Structure and Function of the Endocrine System
内分泌系统的结构与功能
The endocrine system provides communication within the body and helps to regulate growth and development, reproduction, energy use, and electrolyte balance. The endocrine system is closely interconnected with the nervous system, and the two systems work to maintain homeostasis within the body to ensure maximum function and adequate response to various internal and external stressors.
Hormones are chemicals that are produced in the body and that meet specific criteria. All hormones:
激素是机体产生并满足特定标准的化学物质。所有激素
Are produced in very small amounts
产生数量极小
Are secreted directly into the bloodstream
直接分泌进入血流
Travel through the blood to specific receptor sites throughout the body
流经身体到全身特定受体部位
Act to increase or decrease the normal metabolic cellular processes when they react with their specific receptor sites
其作用是，与特定受体部位反应，增加或减少正常的代谢性细胞过程
Are immediately broken down
立即分解
Hormones may act in two different ways. Some hormones react with specific receptor sites on a cell membrane to stimulate the nucleotide cyclic adenosine monophosphate (cyclic AMP) within the cell to cause an effect. For example, when insulin reacts with an insulin receptor site, it activates intracellular enzymes that cause many effects, including changing the cell membrane’s permeability to glucose. Hormones such as insulin that do not enter the cell but react with specific receptor sites on the cell membrane act very quickly—often within seconds—to produce an effect.
Other hormones, such as estrogen, actually enter the cell and react with a receptor site inside the cell to change messenger RNA, which enters the cell nucleus to affect cellular DNA and thereby alters the cell’s function. These hormones that enter the cell before they can cause an effect take quite a while to produce an effect. The full effects of estrogen may not be seen for months to years, as evidenced by the changes that occur at puberty. Because the neuroendocrine system tightly regulates the body’s processes within a narrow range of normal limits, overproduction or underproduction of any hormone can affect the body’s activities and other hormones within the system.
The endocrine system and the nervous system regulate body functions and maintain homeostasis largely with the help of hormones, which are chemicals produced within the body. Hormones increase or decrease cellular activity.
The endocrine system regulates growth and development, reproduction, energy use in the body, and electrolyte balance.
内分泌系统调节生长和发育、生殖、机体能量使用和电解质平衡。
Hormones can react with receptors on the cell membrane to cause an immediate effect on a cell by altering enzyme systems near the cell membrane or they may enter the cell and react with receptor sites on messenger RNA, which then enters the nucleus and alters cell function.
endocrine – n. a. 内分泌（的）
endocrine system – 内分泌系统
communication – n. 沟通，信息传递
interconnect – v. 使相互联系，互边
homeostasis – n. 内稳态，内环境稳定
stressor – n. 应激源，应激因子
hormone – n. 激素，荷尔蒙
secrete – v. 分泌
nucleotide – n. 核苷酸
cyclic adenosine monophosphate – 环磷腺苷
cyclic – a. 循环的，环状的
AMP – adenosine monophosphate腺苷酸
adenosine – n. 腺苷
monophosphate – n. 单磷酸，一磷酸
permeability – n. 渗透性
glucose – n. 葡萄糖
estrogen – n. 雌激素
messenger – n. 信使
RNA – n. 核糖核酸
DNA – n. 脱氧核糖核酸
neuroendocrine – n. 神经内分泌
overproduction – n. 生产过剩
underproduction – n. 生产不足
chemical – n. 化学药品，化学物质
1. Glands are small organs located throughout your body that secrete substances called:
A. Plasma
B. Hormones
C. Enzymes
D. Bile 2. Hormones help your body by:
A. Telling your cells what to do
B. Helping you breathe
C. Sending nerve messages
D. Oxidizing your blood 3. Which of the following is not part of the endocrine system?
A. Thyroid
B. Adrenals
C. Appendix
D. Pituitary
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