Nursing Elites

1. When educating a client about to undergo a pacemaker insertion, the nurse explains the normal phases of cardiac muscle tissue. During the repolarization phase, the nurse will stress that membranes must be repolarized before they can be re-excited. Within the cell, the nurse understands that:

• A. Potassium channels open while sodium channels close, causing repolarization to the resting state.
• B. The influx of calcium is the primary stimulus for the repolarization of cardiac tissue.
• C. Only the electrical activity within the heart will determine when repolarization occurs.
• D. The cell membranes need to stay calm, resulting in muscle tissue becoming refractory.

Correct answer: A

Rationale: During the repolarization phase of cardiac muscle tissue, potassium channels open while sodium channels close. This process is crucial for the cardiac muscle to return to its resting state after depolarization. Potassium moving out of the cell and sodium staying out helps reset the membrane potential and prepare the cell for the next depolarization phase. The influx of calcium is not the primary stimulus for repolarization in cardiac tissue; it is mainly involved in the depolarization phase. While electrical activity within the heart influences repolarization, the specific ion movements described in choice A are what physiologically drive repolarization. Cell membranes need to be in an active state during repolarization, not calm, to facilitate the necessary ion movements for muscle tissue to properly function.

2. A patient has developed a decubitus ulcer on the coccyx. What defense mechanism is most affected by this homeostatic change?

• A. The mucous membrane is affected.
• B. The respiratory tract is affected.
• C. The skin is affected.
• D. The gastrointestinal tract is affected.

Correct answer: C

Rationale: In this scenario, a decubitus ulcer on the coccyx indicates a breakdown of the skin's integrity due to prolonged pressure. The skin is the primary defense mechanism of the body against external pathogens. When the skin is compromised, it can lead to infections and other complications. The mucous membrane (Choice A) plays a role in protecting internal surfaces, not the skin. The respiratory tract (Choice B) is involved in breathing and not directly related to the skin's defense. The gastrointestinal tract (Choice D) is responsible for digestion and absorption of nutrients, not the primary defense mechanism against external threats like the skin.

3. What is responsible for initiating clonal selection?

• A. B cells
• B. T cells
• C. Antigens
• D. Lymphocytes

Correct answer: C

Rationale: Antigens are the correct answer as they are the molecules that trigger the immune response by binding to specific B or T cells. This binding activates these cells, leading to their proliferation and differentiation to fight off the antigen. B cells and T cells are the responders to antigens, not the initiators of clonal selection. Lymphocytes is a broad term encompassing both B and T cells, so it is not the specific factor responsible for initiating clonal selection.

4. A 55-year-old man presents with a history of fatigue, weight loss, and night sweats. He reports recent onset of a productive cough and hemoptysis. Which condition should the nurse suspect?

• A. Lung cancer
• B. Pneumonia
• C. Tuberculosis
• D. Pulmonary embolism

Correct answer: C

Rationale: The correct answer is C: Tuberculosis. The symptoms described - fatigue, weight loss, night sweats, productive cough, and hemoptysis - are classic manifestations of tuberculosis. Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, commonly affecting the lungs but can also involve other organs. **Choice A: Lung cancer** typically presents with symptoms like persistent cough, chest pain, and shortness of breath, but it is less likely in this case due to the presence of hemoptysis. **Choice B: Pneumonia** can present with productive cough, fever, and chest pain, but it is less likely given the chronicity of symptoms and the presence of hemoptysis. **Choice D: Pulmonary embolism** usually presents with sudden onset shortness of breath, chest pain, and can be associated with risk factors like recent surgery or immobility.

5. A 5-year-old female takes a hike through the woods during a school field trip. Upon returning home, she hugs her father, and he later develops poison ivy. Which of the following immune reactions is he experiencing?

• A. IgE-mediated
• B. Tissue-specific
• C. Immune complex
• D. Cell-mediated

Correct answer: D

Rationale: The father's immune reaction to poison ivy is an example of cell-mediated immunity, specifically a type IV hypersensitivity reaction. In this type of reaction, sensitized T cells react to antigens, leading to inflammation and tissue damage. IgE-mediated reactions involve antibodies of the IgE class, commonly seen in allergic responses like anaphylaxis. Tissue-specific reactions target specific organs or tissues. Immune complex reactions involve immune complexes formed by antigens and antibodies that can deposit in tissues, leading to inflammation.

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