The Endocrine System-Characteristics of Hormones

Each hormone produced in the body is ____________________ . Each one is different in its chemical composition , structure , and ____________________ . Despite the differences , there are similarities in these ____________________ .
Chemically , hormones may be classified as either ____________________ or ____________________ . All of the hormones and those from the adrenal ____________________ , are proteins or protein derivatives . This means that their fundamental building blocks are ____________________ acids . Protein hormones must be administered ____________________ because they are quickly inactivated by the acid and ____________________ the stomach . These hormones must be administered by injection . Sex hormones and those from the adrenal cortex are ____________________ , which are lipid derivatives . These lipid - soluble hormones may be taken orally .

Hormones are carried by the ____________________ throughout the entire body , yet they affect only ____________________ cells . The specific cells that respond to a given hormone have ____________________ sites for that hormone . This is sort of a lock - and - key mechanism . If the key fits the lock , then the door will open . If a hormone fits the receptor site , then there will be an ____________________ . If a hormone and a receptor site do not match , then there is no ____________________ . All the cells that have receptor sites for a given hormone make up the ____________________ tissues for that hormone . In some cases , the target tissue is ____________________ in a single gland or organ . In other cases , the target tissue is diffuse and ____________________ throughout the body so that many areas are ____________________ . Hormones bring about their characteristic effects on target cells by ____________________ cellular activity .
Receptor sites may be located on the ____________________ of the cell membrane to in the ____________________ of the cell .

____________________ are very potent substances , which means that they are very small amounts of a hormone may have profound effects on ____________________ processes . Because of their potency , hormones secretion must be regulated within very narrow limits to maintain ____________________ in the body . Many hormones are controlled by some form of a ____________________ feedback mechanism . In this type of system , a gland is ____________________ to the concentration of a substance that it regulates . A negative feedback system causes a reversal of increases and ____________________ in body conditions to maintain a state of stability or homeostasis .
Some endocrine glands secrete hormones in response to other ____________________ . The hormones that cause secretion of other hormones are called ____________________ hormones . A hormone from gland " A " causes gland " B " to ____________________ its hormone . For example , thyroid - stimulating hormone from the ____________________ pituitary gland causes the thyroid gland to secrete the hormone ____________________ . A third method of regulating hormone secretion is by direct ____________________ stimulation . A nerve ____________________ causes a gland to secrete its hormone . A physiological example of the mechanism is the sympathetic nervous stimulation of the adrenal ____________________ , which responds by secreting epinephrine ( adrenaline . )