人体中的所有结构共同发挥作用以维持体内平衡，
这是人体根据外部环境维持内部环境的一个过程。
人体如何维持平衡的例子包括
肝脏对药物和毒素的代谢、
肾脏对血液中水分和溶质的调节、
胰腺对血糖的调节。
另一个平衡过程是热调节，
即维持正常体温
如果人体的皮肤或核心温度下降，
皮肤或内脏器官中的体温感受器就会向下丘脑发出冲动，
而下丘脑则充当人体的恒温器
下丘脑通过交感神经系统做出反应，
收缩皮肤血管
血管收缩使血液从皮肤和四肢流向更温暖的身体内部，
以防止热量进一步散失到周围环境中，
并防止身体的核心温度进一步下降
髂前肌收缩，
导致毛囊勃起，试图将温暖的空气阻挡在皮肤旁
体温持续下降会促使下丘脑发出冲动，
引起骨骼肌的颤抖反射，
产生额外的热量以提高体温。
如果身体的皮肤或核心温度升高，
皮肤或内脏器官中的体温感受器会促使下丘脑停止对皮肤血管的交感刺激
血管扩张，让温暖的血液通过皮肤散发热量
髂前肌放松，毛囊平贴皮肤
汗腺分泌汗液，使热量通过蒸发散失
体温的刺激或降低会使大脑充当恒温器，
将热量散发到全身各处
一旦达到正常温度，恒温器就会关闭
这些身体对抗刺激的反应
被称为负反馈回路
它使身体保持平衡

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All structures in the body function together to maintain homeostasis
人体中的所有结构共同发挥作用以维持体内平衡,
a process by which the body maintains its internal environment in response to the external environment
这是人体根据外部环境维持内部环境的一个过程·
Examples of how the body maintains homeostasis include
人体如何维持平衡的例子包括
metabolism of drugs and toxins in the liver
肝脏对药物和毒素的代谢、
regulation of water and solutes in the blood by the kidneys
肾脏对血液中水分和溶质的调节、
regulation of blood glucose by the pancreas
胰腺对血糖的调节·
Another homeostatic process thermal regulation
另一个平衡过程是热调节,
is the maintenance of normal body temperature
即维持正常体温
If the body's skin or core temperature drops
如果人体的皮肤或核心温度下降,
thermoreceptors in the skin or internal organs send impulses to the hypothalamus
皮肤或内脏器官中的体温感受器就会向下丘脑发出冲动,
which acts as the body's thermostat
而下丘脑则充当人体的恒温器
The hypothalamus responds through the sympathetic nervous system
下丘脑通过交感神经系统做出反应,
by constricting blood vessels in the skin
收缩皮肤血管
Vasoconstriction diverts blood away from the skin and extremities
血管收缩使血液从皮肤和四肢流向更温暖的身体内部,
to the warmer interior of the body to prevent further loss of heat to the surroundings
以防止热量进一步散失到周围环境中,
and prevent the body's core temperature from dropping further
并防止身体的核心温度进一步下降
Arrector pili muscles contract
髂前肌收缩,
causing piloerections in which hair follicles stand up in an attempt to trap warm air next to the skin
导致毛囊勃起,试图将温暖的空气阻挡在皮肤旁
A continued drop in temperature prompts the hypothalamus
体温持续下降会促使下丘脑发出冲动,
to send impulses that elicit a shivering reflex in skeletal muscles
引起骨骼肌的颤抖反射,
generating additional heat to increase body temperature
产生额外的热量以提高体温·
If the body's skin or core temperature increases
如果身体的皮肤或核心温度升高,
thermoreceptors in the skin or internal organs prompt the hypothalamus to halt sympathetic stimulation of blood vessels in the skin
皮肤或内脏器官中的体温感受器会促使下丘脑停止对皮肤血管的交感刺激
The vessels dilate and allow warm blood to distribute heat through the skin
血管扩张,让温暖的血液通过皮肤散发热量
Arrector pili muscles relax and hair follicles lie flat against the skin
髂前肌放松,毛囊平贴皮肤
Sweat glands produce sweat allowing heat loss through evaporation
汗腺分泌汗液,使热量通过蒸发散失
The stimulus or decrease in body temperature causes the brain to act as a thermostat
体温的刺激或降低会使大脑充当恒温器,
and dissipate heat throughout the body
将热量散发到全身各处
Once normal temperature is reached the thermostat shuts off
一旦达到正常温度,恒温器就会关闭
These examples of the body's response to counteract stimuli
这些身体对抗刺激的反应
are called negative feedback loops
被称为负反馈回路
which allows the body to maintain homeostasis
它使身体保持平衡