Final answer:
The sympathetic nervous system is responsible for the fight-or-flight response and increases heart rate, while the parasympathetic nervous system is associated with rest and digest and decreases heart rate.
Step-by-step explanation:
The main differences between the sympathetic and parasympathetic branches of the autonomic nervous system lie in their general functions and the type of response they elicit in the body. The sympathetic nervous system is often associated with the fight-or-flight response. It prepares the body to react to stressful situations, such as danger or high-stakes environments, by increasing heart rate, dilating bronchioles in the lungs, dilating pupils, and mobilizing energy stores. In contrast, the parasympathetic nervous system is often described as the rest and digest system. It predominates in tranquil environments and helps maintain or restore homeostasis by slowing down the heart rate, constricting bronchioles, promoting digestion, and facilitating energy storage.
Regarding the specific options provided in the question:
- d) Sympathetic: Increases heart rate, Parasympathetic: Decreases heart rate is the correct choice that captures the opposing effects these two systems have on the heart.
- Option a) is incorrect because it reverses the roles of the two systems.
- Option b) is overly simplistic and does not accurately describe the opposing functions.
- Option c) is correct in describing the anatomical differences but does not cover the functional aspects. However, it is worth noting that sympathetic preganglionic fibers are indeed shorter than the long preganglionic fibers of the parasympathetic nervous system.