Nokea
Which of the following tissues lines the interior surfaces of the heart?
- A. Epicardium
- B. Myocardium
- C. Endocardium
- D. Pericardium
Correct Answer: C
Rationale: The correct answer is C, Endocardium. The endocardium is the innermost layer of tissue that lines the interior surfaces of the heart, providing a smooth surface for blood flow. This smooth lining helps reduce friction as blood passes through the heart chambers. The epicardium is the outermost layer of the heart, the myocardium is the middle muscular layer responsible for the heart's contractions, and the pericardium is the protective sac surrounding the heart and providing support to the heart's structures.
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Which of the following structures is a mass within the ovary that secretes hormones to maintain the uterine lining during pregnancy?
- A. Oviduct
- B. Umbilical cord
- C. Oocyte
- D. Corpus luteum
Correct Answer: D
Rationale: The correct answer is the corpus luteum. The corpus luteum is a temporary endocrine structure in the ovary that forms after ovulation. It secretes hormones, primarily progesterone, which are essential to maintain the uterine lining during pregnancy. The other options, such as the oviduct, umbilical cord, and oocyte, do not have the function of secreting hormones to support the uterine lining in pregnancy.
Which of the following structures is an exocrine gland?
- A. Parotid gland
- B. Pituitary gland
- C. Parathyroid gland
- D. Pineal gland
Correct Answer: A
Rationale: An exocrine gland secretes substances into ducts that lead to other organs or out of the body. The parotid gland is a salivary gland that secretes saliva into the mouth through ducts, making it an exocrine gland. The pituitary gland, parathyroid gland, and pineal gland are endocrine glands, which release hormones directly into the bloodstream. Therefore, the correct answer is the Parotid gland, as it fits the definition of an exocrine gland by secreting substances through ducts.
Which of the following types of cells stimulates other immune cells to attack and destroy foreign agents?
- A. Cytotoxic T-cells
- B. Natural killer cells
- C. Helper T-cells
- D. Plasma cells
Correct Answer: C
Rationale: Helper T-cells play a crucial role in coordinating the immune response by activating and directing other immune cells, such as cytotoxic T-cells and macrophages, to attack and eliminate foreign invaders. They achieve this through the release of signaling molecules called cytokines, which regulate the immune system's response to infections and other challenges. Helper T-cells are also involved in activating B-cells to produce antibodies. Natural killer cells, on the other hand, are part of the innate immune system and can directly kill infected or abnormal cells without prior activation.
Which of the following respiratory structures is affected by a disease that disrupts gas exchange, such as emphysema?
- A. Trachea
- B. Alveoli
- C. Secondary bronchi
- D. Primary bronchi
Correct Answer: B
Rationale: Emphysema is a condition that primarily affects the alveoli in the lungs. Alveoli are tiny air sacs where the exchange of oxygen and carbon dioxide occurs. In emphysema, the walls of these air sacs break down, reducing the surface area available for gas exchange. This leads to impaired respiratory function, making it harder for oxygen to enter the bloodstream and for carbon dioxide to be removed. Therefore, the correct answer is the alveoli (Choice B).
Which of the following immune system molecules creates pores in the cell membrane of their target cells to destroy the cell?
- A. Lymphotoxins
- B. Perforins
- C. Interferons
- D. Cytokines
Correct Answer: B
Rationale: Perforins are immune system molecules that function by creating pores in the cell membrane of target cells. These pores compromise the cell's integrity, ultimately leading to cell destruction. Lymphotoxins induce cell death, but they do not create pores in the cell membrane like perforins. Interferons are signaling proteins that regulate the immune response, while cytokines are a diverse group of proteins involved in cell signaling during immune reactions. Perforins specifically target cell membranes, disrupting their integrity and leading to cell destruction, making them the correct answer in this context.