Epinephrine

Definition

Epinephrine, also known as adrenaline, is a hormone and neurotransmitter produced by the adrenal glands. It plays a crucial role in the body’s fight-or-flight response, increasing heart rate, blood pressure, and energy supplies during stressful situations. As a neurotransmitter, it is involved in synaptic transmission, acting on adrenergic receptors to modulate various physiological processes.

5 Must Know Facts For Your Next Test

1. Epinephrine is synthesized from tyrosine in the adrenal medulla and can act as both a hormone and neurotransmitter.
2. During stress, epinephrine triggers an increase in heart rate, respiratory rate, and energy mobilization from fat and glucose stores.
3. The effects of epinephrine are mediated through its binding to adrenergic receptors, which can be classified into alpha and beta types.
4. Epinephrine can also be used as a medication in emergencies, such as anaphylactic shock, to rapidly reverse severe allergic reactions.
5. Epinephrine's rapid action is crucial for survival during acute stress, as it prepares the body to either confront or flee from danger.

Review Questions

• How does epinephrine influence synaptic transmission and what physiological effects does it trigger?
  • Epinephrine influences synaptic transmission by binding to adrenergic receptors in the nervous system. This binding initiates a cascade of biochemical events that result in increased heart rate, enhanced blood flow to muscles, and boosted energy availability. These physiological effects prepare the body to respond effectively to stressors, showcasing how epinephrine acts not only as a hormone but also as a key player in neurotransmission.
• Compare and contrast the roles of epinephrine and norepinephrine in the sympathetic nervous system.
  • Both epinephrine and norepinephrine are critical to the sympathetic nervous system's response to stress. While epinephrine primarily functions as a hormone released from the adrenal glands to trigger widespread effects throughout the body, norepinephrine acts mainly as a neurotransmitter within the central nervous system. Together, they enhance alertness and physical readiness by increasing heart rate, blood pressure, and energy metabolism but do so through different mechanisms and pathways.
• Evaluate how understanding epinephrine's function can impact medical treatments for stress-related disorders.
  • Understanding epinephrine's function is crucial for developing effective medical treatments for stress-related disorders such as anxiety or PTSD. By recognizing how this neurotransmitter affects the body's stress response, clinicians can better target therapies that mitigate its excessive effects. For instance, medications that block adrenergic receptors can help manage symptoms by reducing the physiological impact of stress, thereby improving quality of life for patients facing these challenges.

Related terms

Norepinephrine: A neurotransmitter closely related to epinephrine, which plays a key role in attention, emotions, and the body's response to stress.

Adrenergic Receptors: A class of receptors that respond to catecholamines like epinephrine and norepinephrine, mediating various physiological effects such as increased heart rate and dilation of air passages.

Sympathetic Nervous System: A division of the autonomic nervous system that prepares the body for 'fight or flight' responses, primarily through the release of epinephrine and norepinephrine.