Several hormones are synthesized in the hypothalamus and transported to the anterior pituitary gland. The mechanism of transportation from hypothalamus to anterior pituitary gland is through the

a) Hormonal: This refers to the stimulation of one endocrine gland by hormones released from another gland. GnRH from the hypothalamus stimulates the anterior pituitary to release LH/FSH, which then stimulate the ovaries to secrete estrogen. Thus, this is hormonal control.

b) Neural: Neural stimulation involves direct innervation (e.g., adrenal medulla stimulated by the sympathetic nervous system), which does not apply here.

c) Negative Feedback: This refers to a regulatory mechanism, not the initial cause of estrogen secretion. Estrogen can negatively feedback on GnRH, but that’s not the mechanism being asked.

d) Humoral: Humoral stimuli refer to changes in blood levels of ions or nutrients (e.g., calcium regulating PTH), not hormones.

a) The location of the tissue or organ with respect to the circulatory path: Hormones are carried through the entire bloodstream, so all tissues are exposed. Proximity doesn’t determine responsiveness.

b) The membrane potential of the cells of the target organ: Membrane potential may affect nerve impulse conduction, but not hormone specificity.

c) the presence of the appropriate receptors on the cells of the target tissue or organ: Hormones act only on target cells that express specific receptors for them. No receptor = no response.

d) All hormones stimulate any and all cell types because hormones are powerful and nonspecific: Hormones are highly specific and only act on cells with matching receptors.