Clotting factors are proteins that help the blood to clot and prevent bleeding.
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