Without regular supplies of some hormones our capacity to behave would be seriously impaired; without others we would soon die. Tiny amounts of some hormones can modify moods and actions, our inclination to eat or drink, our aggressiveness or submissiveness, and our reproductive and parental behavior. And hormones do more than influence adult behavior; early in life they help to determine the development of bodily form and may even determine an individuals behavioral capacities. Later in life the changing outputs of some endocrine glands and the bodys changing sensitivity to some hormones are essential aspects of the phenomena of aging.
Communication within the body and the consequent integration of behavior were considered the exclusive province of the nervous system up to the beginning of the present century. The emergence of endocrinology as a separate discipline can probably be traced to the experiments of Bayliss and Starling on the hormone secretion. This substance is secreted from cells in the intestinal walls when food enters the stomach; it travels through the bloodstream and stimulates the pancreas to liberate pancreatic juice, which aids in digestion. By showing that special cells secret chemical agents that are conveyed by the bloodstream and regulate distant target organs or tissues. Bayliss and starling demonstrated that chemical integration could occur without participation of the nervous system.
The term hormone was first used with reference to secretion. Starling derived the term from the Greek hormone, meaning to excite or set in motion. The term endocrine was introduced shortly thereafter Endocrine is used to refer to glands that secret products into the bloodstream. The term endocrine contrasts with exocrine, which is applied to glands that secret their products though ducts to the site of action. Examples of exocrine glands are the tear glands, the sweat glands, and the pancreas, which secrets pancreatic juice through a duct into the intestine. Exocrine glands are also called duct glands, while endocrine glands are called ductless.
1.What is the authors main purpose in the passage?
A.To explain the specific functions of various hormones.
B.To provide general information about hormones.
C.To explain how the term hormone evolved.
D.To report on experiments in endocrinology.
2.The passage supports which of the following conclusions?
A.The human body requires large amounts of most hormones.
B.Synthetic hormones can replace a persons natural supply of hormones if necessary.
C.The quantity of hormones produced and their effects on the body are related to a persons age.
D.The short child of tall parents very likely had a hormone deficiency early in life.
3.It can be inferred from the passage that before the Bayliss and Starling experiments, most people believed that chemical integration occurred only___.
A.during sleep.
B.in the endocrine glands.
C.under control of the nervous system.
D.during strenuous exercise.
4.The word liberate could best be replaced by which of the following?
A.Emancipate
B.Discharge
C.Surrender
D.Save
5.According to the passage another term for exocrine glands is___.
A.duct glands
B.endocrine glands
C.ductless glands
D.intestinal glands.
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