The fight-or-flight response, first identified by Walter Cannon, is the body's primary physiological reaction to a perceived threat. This response involves the coordinated activity of both the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. This built-in adaptive mechanism prepares an individual to either confront or escape a danger, thereby increasing the chances of survival by helping to maintain homeostasis.

Fight or Flight Response

- Release of adrenaline from adrenal glands

Typical Endocrine Changes During Activation of Sympathetic Nervous System

Activation of the fight-or-flight response, prompted by a surge of epinephrine and norepinephrine, initiates a cascade of physiological adjustments to prepare the body for a threat. These changes include:
* Pupil dilation
* Increased heart rate and blood pressure
* Heavy breathing and dilation of bronchi
* Perspiration
* Muscle tension
* Inhibition of digestion (causing sensations like 'butterflies in the stomach') and salivation
* Stimulation of glucose breakdown and release from the liver
* Relaxation of the bladder

Physiological Changes During the Fight-or-Flight Response

Based on the scenario below, which division of the nervous system is primarily responsible for orchestrating this immediate 'high-alert' state, and what is the general purpose of this response in such a situation?

Sudden Emergency Response

The sympathetic nervous system is a division of the autonomic nervous system that becomes activated in response to stressful or high-arousal situations. This activation triggers the 'fight-or-flight' response, a set of physiological changes that were evolutionarily adaptive for ancestors, enhancing their chances of survival when facing threats.

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* Sympathetic nervous system
* Parasympathetic nervous system

Subdivisions of the Autonomic Nervous System

The autonomic nervous system is a division of the peripheral nervous system that manages the body's internal organs and glands. Its functions are generally considered to be involuntary and operate outside of conscious control.

The Autonomic Nervous System

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

The Sympathetic Nervous System

A part of the autonomic nervous system that controls rest among other routine functions. It is also associated with returning the body to a relaxed state.

The Parasympathetic Nervous System

The sympathetic and parasympathetic divisions of the autonomic nervous system have complementary functions. The sympathetic system prepares the body for stress-related 'fight-or-flight' activities, while the parasympathetic system is responsible for returning the body to routine 'rest-and-digest' operations. They work in tandem to maintain the body's internal balance.

Comparison of the Sympathetic and Parasympathetic Nervous Systems

The sympathetic and parasympathetic systems operate with complementary functions, working together in tandem to maintain the body's homeostasis, which is a state of internal equilibrium where biological conditions are kept at optimal levels.

The Sympathetic and Parasympathetic Nervous Systems' Role in Homeostasis

A student is about to give a major presentation in front of a large audience. Moments before stepping on stage, they notice their heart is racing, their breathing has become quick and shallow, and their palms are sweaty. Which of the two major subdivisions of the body's involuntary internal regulation system is most active in this situation, and why do these specific physiological changes occur?

Physiological Response to a Sudden Event

Given the following case study describing a person's physiological reaction to a sudden event, identify which division of the nervous system is primarily responsible for these automatic changes and explain your reasoning.

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