Structure of the Adrenal Medulla

The adrenal medulla is composed of chromaffin cells, which are modified postganglionic sympathetic neurons. These cells are responsible for producing and releasing two main hormones: epinephrine (adrenaline) and norepinephrine (noradrenaline).

Functions of the Adrenal Medulla

The hormones released by the adrenal medulla are part of the body's fight-or-flight response. When the body experiences stress, the adrenal medulla is activated, leading to the release of epinephrine and norepinephrine into the bloodstream. These hormones have several effects on the body, including:

Increased Heart Rate: Epinephrine and norepinephrine can increase the heart rate, leading to a rapid pulse and increased blood flow.
Dilation of Airways: These hormones cause the airways to dilate, allowing for increased oxygen intake, which is essential for the body's response to stress.
Increased Blood Sugar Levels: Epinephrine and norepinephrine can stimulate the liver to release glucose into the bloodstream, providing a quick source of energy for the body's response to stress.
Enhanced Mental Alertness: The release of these hormones can also lead to increased mental alertness and heightened awareness, helping the body to respond effectively to a stressful situation.

Regulation of the Adrenal Medulla

The release of hormones from the adrenal medulla is regulated by the sympathetic nervous system, which is responsible for the body's fight-or-flight response. When the body perceives a threat or stress, the sympathetic nervous system signals the adrenal medulla to release epinephrine and norepinephrine, initiating the physiological changes associated with the fight-or-flight response.

Study Guide

To understand the adrenal medulla, it's important to focus on the following key points:

Describe the structure of the adrenal medulla and the type of cells it contains.
Explain the functions of the hormones released by the adrenal medulla and their effects on the body during the fight-or-flight response.
Discuss the regulation of the adrenal medulla by the sympathetic nervous system and how the body's stress response is initiated.
Explore the clinical implications of adrenal medulla dysfunction, such as in conditions like pheochromocytoma.
Relate the role of the adrenal medulla to the broader concept of stress response and its impact on overall physiological functioning.