called pheochromocytomas. These tumors produce hypertension (either chronic or
acute), elevation of basal metabolism, and glucosuria.
b. Hormones of the Suprarenal Cortex (Outside Area). Approximately 28
hormones are produced by the suprarenal cortex. These hormones are produced only
in the suprarenal cortex and are essential to life. The hormones of the suprerenal
cortex are of most importance during times of stress (like trauma and disease). The
hormones produced here tend to keep body metabolism stable during such periods of
stress. The hormones reduce fluid loss, stabilize blood glucose, reduce inflammation,
and prevent shock. Animals that have had their adrenal glands removed die under
much less stress than do animals that have their adrenal glands. Occasionally, the
suprarenal cortex malfunctions. When its function is reduced, a condition called
Addison's disease results. Fatigue, muscle weakness, weight loss, low blood pressure,
gastronintestinal upset, and collapse are clinical signs of Addison's disease. When the
suprarenal cortex too actively secretes its hormones, a condition called Cushing's
disease results. Cushing's disease is characterized by the abnormal disposition of fat in
the face (called moon face) and back of the neck (called buffalo hump), obesity, edema,
hypertension, acne, abnormalities in carbohydrate metabolism (in 90 percent of
patients), and diabetes mellitus (in 20 percent of patients). The hormones produced
here can be grouped into two major categories according to their action. These two
categories are the mineralocorticoids and the glucocorticoids.
(1) Mineralocorticoids. The mineralocorticoids affect the electrolytes and
water in the body. These hormones cause a conservation of sodium (Na+) and chloride
(Cl-) by increasing the renal reabsorption of these ions. Conversely, they increase the
excretion of potassium (K+). This retention of sodium and chloride also causes a
retention of water. The principle mineralocorticoid is aldosterone. Other hormones in
this group also exhibit, to some degree, some glucocorticoid activity.
(2) Glucocorticoids. Glucocorticoids have several different metabolic
effects. They cause deposition of glycogen in the liver, gluconeogenesis (conversion of
amino acids to glucose), liberation of amino acids from proteins, mobilization of fats,
decreased utilization of glucose, and an increase in blood glucose levels.
Hydrocortisone is the principal example of a glucocorticoid. Hydrocortisone and
cortisone both have sodium-retention effects. Both hydrocortisone and cortisone have
anti-inflammatory actions and cause dissolution of lymphoid tissue. Synthetic steriods
have more effect on inflammation than do naturally occurring steroids.
6-11. THE PANCREAS
The pancreas is located behind the stomach in the curve of the duodenum. The
pancreas may be considered both an endocrine and an exocrine gland since pancreatic
juices are secreted through the common pancreatic duct. Two types of tissue make up
the pancreas. The acini secrete digestive juices into the duodenum. The Islets of
Langerhans is the endocrine tissue. The Islets of Langerhans contains two types of