Chapter 15 - Section 15.1 - General Properties of the Autonomic Nervous System - Before You Go On - Page 560: 2

The sympathetic division and the parasympathetic division are two branches of the autonomic nervous system (ANS) that have opposing effects on various physiological processes in the body. Here's how their general effects differ: 1. Sympathetic Division: - **"Fight or Flight" Response:** The sympathetic division is often associated with the "fight or flight" response, which prepares the body for action in response to stress or danger. - **Pupil Dilation:** Sympathetic activation causes the pupils of the eyes to dilate (widen), allowing more light to enter the eyes for improved vision. - **Increased Heart Rate:** Sympathetic stimulation leads to an increase in heart rate and the force of cardiac contractions, preparing the body for increased physical activity. - **Bronchodilation:** The bronchi in the lungs dilate, allowing for increased airflow and oxygen uptake. - **Mobilization of Energy:** It promotes the release of glucose from the liver into the bloodstream, providing a quick energy source for muscles. - **Inhibition of Digestion:** Digestive processes are inhibited during sympathetic activation to divert resources away from non-essential functions. - **Stimulation of Sweat Glands:** Sweating increases to help regulate body temperature during exertion. - **Peripheral Vasoconstriction:** Blood vessels in non-essential areas, such as the skin and digestive organs, constrict to divert blood flow to the muscles and vital organs. 2. Parasympathetic Division: - **"Rest and Digest" Response:** The parasympathetic division is often associated with the "rest and digest" response, promoting relaxation and recovery. - **Pupil Constriction:** Parasympathetic activation causes the pupils to constrict (narrow), reducing the amount of light entering the eyes. - **Decreased Heart Rate:** Heart rate decreases as the parasympathetic system opposes the sympathetic effects, promoting a slower, more restful state. - **Bronchoconstriction:** The bronchi in the lungs constrict, reducing airflow and allowing for a more relaxed state. - **Stimulation of Digestion:** Digestive processes are stimulated during parasympathetic activation, promoting nutrient absorption and digestive function. - **Promotion of Energy Storage:** The parasympathetic division encourages the storage of energy reserves, such as glycogen in the liver. - **Relaxation and Restoration:** It fosters relaxation, repair, and restoration of bodily functions during periods of rest. In summary, the sympathetic division prepares the body for immediate action and responds to stress or challenging situations by increasing alertness and energy expenditure. In contrast, the parasympathetic division promotes relaxation, energy conservation, and recovery, facilitating the body's normal maintenance and repair processes during restful periods. These two divisions work in concert to maintain overall physiological balance and adapt to changing environmental demands.

The sympathetic division and the parasympathetic division are two branches of the autonomic nervous system (ANS) that have opposing effects on various physiological processes in the body. Here's how their general effects differ: 1. Sympathetic Division: - **"Fight or Flight" Response:** The sympathetic division is often associated with the "fight or flight" response, which prepares the body for action in response to stress or danger. - **Pupil Dilation:** Sympathetic activation causes the pupils of the eyes to dilate (widen), allowing more light to enter the eyes for improved vision. - **Increased Heart Rate:** Sympathetic stimulation leads to an increase in heart rate and the force of cardiac contractions, preparing the body for increased physical activity. - **Bronchodilation:** The bronchi in the lungs dilate, allowing for increased airflow and oxygen uptake. - **Mobilization of Energy:** It promotes the release of glucose from the liver into the bloodstream, providing a quick energy source for muscles. - **Inhibition of Digestion:** Digestive processes are inhibited during sympathetic activation to divert resources away from non-essential functions. - **Stimulation of Sweat Glands:** Sweating increases to help regulate body temperature during exertion. - **Peripheral Vasoconstriction:** Blood vessels in non-essential areas, such as the skin and digestive organs, constrict to divert blood flow to the muscles and vital organs. 2. Parasympathetic Division: - **"Rest and Digest" Response:** The parasympathetic division is often associated with the "rest and digest" response, promoting relaxation and recovery. - **Pupil Constriction:** Parasympathetic activation causes the pupils to constrict (narrow), reducing the amount of light entering the eyes. - **Decreased Heart Rate:** Heart rate decreases as the parasympathetic system opposes the sympathetic effects, promoting a slower, more restful state. - **Bronchoconstriction:** The bronchi in the lungs constrict, reducing airflow and allowing for a more relaxed state. - **Stimulation of Digestion:** Digestive processes are stimulated during parasympathetic activation, promoting nutrient absorption and digestive function. - **Promotion of Energy Storage:** The parasympathetic division encourages the storage of energy reserves, such as glycogen in the liver. - **Relaxation and Restoration:** It fosters relaxation, repair, and restoration of bodily functions during periods of rest. In summary, the sympathetic division prepares the body for immediate action and responds to stress or challenging situations by increasing alertness and energy expenditure. In contrast, the parasympathetic division promotes relaxation, energy conservation, and recovery, facilitating the body's normal maintenance and repair processes during restful periods. These two divisions work in concert to maintain overall physiological balance and adapt to changing environmental demands.