lisämunuaisydimen

Lisämunuaisydin, also known as the adrenal medulla, is the innermost part of the adrenal glands, which are small glands located on top of each kidney. The adrenal medulla plays a crucial role in the body's response to stress by producing and releasing catecholamines, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones are responsible for the 'fight-or-flight' response, increasing heart rate, blood pressure, blood flow to muscles, and energy availability.

Structurally, the adrenal medulla consists of chromaffin cells that originate from neural crest tissue during embryonic development. These cells are specialized neuroendocrine cells capable of synthesizing, storing, and secreting catecholamines. The secretion of these hormones is stimulated by sympathetic nervous system signals in response to stress, physical danger, or excitement.

Functionally, the adrenal medulla works in concert with the adrenal cortex, which produces corticosteroids and other hormones involved in metabolism and immune regulation. Unlike the cortex, the medulla's hormones are released directly into the bloodstream, allowing for rapid systemic effects.

Disorders related to the adrenal medulla include pheochromocytoma, a rare tumor arising from chromaffin cells that results in excessive catecholamine secretion. Symptoms may include high blood pressure, headaches, sweating, and rapid heartbeat. Proper diagnosis and treatment are essential to managing such conditions.

Overall, the adrenal medulla is vital for acute stress responses, contributing to physiological adaptations necessary for survival during stressful situations.