The Effect a Hormone Will Have on the Target Tissue

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The Answer is The first factor that will affect free hormone concentrations within the blood is the rate of production/secretion of a hormone. The rate of release for individual hormones can be quite variable, but for the most part, the secretion rate for a particular hormone occurs at a fairly steady rate. These rates of secretion are altered by either neural or humoral signals, which can either inhibit or stimulate their secretion. An example of neural signaling involves the regulation of hypothalamic hormones. Humoral signals can be quite variable and will depend upon the function of the hormone. Thus, other hormones, ions, and/or metabolites can alter the rates of hormone secretion. These humoral signals are part of the regulation of specific hormones, such as insulin, whose secretion is modified by blood glucose or aldosterone, whose secretion is altered by high levels of potassium in the blood. At the same time, the secretion of a number of hormones occurs with a circadian rhythm, meaning that the rates of secretion vary with time of day (light -dark cycle). A second factor in the concentration of free hormones in the blood is the availability of carrier proteins. These carrier proteins stabilize hormones and prevent their degradation while also allowing lipophilic hormones to remain in aqueous solutions. Lipophilic hormones are also temporarily stored in adipose tissues until serum levels begin to decrease, thereby increasing the concentration of unbound serum albumin, which is then free to pick up more hormone.
Once a hormone binds to a receptor, it may be internalized and degraded by lysosomes within the target cell. There are a number of proteolytic enzymes within the blood that degrade hormones, however, the degradation of steroid and thyroid hormones occurs at a much lower rate due to their binding to carrier proteins in the blood. An equilibrium exists between free and bound hormones such that, as hormones are released, a proportion will become bound to a carrier protein while others remain as free hormones. At the same time, as free hormone binds to its receptor, the decrease in free hormones will cause some of the bound hormones to be released.

The Effect a Hormone Will Have on the Target Tissue

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