Adrenal medulla

Definition

The adrenal medulla is the inner part of the adrenal glands, which are located on top of each kidney. It plays a crucial role in the body's response to stress by producing and secreting catecholamines, primarily epinephrine (adrenaline) and norepinephrine (noradrenaline). These hormones are essential for initiating the fight-or-flight response, preparing the body to react quickly to perceived threats.

5 Must Know Facts For Your Next Test

1. The adrenal medulla is primarily composed of chromaffin cells, which are responsible for synthesizing and secreting catecholamines.
2. Epinephrine released by the adrenal medulla can enhance oxygen delivery to muscles, increase metabolic rate, and promote glucose release for immediate energy.
3. Norepinephrine primarily acts on blood vessels to cause vasoconstriction, which helps increase blood pressure during stressful situations.
4. The adrenal medulla functions as part of the sympathetic nervous system, which prepares the body for rapid responses to stressors.
5. Dysfunction of the adrenal medulla can lead to conditions such as pheochromocytoma, a tumor that causes excessive production of catecholamines and results in severe hypertension.

Review Questions

• How does the adrenal medulla contribute to the fight-or-flight response in terms of hormone secretion?
  • The adrenal medulla contributes to the fight-or-flight response by secreting catecholamines, primarily epinephrine and norepinephrine. These hormones rapidly prepare the body for action by increasing heart rate, dilating airways, and mobilizing energy sources. This hormonal surge enables an individual to respond quickly to stressors, whether by fighting or fleeing.
• Compare and contrast the roles of epinephrine and norepinephrine in the body's stress response mediated by the adrenal medulla.
  • Epinephrine is primarily responsible for boosting energy levels and increasing metabolic activities during stress, while norepinephrine mainly focuses on regulating blood pressure through vasoconstriction. Both hormones are critical during the stress response; however, epinephrine's effects are more widespread affecting various organs, whereas norepinephrine's actions are more targeted towards maintaining blood flow and pressure. Together, they orchestrate a comprehensive physiological response to stress.
• Evaluate how dysfunctions in the adrenal medulla can impact overall health and what conditions might arise as a result.
  • Dysfunctions in the adrenal medulla can significantly impact overall health by disrupting the balance of catecholamine production. For instance, excessive secretion can lead to conditions like pheochromocytoma, which causes severe hypertension and other cardiovascular issues. On the other hand, insufficient production may result in inadequate responses to stress, leading to fatigue and diminished ability to cope with emergencies. This imbalance illustrates the vital role of the adrenal medulla in maintaining homeostasis during stressful situations.

Related terms

Epinephrine:

A hormone produced by the adrenal medulla that increases heart rate, elevates blood pressure, and boosts energy supply during stress or emergencies.

Norepinephrine: A neurotransmitter and hormone released by the adrenal medulla that helps regulate blood flow, increase heart rate, and trigger other physiological changes during the fight-or-flight response.

Fight-or-Flight Response: The physiological reaction that occurs in response to a perceived harmful event or threat, preparing the body to either confront or flee from danger.