autonomic nervous system
Introduction to the Autonomic Nervous System
In this course, we will learn to describe the structure and function of the sympathetic and parasympathetic nervous systems.
在本课程中，我们将学习描述交感神经系统和副交感神经系统的结构与功能。
The autonomic nervous system is responsible for unconscious activities of the body, functioning whether we are awake or asleep.
自主神经系统负责身体的无意识活动，无论我们是否在睡觉，它都在运作。
This system not only helps us escape dangerous situations but also promotes food digestion.
该系统不仅帮助我们逃避危险情况，还能促进食物的消化。
Key Term: Nervous System
Nervous System: A network of nerve cells that transmit nerve impulses between different parts of the body.
神经系统：神经细胞构成的网络，负责在身体各部位之间传递神经冲动。
Main Divisions of the Nervous System
The nervous system is mainly divided into two parts:
神经系统主要分为两部分：
Central Nervous System (CNS)
中枢神经系统 (CNS)
Includes the brain and spinal cord.
包括大脑和脊髓。
Peripheral Nervous System (PNS)
外周神经系统 (PNS)
Includes spinal nerves and cranial nerves outside the brain, responsible for transmitting information between the CNS and other parts of the body.
包括在大脑之外的脊髓神经和颅神经，负责在 C N S 和身体其他部分之间传递信息。
Key Term: Autonomic
Autonomic Nervous System: This part operates under unconscious control.
自主神经系统：该部分在无意识控制下运作。
Subdivisions of the Peripheral Nervous System
The peripheral nervous system has multiple branches, mainly including:
外周神经系统中有多个分支，主要包括：
Sensory Branch: Transmits impulses from receptors to the CNS.
感觉分支：将冲动从感受器传递给 C N S。
Motor Branch: Transmits impulses from the CNS to effector organs.
运动分支：将冲动从 C N S 传递给效应器器官。
Effector Organs: Organs that perform responses, such as muscles and glands.
效应器器官：执行反应的器官，例如肌肉和腺体。
Functions of the Autonomic Nervous System
The purpose of the autonomic nervous system is to regulate involuntary and unconscious activities.
自主神经系统的目的是调控不自觉与无意识的活动。
Sends nerve impulses to smooth muscles, cardiac muscles, and glands.
发送神经冲动至平滑肌、心脏肌肉及腺体。
Example 1: Main Role of the Autonomic Nervous System
示例 1：自主神经系统的主要作用
Its primary purpose is to regulate involuntary activities, not to control voluntary movements.
主要目的是调控不自愿的活动，而不是控制自愿运动。
Sympathetic and Parasympathetic Nervous Systems
Comparison and Contrast: The sympathetic and parasympathetic nervous systems are antagonistic systems.
比较与对比：交感神经系统与副交感神经系统是对抗性的系统。
They often elicit opposite responses (e.g., increase or decrease in heart rate) to maintain the stability of the internal environment, i.e., homeostasis.
它们通常引起相反的反应（例如心率的增加或减少），以维持内部环境的稳定，即稳态。
Sympathetic Nervous System: Prepares the body for coordinated action.
交感神经系统：为身体做好协调行动的准备。
Parasympathetic Nervous System: Brings the body back to a peaceful resting state.
副交感神经系统：将身体带回和平的休息状态。
Illustration: Effects of sympathetic and parasympathetic nerves on different organs.
图示：交感神经和副交感神经对不同器官的影响。
Parasympathetic Nervous System
The nerve fibers of the parasympathetic nervous system originate from the CNS, specifically in the brainstem and the bottom region of the spinal cord.
副交感神经系统的神经纤维起源于 C N S，具体在脑干和脊髓的底部区域。
The parasympathetic nervous system is responsible for the body's rest and digest response.
副交感神经系统负责身体的休息与消化反应。
For example, nerve impulses are sent to the stomach, stimulating the secretion of gastric juice.
例如，神经冲动发送至胃，刺激胃分泌胃液。
Signals are sent to the small intestine to increase the production of digestive enzymes; to salivary glands to increase saliva secretion; and to the liver to increase bile production.
发送信号至小肠，增加消化酶的产生；发送至唾液腺，增加唾液分泌；发送至肝脏，增加胆汁生成。
This system effectively transmits signals at each synapse by releasing acetylcholine as a neurotransmitter.
该系统通过释放乙酰胆碱作为神经递质，在每个突触处有效传递信号。
Key Term: Parasympathetic Nervous System
Parasympathetic Nervous System: Responsible for the body's rest and digest response when the body is relaxed, resting, or eating.
副交感神经系统：负责身体的休息与消化反应，当身体放松、休息或进食时。
Sympathetic Nervous System
The nerve fibers of the sympathetic nervous system originate from the CNS, specifically in the thoracic and lumbar regions of the spinal cord.
交感神经系统的神经纤维起源于 C N S，具体在胸部和腰部脊髓区域。
This system is responsible for the body's fight-or-flight response, helping us escape or cope with dangerous situations.
该系统负责身体的战斗或逃跑反应，帮助我们逃避或应对危险情况。
Key Term: Fight-or-Flight Response
关键术语：战斗或逃跑反应
An automatic physiological reaction triggered by the sympathetic nervous system, preparing the body to deal with stressful situations.
交感神经系统触发的自动生理反应，身体准备应对压力情况。
Functions of the Sympathetic Nervous System
Increases the production of adrenaline and noradrenaline via the adrenal glands.
经由肾上腺增多肾上腺素和去甲肾上腺素的产生。
Epinephrine
肾上腺素（Epinephrine）
A hormone secreted from the adrenal glands that increases blood circulation, respiration, and carbohydrate metabolism, preparing muscles for action.
从肾上腺分泌的激素，增加血液循环、呼吸及碳水化合物代谢速度，准备肌肉运作。
Heart rate increases, cells release more energy for emergency responses; it pushes blood flow to the heart and skeletal muscles to ensure oxygen and nutrients for key organs.
心率增加，细胞释放更多能量以进行紧急反应；推动血液流向心脏和骨骼肌，以确保关键器官的氧和营养。
Conclusion
The main purpose of the autonomic nervous system is to regulate unconscious and involuntary activities.
自主神经系统的主要目的是调节无意识和非自愿活动。
Includes the parasympathetic nervous system and the sympathetic nervous system.
包括副交感神经系统和交感神经系统。
The parasympathetic nervous system is involved in rest and digest responses, generally decreasing the body's activity level.
副交感神经系统涉及休息和消化反应，通常降低身体活动水平。
The sympathetic nervous system is involved in fight-or-flight responses, generally increasing the body's activity level.
交感神经系统涉及战斗或逃跑反应，通常增加身体活动水平。