Which hormone released by the hypothalamus directly influences the pituitary's secretion of thyroid-stimulating hormone (TSH)?

A. Defending against infections:Red blood cells do not have immune functions; defense against infection is primarily the role of white blood cells.
B. Clotting blood:Clotting is mainly mediated by platelets and clotting factors in plasma, not by red blood cells.
C. Transporting oxygen:Red blood cells contain hemoglobin, which binds oxygen in the lungs and carries it to tissues — their primary function.
D. Carrying nutrients:Nutrient transport is primarily performed by plasma (dissolved nutrients) and the digestive/transport systems, not red blood cells.

A. Adrenocorticotropic hormone (ACTH):ACTH stimulates the adrenal cortex to secrete cortisol; overproduction of ACTH causes Cushing disease features rather than the soft-tissue/bone overgrowth seen in acromegaly.
B. Prolactin:Prolactin excess causes galactorrhea and reproductive disturbances; it does not produce the characteristic enlarged hands, feet, and facial features of acromegaly.
C. Thyroid-stimulating hormone (TSH):Excess TSH leads to hyperthyroidism, which causes metabolic and sympathetic symptoms, not the skeletal overgrowth typical of acromegaly.
D. Growth hormone (GH):Excess GH from a pituitary adenoma stimulates increased IGF-1 production, promoting soft-tissue and bone growth that leads to the characteristic enlargement of the hands, feet, and facial bones in acromegaly.