Which of the following is the most common risk factor for the development of ovarian cancer?

Correct Answer: A

Rationale: Nulliparity, which refers to never having given birth to a child, is the most common risk factor for the development of ovarian cancer. Women who have never been pregnant have a higher risk of developing ovarian cancer compared to those who have had children. This association is believed to be related to the uninterrupted ovulation cycles that nulliparous women experience, leading to changes in the surface epithelium of the ovary that predispose them to cancer development. Conversely, factors like early menarche, late menopause, and a family history of breast cancer are also associated with an increased risk of ovarian cancer but are not as commonly observed as nulliparity in the general population.

Correct Answer: A

Rationale: Natural killer (NK) cells play a vital role in the innate immune response by identifying and eliminating virus-infected cells, as well as tumor cells, without the need for prior exposure or activation. NK cells are able to detect abnormal cells by recognizing changes in the cell surface molecules, such as downregulation of MHC class I molecules. Once activated, NK cells release cytotoxic granules containing perforin and granzyme, leading to the destruction of the target cell. This direct killing mechanism is crucial for controlling viral infections and preventing the development of tumors. NK cells do not produce antibodies (option B), present antigens to T cells (option C), or release cytokines to recruit other immune cells (option D) as their primary function in the immune response.

Correct Answer: A

Rationale: T helper cells (Th cells) are primarily responsible for coordinating and regulating immune responses by producing cytokines that direct the activities of other immune cells. These cytokines help in activating cytotoxic T cells, B cells, macrophages, and other cells involved in the immune response. Th cells play a crucial role in mounting an effective immune response against infections and diseases by providing the necessary signals to activate and control various immune cells. Thus, T helper cells are considered the central coordinators of the immune system.

Correct Answer: A

Rationale: Albuterol (salbutamol) is a short-acting beta agonist bronchodilator commonly used for quick relief of bronchoconstriction in patients with COPD. It works by relaxing the smooth muscles in the airways, allowing for easier breathing and improved airflow. The patient's increased dyspnea, wheezing, and productive cough are indicative of bronchoconstriction, and albuterol is the most appropriate medication to provide rapid bronchodilation and symptom relief in this situation. Diphenhydramine (Benadryl) is an antihistamine and not typically used for bronchodilation in COPD. Montelukast (Singulair) is a leukotriene receptor antagonist that may be used in the maintenance treatment of COPD but is not the initial choice for acute symptom relief. Prednisone is a cortic

Correct Answer: D

Rationale: Cor pulmonale is a condition characterized by right heart failure secondary to pulmonary hypertension, which is often caused by chronic hypoxemia. Chronic hypoxemia occurs in conditions such as chronic obstructive pulmonary disease (COPD) where there is limited airflow in and out of the lungs, leading to low oxygen levels in the blood. However, the specific characteristic of pulmonary hypertension leading to right heart failure distinguishes cor pulmonale from COPD. Other conditions like idiopathic pulmonary fibrosis (IPF) and pulmonary embolism (PE) may also lead to hypoxemia but are not primarily associated with pulmonary hypertension and right heart failure as in cor pulmonale.