what is the primary role of the sinoatrial sa node in the heart
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Nursing Elites

HESI LPN

HESI PN Exit Exam

1. What is the primary role of the sinoatrial (SA) node in the heart?

Correct answer: A

Rationale: The correct answer is A: Pacemaker of the heart. The SA node, known as the natural pacemaker, initiates the electrical impulses that set the rhythm for the heartbeat. It is responsible for coordinating the heart's contractions by generating electrical signals at regular intervals. Choice B is incorrect as the SA node's primary function is not related to blood pressure regulation. Choice C is incorrect as the SA node does not cause electrical conduction delay but rather initiates and conducts the electrical impulses. Choice D is incorrect as the SA node does not directly stimulate muscle contraction but rather initiates the electrical events that lead to muscle contraction.

2. What is the most common cause of hyperthyroidism?

Correct answer: A

Rationale: Corrected Rationale: Graves' disease is the most common cause of hyperthyroidism. It is characterized by an overactive thyroid gland due to autoantibodies stimulating the thyroid. Hashimoto's thyroiditis is actually a cause of hypothyroidism, not hyperthyroidism. Thyroid nodules and pituitary adenoma are not common causes of hyperthyroidism.

3. A full-term, 24-hour-old infant in the nursery regurgitates and suddenly turns cyanotic. Which immediate intervention should the PN implement?

Correct answer: C

Rationale: Suctioning the oral and nasal passages is the correct immediate intervention in this scenario. Regurgitation leading to cyanosis indicates a potential airway obstruction, which requires prompt action to clear. Stimulating the infant to cry (Choice A) may not address the underlying issue of airway obstruction. Giving oxygen by positive pressure (Choice B) can be beneficial, but clearing the airway obstruction takes precedence. Turning the infant onto the right side (Choice D) does not directly address the need to clear the airway.

4. Which condition is characterized by a progressive loss of muscle strength due to an autoimmune attack on acetylcholine receptors?

Correct answer: A

Rationale: The correct answer is A: Myasthenia gravis. Myasthenia gravis is characterized by muscle weakness caused by autoimmune attack on acetylcholine receptors at the neuromuscular junction. This results in impaired communication between nerves and muscles. Choice B, Multiple sclerosis, is a condition where the immune system attacks the protective myelin sheath covering the nerves in the central nervous system, leading to communication issues between the brain and the rest of the body. Choice C, Amyotrophic lateral sclerosis, is a progressive neurodegenerative disease affecting motor neurons in the brain and spinal cord, not involving acetylcholine receptors. Choice D, Guillain-Barré syndrome, is an acute condition where the immune system attacks the peripheral nerves, causing muscle weakness and paralysis, but it does not target acetylcholine receptors.

5. What is the primary purpose of administering Rho(D) immune globulin (RhoGAM) to an Rh-negative mother after childbirth?

Correct answer: A

Rationale: The correct answer is A: To prevent Rh sensitization in future pregnancies. RhoGAM is given to an Rh-negative mother to prevent the development of antibodies against Rh-positive blood cells. This prevents Rh sensitization, which could lead to hemolytic disease in future Rh-positive pregnancies. Choices B, C, and D are incorrect because RhoGAM is not used to treat anemia in the newborn, increase the mother's white blood cell count, or prevent infection in the newborn.

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