CHAPTER 14-THE ENDOCRINE SYSTEM
I. THE ENDOCRINE SYSTEM
A. This system is composed of glands that produce and release special chemicals known as
hormones. Hormones are special chemicals that function by regulating processes in the
human body.
B. Hormones function by effecting special target cells in the body.
C. Hormones secreted by endocrine glands are carried through the body by the blood.
D. Endocrinology-study of endocrine glands and their disorders.
II. THE PINEAL GLAND-small (about the size of an English pea) gland located in the center of the
brain.
A. This gland secretes the hormone melatonin which is associated with regulating sleep
patterns.
III. THE PITUITARY GLAND-pea-sized structure located in the brain. It is often called the Master
Gland since it regulates many bodily processes and other glands in the body.
A. 2 Divisions of the Pituitary Gland:
1. Adenohypophysis-secretes the following hormones: a. Somatotrophic Hormone (STH)-regulates the growth of the skeleton. (HGH). b. Thyrotropin Hormone (TSH)-stimulates secretions from the thyroid gland. c. Adrenocorticotrophic Hormone (ACTH)-stimulates hormonal secretions of
the adrenal glands. d. The Gonadotrophins-includes
Lutenizing Hormone (LH e. Prolactin (PRL)-a protein hormone that stimulates breast development and
milk secretion from the mammary glands.
2. Neurohypohysis-secretes the following hormones: a. Antidiuretic hormone-regulates sodium retention in the kidney. b. Oxytocin-stimulates labor and contraction.
B. Pituitary Disorders:
1. Hypersecretion of Somatotrophic Hormone-referred to as Gigantism.
2. Hyposecretion of Somatotrophic Hormone-can lead to a form of Dwarfism.
3. Hyponatremia-reduced sodium levels in the blood caused by reduced production of
antidiuretic hormone.
Follicle-Stimulating Hormone (FSH) and
). These hormones regulate the growth and
development of the sex organs and they can act to regulate the female
menstural cycle.
IV. THE THYROID GLAND-located in the neck, just below the larynx on either side of the
trachea. The thyroid gland is a bi-lobed structure. The two lobes connect at the isthmus.
A. Hormones secreted by the Thyroid Gland:
1. Thyroxine, Triiodothyronine-collectively are referred to as
Hormone (TH ).
Thyroid a. These hormones stimulate the release of enzymes that regulate
glucose oxidation. Therefore, these hormones play a critical role
in human metabolism and in regulating heat production in the body. b. These two hormones are iodine based hormones.
2. Calcitonin (CT)-functions by removing calcium from the blood and placing it in the
bones of the body. This hormone regulates calcium levels in the blood. It plays a key

role in building healthy bone tissue.
B. Disorders of the Thyroid Gland:
1. Goiter-enlarged thyroid usually related to iodine deficiencies.
2. Hyperthyroidism-overproduction of thyroid hormone. a. Graves Disease-is an example, indicators of this illness include a high
metabolic rate, abnormal weight loss and weakness. b. Exopthalamos-bulging eyes, is a symptom of hyperthyroidism.
3. Hypothyroidism-underproduction of thyroid hormone. Decreased metabolic rate,
rapid weight gain and fatigue are indicators of this illness.
V. THE PARATHYROID GLANDS-four small glands located on the posterior surface of the
thyroid gland.
A. These Glands Produce the following Hormone:
1. Parathyroid Hormone (PTH)-only hormone secreted by these glands. This
hormone has the opposite effect of calcitonin. PTH increases calcium levels
in the bloodstream during times of calcium need. It also regulates the use and
storage of calcium in the kidney.
B. Disorders of the Parathyroid Glands:
1. Hyperparathyroidism-increased PTH release. This can cause bone diseases such as osteoporosis . This can lead to kidney stones as well.
VI. THE THYMUS GLAND-located in the upper mediastinum. Recall that it decreases in size with
age. The thymus gland secretes thymosin which regulates the production of lymphocytes.
VII. THE ADRENAL GLANDS-paired, pyramid-shaped glands sitting on the kidneys.
A. Hormones secreted by the Adrenal Cortex-all are steroids:
1. Mineralocorticoids-the kidneys are the primary target organs for these hormones. a. These hormones regulate electrolyte levels in the blood by forcing their
uptake in the kidneys. b. Aldosterone-major mineralocorticoid, this hormone regulates sodium levels
in the blood.
2. Glucocorticoids-regulate the energy metabolism of most body cells and they help us
resist stressors. a. Cortisol-regulates fat breakdown in the body. b. These hormones also play a role in regulating sugar levels in the body.
3. Epinephrine and Norepinephrine (NE)-these are sometimes referred to adrenaline. a. These hormones are involved in “Fight or Flight” responses that are part of
the Autonomic Nervous System.
4. Androgens-the sex hormones, including testosterone, estrogen and progesterone.
B. Disorders of the Adrenal Glands:
1. Cushing Syndrome-hyperproduction of adrenal hormones. Also known as “Moon Pie
Face.” Symptoms include high blood pressure, fatigue.
2. Addison Disease-hyposecretion of adrenal hormones. Symptoms include low blood
pressure, reduced blood levels of sodium.
VIII. THE PANCREAS-located inferior and posterior to the stomach.
A. The pancreas is a dual organ-it has both digestive and glandular functions.
B. The Islets of Langerhans-structures in the Pancreas that function by producing hormones.
C. Hormones Secreted by the Pancreas
1. Glucagon-this hormone stimulates the liver to convert glycogen into glucose.

This hormone causes a decrease in blood sugar level by stimulating the conversion
of glucose into glycogen.
2. Insulin-stimulates body cells to take up glucose. This hormone aids in regulating
sugar levels in the blood.
D. Disorders of the Pancreas
1. Diabetes-a group of disorders in which an individual cannot regulate their blood-
sugar levels. a. There are several types of diabetes. General symptoms include: excessive
thirst, frequent urination, fatigue. See pages 476-478. b. Ketosis-condition that occurs when fats are not properly metabolized in the
body. This can also be an indicator of certain forms of diabetes.
2. Oncology-page 478.
IX. COMBINING FORMS/SUFFIXES/PREFIXES-pages 470-472.
X. DISEASES/CONDITIONS/PROCEDURES-pages 479-483.
XI. PHARMACOLOGY-page 484.