Module 2 Lesson 5 - 4
Lesson 5 — The Adrenal Gland
The Adrenal Cortex
Read pages 452 - 453
Cortisol produced by the adrenal cortex is thought to be the most important glucocorticoid in humans. It is concerned primarily with glucose metabolism during periods of long-term stress, such as engaging in athletic competition and writing Alberta Diploma Examinations.
In response to long-term stress stimuli, the hypothalamus secretes a releasing hormone (corticotropin releasing hormone - CRH), which triggers the secretion of adrenocorticotropic hormone (ACTH) by the anterior pituitary. Then, ACTH triggers the release of cortisol.
Cortisol also has a role in helping to maintain high blood pressure. It works in conjunction with the sympathetic nervous system and the release of epinephrine and norepinephrine by the adrenal medulla. After a while, stress responses fade and normal conditions are restored in part by the parasympathetic nervous system.
Long-Term Stress
However, if stress-producing stimuli persist, the body may be subjected to an excessively high metabolic rate, high blood pressure, and an elevated heart rate for a prolonged period. This is particularly damaging for the circulatory system and is a contributing factor in increasing the risk of heart attacks and atherosclerosis.
Cortisol also acts to suppress inflammation, and it is sometimes used in the treatment of arthritis and allergies. Side effects such as reduction of the effectiveness of the immune system limit its usefulness.
You can further your understanding of the role of cortisol in body homeostasis by reading pages 452 to 453 of your textbook.Regulating Cortisol Release
Cortisol is secreted in response to ACTH when the anterior pituitary is stimulated by releasing hormone from the hypothalamus. Secretion is decreased by negative feedback exerted on the anterior pituitary and the hypothalamus as outlined in the general
regulatory pathway of tropic hormones in Figure 13.10 on page 441 of your textbook.
Watch This
Watch the following segments of Biologix-12 on Adrenal Cortex (6 minutes).