Nursing Elites

1. Which part of the heart is responsible for generating the QRS complex on an ECG?

• A. Sinoatrial node (SA node)
• B. Atrioventricular node (AV node)
• C. Bundle of His
• D. Ventricular muscle cells

Correct answer: D

Rationale: The QRS complex on an ECG represents ventricular depolarization. This electrical activity is generated by the ventricular muscle cells. While the SA node generates the P wave, the AV node delays the impulse, and the Bundle of His and Purkinje fibers assist in rapidly conducting the impulse through the ventricles, it is the ventricular muscle cells that specifically create the QRS complex. Therefore, choice D, Ventricular muscle cells, is the correct answer. Choices A, B, and C are incorrect as they are primarily involved in initiating and coordinating the electrical impulses in the heart but do not directly generate the QRS complex on an ECG.

2. What is the primary function of the pyloric sphincter?

• A. to regulate the movement of food material from the stomach to the duodenum
• B. to neutralize stomach acid
• C. to prevent digested food materials and stomach acid from entering the esophagus
• D. to begin the process of chemical digestion

Correct answer: A

Rationale: The primary function of the pyloric sphincter is to regulate the flow of partially digested food material (chyme) from the stomach into the small intestine, specifically the duodenum. This control is essential for proper digestion and absorption of nutrients in the small intestine. Choices B, C, and D are incorrect. Choice B is incorrect because neutralizing stomach acid is primarily the function of the stomach lining and antacid mechanisms. Choice C is incorrect because preventing the backflow of digested food materials and stomach acid into the esophagus is mainly the role of the lower esophageal sphincter. Choice D is incorrect because the chemical digestion process primarily starts in the stomach through the action of gastric juices, not the pyloric sphincter.

3. Which of the following is a function of the liver?

• A. Producing digestive enzymes
• B. Storing bile
• C. Filtering waste products from the blood
• D. Transporting nutrients to cells

Correct answer: B

Rationale: The correct function of the liver is to store bile. Bile is produced in the liver and stored in the gallbladder until it is needed to aid in the digestion of fats. While the liver does produce bile, its primary role is to store and release it. Choices A, C, and D are incorrect. Producing digestive enzymes is mainly the function of the pancreas, filtering waste products from the blood is primarily done by the kidneys, and transporting nutrients to cells is typically associated with the circulatory system rather than the liver.

4. Which muscles play a significant role in the process of forced exhalation by contracting to reduce the thoracic cavity volume?

• A. Diaphragm
• B. External intercostal muscles
• C. Internal intercostal muscles
• D. Abdominal muscles

Correct answer: D

Rationale: The abdominal muscles play a significant role in forced exhalation by contracting to reduce the thoracic cavity volume. When these muscles contract, the pressure within the thoracic cavity increases, assisting in the expulsion of air from the lungs. This action helps to compress the abdomen and push the diaphragm upwards, further decreasing the volume of the thoracic cavity and aiding in the exhalation process. The diaphragm (Choice A) is mainly involved in inhalation by contracting and moving downward to increase thoracic cavity volume. External intercostal muscles (Choice B) and internal intercostal muscles (Choice C) are primarily involved in the process of inhalation by expanding the thoracic cavity during normal breathing, rather than forced exhalation.

5. During gas exchange in the alveoli, what happens to oxygen?

• A. Oxygen is released from the alveoli into the bloodstream.
• B. Oxygen is absorbed from the alveoli into the bloodstream.
• C. Oxygen is converted into carbon dioxide.
• D. Oxygen is stored in the alveoli for later use.

Correct answer: B

Rationale: During gas exchange in the alveoli, oxygen is absorbed from the alveoli into the bloodstream. This process occurs due to the difference in partial pressures of oxygen between the alveoli and the bloodstream, causing oxygen to move from an area of higher concentration (alveoli) to an area of lower concentration (bloodstream). Oxygen is then transported by red blood cells to tissues throughout the body for cellular respiration. Choice A is incorrect as oxygen moves from the alveoli into the bloodstream, not the other way around. Choice C is incorrect as oxygen is not converted into carbon dioxide during gas exchange. Choice D is incorrect as oxygen is not stored in the alveoli but rather continuously exchanged with carbon dioxide during respiration.

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