Blood formation in the bone marrow and lymphatic organs is called, respectively, lymphoid and myeloid hemopoiesis.
True.
False.
Partially true.
Undetermined.
The Correct Answer is B
Choice A rationale
Hemopoiesis is the general term for blood cell formation. Myeloid hemopoiesis refers to the formation of red blood cells, granulocytes, monocytes, and platelets, which primarily occurs in the red bone marrow. Lymphoid hemopoiesis refers to the formation of lymphocytes, which occurs in lymphatic organs such as the lymph nodes, thymus, and spleen, but also significantly in the bone marrow for B-cell maturation and T-cell precursors. The statement incorrectly implies that lymphoid hemopoiesis occurs *only* in lymphatic organs and myeloid *only* in bone marrow, and the phrasing reverses their typical associations.
Choice B rationale
The statement is false. Hemopoiesis is indeed the formation of blood cells. Myeloid hemopoiesis, the formation of most blood cell types (erythrocytes, granulocytes, monocytes, platelets), predominantly occurs in the red bone marrow. Lymphoid hemopoiesis, the formation of lymphocytes, occurs in lymphoid tissues (lymph nodes, thymus, spleen) but also originates from stem cells in the bone marrow, with B cells maturing there and T cell precursors migrating to the thymus. The original statement incorrectly defines the primary sites and the relationship between lymphoid and myeloid hemopoiesis.
Choice C rationale
The statement contains fundamental inaccuracies regarding the primary sites of lymphoid and myeloid hemopoiesis. While there are overlaps and precursor origins in bone marrow for both lineages, the generalized and exclusive assignments made in the statement are incorrect, making it fully false rather than partially true.
Choice D rationale
The processes of lymphoid and myeloid hemopoiesis and their respective sites of formation are well-established scientific facts. There is no ambiguity or lack of information to render the statement "undetermined.”. The current understanding of hematopoiesis clearly refutes the claim. .
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
The pericardial cavity is the potential space between the parietal and visceral layers of the serous pericardium, containing pericardial fluid. While the heart resides within this cavity, the pericardial cavity itself is a component *within* the larger mediastinum.
Choice B rationale
The mediastinum is the central compartment of the thoracic cavity, located between the two pleural cavities. It extends from the sternum to the vertebral column and contains the heart, great vessels, trachea, esophagus, and thymus. The heart is indeed enfolded within this space.
Choice C rationale
The abdominal cavity is a large body cavity in the abdominopelvic region, containing major digestive, urinary, and reproductive organs. The heart is located in the thoracic cavity, superior to the diaphragm, and thus is not found in the abdominal cavity.
Choice D rationale
The pleural cavity refers to the potential space between the parietal and visceral pleura, surrounding each lung. There are two pleural cavities, one for each lung. The heart is situated *between* these two cavities, not within them.
Choice E rationale
The myocardium is the muscular layer of the heart wall responsible for pumping blood. It is a part of the heart itself, not a space that encloses the heart. The myocardium is covered externally by the epicardium and internally by the endocardium.
Correct Answer is A
Explanation
Choice A rationale
The pericardial fluid is a serous fluid found within the pericardial cavity, which is the space situated between the visceral pericardium (epicardium), directly adhering to the heart's surface, and the outer parietal pericardium. This fluid acts as a lubricant, reducing friction during cardiac contractions.
Choice B rationale
The myocardium is the thick muscular layer of the heart wall, and the epicardium is the visceral layer of the serous pericardium, directly covering the myocardium. There is no fluid-filled space between these two layers; they are directly continuous.
Choice C rationale
The endocardium is the innermost lining of the heart chambers, and the myocardium is the muscular layer. These layers are directly contiguous, forming the wall of the heart, without any fluid-filled space between them.
Choice D rationale
The heart and lungs are distinct organs within the thoracic cavity. While they are in close proximity, the pericardial fluid is specific to the sac surrounding the heart, not a general fluid space between the heart and the lungs.
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