Sympathetic Nervous System: Crash Course Anatomy & Physiology #14

Sympathetic Nervous System

Part of the nervous system that responds to stress and emergency situations, preparing the body for 'fight or flight'.

Stress Response

The physiological reaction triggered by stressors, involving changes in heart rate, breathing, and blood flow.

Acetylcholine (ACh)

A neurotransmitter released in the sympathetic nervous system at the ganglia, crucial for transmitting signals between neurons.

Norepinephrine

A neurotransmitter released from postganglionic fibers in the sympathetic nervous system and also acts as a hormone when secreted by adrenal glands.

Epinephrine

A hormone released from adrenal glands that acts alongside norepinephrine in the body's stress response.

Alpha Receptors

Receptors that, when activated by norepinephrine or epinephrine, cause smooth muscle contraction and restrict blood flow.

Beta Receptors

Receptors that, when activated, cause relaxation of smooth muscle and increase blood flow.

Parasympathetic Nervous System

The part of the autonomic nervous system that promotes relaxation and conserves energy, balancing the effects of the sympathetic nervous system.

Non-life-threatening Stress

Everyday stressors that are not immediately dangerous but still trigger similar physiological responses as life-threatening stress.

Physiological Responses

The body's automatic reactions, such as increased heart rate and faster breathing, triggered by stress and incoming signals from the nervous system.

Fight or Flight Response

The body's rapid reaction to perceived threats, triggering the sympathetic nervous system to prepare for immediate action.

Homeostasis

The state of steady internal conditions maintained by living organisms, which is disrupted during stress.

Stress Hormones

Biochemicals such as cortisol, adrenaline, and norepinephrine that are released in response to stress and affect bodily functions.

Cortisol

A steroid hormone produced by the adrenal cortex that helps regulate metabolism and the immune response during stress.

Sympathetic Postganglionic Neurons

Neurons that transmit signals from sympathetic ganglia to target organs, facilitating the fight or flight response.

Vasoconstriction

The narrowing of blood vessels, often triggered by activation of alpha receptors during a stress response.

Vasodilation

The widening of blood vessels, often triggered by activation of beta receptors, increasing blood flow to muscles and organs.

Adrenal Medulla

Inner part of the adrenal glands that secretes epinephrine and norepinephrine during stress responses.

Neural Pathways

Connected neuron networks responsible for transmitting messages throughout the nervous system, crucial for stress response processing.

Chronic Stress

A prolonged state of stress that can lead to adverse health effects such as anxiety, depression, and physical health issues.