Which of the following hormones stimulates the proliferation of red blood cells in red bone marrow?

a) store iron in the liver: Ferritin is an intracellular protein that stores iron and releases it in a controlled fashion. It is primarily found in the liver, spleen, and bone marrow.

b) Absorb iron across intestinal cells: DMT1 (divalent metal transporter 1) and ferroportin are more directly involved in this.

c) Oxidize iron in the peroxisomes: Iron oxidation is not a function of peroxisomes, nor of ferritin.

d) Transport iron in the blood: Transferrin, not ferritin, is responsible for iron transport in plasma.

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.