Which patient is at the greatest risk for developing pressure ulcers?

Correct Answer: C

Rationale: In this scenario, the correct answer is option C) a 30-year-old man who is comatose following a head injury. This patient is at the greatest risk for developing pressure ulcers due to immobility and decreased sensation, which are significant risk factors for pressure ulcer development. Option A) is an obese woman with type 2 diabetes, which does increase the risk for pressure ulcers, but not as significantly as immobility and decreased sensation seen in comatose patients. Option B) is a confused and malnourished 78-year-old man, who is at risk for pressure ulcers due to malnutrition and confusion leading to inadequate self-care, but again, immobility is a greater risk factor. Option D) a 65-year-old woman with urge and stress incontinence, while at risk for skin breakdown due to incontinence, does not have the same level of risk as the comatose patient. Educationally, understanding the risk factors for pressure ulcers is crucial for healthcare providers to prevent their development in at-risk patients. Immobility, decreased sensation, poor nutrition, and incontinence are all important factors to consider when assessing a patient's risk for pressure ulcers. Proper skin assessment, repositioning, moisture management, and nutrition are key components of pressure ulcer prevention in clinical practice.

Correct Answer: A

Rationale: The correct answer is A) It is captured, processed, and presented to a lymphocyte by a macrophage. Explanation of why it is correct: When an antigen enters the body, macrophages, a type of immune cell, capture and process the antigen. They then present fragments of the antigen on their surface to lymphocytes, specifically T cells. This presentation activates the T cells, initiating an immune response against the specific antigen. Explanation of why others are wrong: B) Antigens do not circulate in the blood to come in contact with circulating lymphocytes directly. They need to be processed and presented by antigen-presenting cells like macrophages. C) While antigens are indeed foreign proteins with unique determinants, this option does not explain how the immune response is activated. D) Antigens do not necessarily combine with larger molecules to stimulate antibody production directly. The process involves antigen presentation to lymphocytes to trigger antibody production. Educational context: Understanding how antigens stimulate immune responses is crucial in pharmacology as it underpins the rationale for vaccine development, immunotherapy, and understanding autoimmune diseases. Knowing the role of antigen presentation by macrophages helps pharmacology students grasp the initial steps of immune activation, highlighting the importance of antigen recognition in immune responses.

Correct Answer: C

Rationale: The correct answer is C) Sensitized T lymphocytes attack antigens or release cytokines that attract macrophages that cause tissue damage. In the context of a type IV or delayed hypersensitivity transplant reaction, sensitized T lymphocytes play a crucial role. These T lymphocytes recognize the specific antigen present in the transplanted tissue as foreign and initiate an immune response. When sensitized T cells encounter the antigen, they release cytokines that attract macrophages to the site. These macrophages cause tissue damage through inflammation and destruction of the transplanted tissue. Option A is incorrect because it describes a type I hypersensitivity reaction mediated by IgE antibodies and mast cells, not a type IV reaction involving T lymphocytes. Option B is incorrect as it describes a type II hypersensitivity reaction where complement-mediated cellular lysis or phagocytosis occurs, not a delayed hypersensitivity reaction involving T lymphocytes. Option D is incorrect as it refers to immune complex-mediated type III hypersensitivity reactions involving IgG and IgM antibodies, not a T cell-mediated type IV reaction. Understanding the mechanisms of different types of hypersensitivity reactions is essential in pharmacology to differentiate between immune responses and tailor appropriate treatment strategies for patients experiencing these reactions.

Correct Answer: D

Rationale: The correct answer to the question is D) Cytotoxic antibodies to the donor contraindicate transplanting this donor’s organ. This is because a positive crossmatch test indicates the presence of antibodies in the recipient's blood that react against the donor's human leukocyte antigens (HLA), which are present on the surface of cells. These antibodies can lead to rejection of the transplanted organ by causing damage to the donor's cells. Option A) Matches tissue types for a successful transplantation is incorrect because a positive crossmatch actually indicates a mismatch between the recipient and donor, making it less likely for a successful transplantation to occur. Option B) Determines paternity and predicts risk for certain diseases and Option C) Establishes racial background and predicts risk for certain diseases are both unrelated to the purpose of a crossmatch test, which is specifically done to assess compatibility for organ transplantation. In an educational context, understanding the significance of a crossmatch test is crucial in the field of pharmacology, especially in the context of organ transplantation and immunosuppressive therapy. This knowledge is essential for healthcare professionals involved in the care of transplant patients to ensure proper assessment of compatibility and reduce the risk of organ rejection.

Correct Answer: A

Rationale: In this scenario, the correct answer is A) Mask. When a patient has Haemophilus influenzae, a respiratory pathogen, the nurse should wear a mask when working within 3 feet of the patient to prevent the transmission of respiratory droplets containing the bacteria. The mask acts as a barrier, reducing the risk of inhaling infectious particles. Gown (B), gloves (C), and shoe covers (D) are not necessary in this situation as Haemophilus influenzae is primarily transmitted through respiratory droplets and does not require contact precautions like gowns, gloves, or shoe covers. Educationally, this question reinforces the importance of understanding specific precautions for different infectious agents. It highlights the significance of proper infection control practices in healthcare settings to prevent the spread of infections among patients and healthcare workers. Understanding when to use different personal protective equipment is crucial for ensuring a safe and healthy environment for all individuals involved.