The levels of hormones circulating in blood are tightly regulated This is especially true for most peptide hormones which have a short half-life in blood. The blood level of the peptide hormone ghrelin, an appetite stimulant, changes rapidly throughout the day. Ghrelin levels peak right before a meal and drop sharply after a meal. Select the statements that describe mechanisms for rapidly altering the amount of ghrelin circulating in blood. Upon stimulation, large amounts of ghrelin are rapidly synthesized and immediately secreted into the bloodstream. Ghrelin is stored at a high concentration in the secretory vesicles of cells lining the stomach Upon stimulation, ghrelin is rapidly released from the secretory vesicles into the bloodstream Ghrelin in circulation is rapidly removed from the bloodstream by carrier proteins that bind hormones and transport them to appropriate tissues for degradation and excretion. Circulating ghrelin is rapidly removed from the bloodstream by enzymatic degradation and excretion by the liver and kidneys. After receptor binding, ghrelin is quickly cleared by adsorption to insoluble fiber moving through the stomach.