Structure and Function
The endocrine glands produce substances called hormones. Hormones are chemical substances secreted by a gland that stimulate activity elsewhere in the body. Hormones are very specialized. Hormones control the activity of specific target cells in many parts of the body. The endocrine glands include the pituitary, thyroid, parathyroid, adrenal, ovaries, testes, and the islets of Langerhans of the pancreas, where insulin is produced. Disorders of the endocrine system are caused by the hyperactivity (over-production) or hypoactivity (under-production) of hormones. The endocrine system is similar to the nervous system in function. The primary functions of the endocrine system are communication, control, and growth and development. Hormones integrate all of the body cells to function as a whole. Hormones stimulate cells within the body to multiply and mature. The following diagram identifies the location of most of the major endocrine glands in the body.
- Pituitary Gland The pituitary gland is considered the “master gland.” It regulates activity of other endocrine glands. The hypothalamus in the brain helps control the activity of the pituitary gland. The pituitary gland is roughly the size of a pea. The stalk of the pituitary gland connects with the brain. The pituitary gland produces several important hormones. One hormone is the growth hormone, which increases the rate of growth of all body cells by promoting the deposit of proteins in tissues and stimulating development of long bones. If there is hypoactivity of the growth hormone, there is decreased growth; if there is hyperactivity, there is increased growth. Several pituitary hormones control other gland activities. Some of the glands involved are the thyroid gland, the adrenal glands, the ovaries and the testes. Other hormones act primarily during pregnancy or delivery to assist with continuation of the human species. One hormone works with skin pigmentation and another works with the kidneys to control the amount of blood circulating in the body.
- The thyroid gland is located in the neck and surrounds the larynx. The thyroid gland is the largest of the endocrine glands and produces three hormones. Two of these hormones regulate the production of heat and energy in the body (metabolism). Hyperactivity can cause an increased basal metabolic rate, which is demonstrated by nervousness, weight loss, sleeplessness, restlessness, and increased muscular and nervous activity. Hypoactivity slows metabolism in the body, resulting in lack of energy, weight gain, poor concentration and apathy. The third hormone works to lower calcium in the blood by placing it into the bones.
- The adrenal glands have two parts: the cortex and the medulla, each producing separate hormones. The medulla produces two hormones that stimulate the body’s fight or flight mechanism. The adrenal glands work with the nervous system in response to an emergency. The adrenal gland hormones trigger a rise in blood pressure, heart rate, breathing and the release of glucose in the body. These hormones prepare the body for a sustained response to danger.
- The adrenal cortex produces three hormones commonly referred to as steroids. These hormones work in a variety of ways. One is used to prevent rejection in conditions in which the body fights itself such as during an allergic response, with organ transplantation, or with autoimmune diseases such as lupus or some types of arthritis. Another hormone is used to help maintain a balance between the body’s needed minerals and water. The third hormones are small amounts of the sex hormones. The adrenal cortex produces both female and male sex hormones so that both are available in the body.
- The pancreas is unique in that it has multiple functions. The part that serves as an endocrine gland is the islets of Langerhans. The islets of Langerhans are clusters of cells scattered throughout the pancreas. They produce two hormones: insulin and glucagon. These hormones work opposite of each other. Insulin works by increasing glucose usage as energy. Insulin causes the body to burn glucose first. If there is too much glucose, it helps the body store glucose as fat. Glucagon is antagonist to insulin. Glucagon stimulates the breakdown of stored glucose in times of need.
- The ovaries are the glands present in females that produce the primary female sex hormones, estrogen and progesterone. Estrogen is responsible for promoting secondary female sex characteristics. Estrogen also promotes maturation of ova for reproduction. Progesterone is released after ovulation and is responsible for maintaining a pregnancy.
- The testes are the glands present in males that produce the primary male sex hormone testosterone. Testosterone is responsible for growth and development of the male reproductive organs and is necessary for development and maintenance of the male secondary sex characteristics.
The reproductive system is responsible for sexual activity and continuation of the species. The chief characteristic of all living things is the ability to reproduce. The reproductive system also has a major function related to hormone secretion. The sex hormones are what give a person his or her sexuality. Puberty is the period in life at which one becomes functionally capable of reproduction, and secondary sexual characteristics appear. Menopause is the period of life in which a person stops being capable of reproduction.
The reproductive system consists of the sex glands, which produce sex cells and manufacture hormones, tubes and passageways for sex cells to travel, and accessory organs that assist sex cells to their destination. The male system consists of the testes, contained in the scrotum, and the penis. A system of tubes joins the testes with the urethra. The urethra passes through the prostate gland in order to connect to the outside. The female reproductive system includes two ovaries, two fallopian tubes, a uterus and the vagina.
Diabetes impairs the body’s ability to use glucose for energy. Insulin is the primary hormone involved with diabetes. The purpose of insulin is to carry glucose from the bloodstream into the cells for use as energy and fuel. When there is not enough insulin present, glucose does not get to the cells, and the cells “starve” because they do not receive the energy and food needed to function. In response to the “starving” cells, the body’s liver breaks down stores of a compound called glycogen into glucose. This glucose is released into the bloodstream in an attempt to “feed” the cells. The result is higher levels of glucose in the blood, and cells still do not receive the energy they need to function. The normal blood glucose reading before meals is 80-120 mg/dl.
Normally, insulin is released by the pancreas within minutes of a rise in the amount of glucose in the blood—for example, after a meal. Glucose level reaches a peak in 30 minutes and returns to baseline within three hours. Between periods of food intake, insulin in the blood remains low.
All diabetic residents must be observed closely for diabetic reactions. Diabetic coma (hyperglycemia) results from high blood glucose levels. Infection, medications, stress or high food intake may cause hyperglycemia. The onset of hyperglycemia is usually gradual. Insulin reaction (hypoglycemia or insulin shock) occurs with low blood glucose levels. Hypoglycemia can result from an overdose of insulin, low food intake, nausea and vomiting, or alcohol intake. Hypoglycemia onset is usually rapid. Report any signs of diabetic reactions immediately to the person providing direction and monitoring.
Symptoms of Diabetic Reactions Hyperglycemia:
- Shortness of breath
- Fruity odor to breath
- Dry mouth
- Dry, flushed skin
- Confusion, poor concentration
- Abdominal pain
- Kussmaul respiration – deep and labored breathing pattern
- Slow reflexes
- Slurred speech
- Pale, cool, clammy skin
- Mood swings
- Behavior changes
- Clumsy/jerky movement
- Poor concentration, confusion
- Tingling sensation around mouth
Drugs that Affect the Endocrine and Reproductive System
- Hormones are chemicals that are produced in a gland and transported through the bloodstream to stimulate activity or secretion in another part of the body. Almost all hormones can be replaced if a gland malfunctions.
- Thyroid agents act primarily to increase the metabolic rate. Side effects may include heart irregularities, hypertension, tremors, headache, nervousness, insomnia, weight loss and/or tachycardia.
- Antithyroid agents inhibit the production of thyroid hormones. Side effects may include drowsiness, headache, dizziness, hair loss and/or signs of hypothyroidism.
- Oral hypoglycemics function in a variety of ways. They are all dependent on the pancreas producing some insulin. Side effects may include hypoglycemia, allergic itching or rash, heartburn, nausea, and/or diarrhea.
- Corticosteroids include three categories of steroids. These hormones regulate glucose, fat and protein metabolism. They also control the immune and antiinflammatory responses. They play a role in fluid and electrolyte balance in the body. Corticosteroids are often used to control inflammation and allergic responses. They treat diseases that cause the body to turn on itself such as organ transplantation, lupus erythematosus and some respiratory diseases. Side effects may include ulcers, diabetes symptoms, acne, moon face and/or muscle wasting.
- Insulin acts primarily to lower blood glucose levels by helping glucose get to target tissues. There are several types of insulin, all of which currently must be injected into the body. A new, inhaled form of insulin is showing some promise and has been recently approved by the Food and Drug Administration (FDA). Side effects may include irritation and tissue destruction at the injection site, signs of hypoglycemia, and/or hyperglycemia.
- Sex hormones include estrogen, progesterone and testosterone. These hormones aid in the development and maintenance of reproductive organs and secondary sex characteristics. They may be used to treat certain cancers and osteoporosis, as well as for contraception or to maintain menopausal symptom control. Side effects may include edema, skin irritation, hair loss, sex characteristic changes, blood clots, depression and/or headache.