Module 2 Lesson 5 - 7

Lesson Summary

In this lesson, the following focusing question was explored:

• How do the adrenal glands and their secretions affect the body?

Located atop each kidney, each adrenal gland is really two glands. Similar to the two lobes of the pituitary gland, each adrenal cortex is composed of several layers of secretory cells, and each adrenal medulla is made of modified nerve cells. Hormones from both parts of the adrenal glands deal with stress.

Epinephrine and norepinephrine from the adrenal medulla intensify the "fight-or-flight" responses of the sympathetic nervous system. The purpose of these responses is to send more oxygen and glucose to the tissues. For example, breathing rate increases and bronchioles dilate so more oxygen can be taken to the lungs. Glucose is synthesized from glycogen. Heart rate, cardiac output, and blood pressure are increased so that the increased levels of oxygen and glucose can be delivered to the muscles.

Cortisol, from the adrenal cortex, intensifies the fight or flight responses. It increases blood glucose by converting amino acids, proteins, and fats into glucose. Cortisol also decreases the inflammatory response. Therefore, it is useful in treating allergic reactions and joint inflammations. High levels of cortisol are regulated by negative feedback on the hypothalamus and anterior pituitary and their secretions of releasing hormone and ACTH respectively. Aldosterone, another hormone from the adrenal cortex, is concerned with regulation of sodium ions and subsequent homeostasis of water balance in the circulatory system.