Which of the following statements is correct about aplastic anemia?

Rationale:

A. Plasma is the liquid portion of blood, making up about 55% of its volume. It consists primarily of water, electrolytes, proteins (such as albumin, globulins, and fibrinogen), hormones, and nutrients, and serves as the medium for transporting blood cells, waste products, and other substances throughout the body.

B. Platelets, or thrombocytes, are small cell fragments essential for blood clotting and hemostasis. They circulate in the plasma and aggregate at sites of vessel injury to form a temporary platelet plug, initiating the coagulation cascade.

C. Red blood cells, or erythrocytes, are the most abundant cell type in blood and are responsible for transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs. They contain hemoglobin, which binds oxygen and gives blood its red color.

D. Neurons is incorrect. Neurons are nerve cells found in the nervous system and are not a component of blood.

E. Bone cells, including osteoblasts, osteocytes, and osteoclasts, are found in bone tissue and do not circulate in the blood.

F. While bacteria may occasionally be present in the blood during infection (bacteremia), they are not a normal component of blood and their presence typically indicates a pathological condition.

Rationale:

A. Regulate red blood cell production in the bone marrow is incorrect. Red blood cell production, or erythropoiesis, is controlled by erythropoietin, a hormone secreted primarily by the kidneys in response to low oxygen levels. Goblet cells have no role in this process. They are epithelial cells specialized for mucus secretion, not involved in hematopoiesis or the regulation of blood cell production.

B. Secrete mucus to trap dust and particles in the nasal cavity is correct. Goblet cells are unicellular glands located within the epithelial lining of the respiratory and gastrointestinal tracts. Their main function is to produce mucus, a sticky secretion that traps dust, microbes, and other particles, preventing them from reaching delicate tissues. In the respiratory system, mucus works together with cilia in a process called the mucociliary escalator, which moves trapped particles upward and out of the airways to maintain pulmonary health. Goblet cells also help moisturize mucosal surfaces, protecting them from drying and injury.

C. Produce antibodies to fight infections is incorrect. Antibodies are proteins produced by B lymphocytes and plasma cells as part of the adaptive immune system. Goblet cells do not have the machinery to produce immunoglobulins or participate in specific immune responses. While mucus does provide some nonspecific immune protection by trapping pathogens, it is not involved in antibody production.

D. Generate platelets for blood clotting is incorrect. Platelets are fragments of cytoplasm derived from megakaryocytes in the bone marrow and play a critical role in hemostasis. Goblet cells are unrelated to the clotting system and do not contribute to platelet formation or blood coagulation.