PREFIX AND SUFFIX REVIEW
dys- bad, painful, difficult
epi- above, upon
eu- good, normal
exo- away from, outside, external
hyper- excessive, above
hypo- below, beneath
para- beside, near
poly- much, many
-al pertaining to
-centesis surgical puncture
-ectomy excision, surgical removal
-phagia eating, swallowing
-ptosis drooping, prolapse
The endocrine system is made up of all the major glands, which act to regulate hormones in the body (Fig. 12-1). Various endocrine organs produce and secrete these hormones to maintain homeostasis, which is defined as the state of dynamic equilibrium. In other words, the hormones act together to keep the body’s internal environment healthy. Some hormones act directly on target organs; others stimulate certain glands to secrete yet different hormones.
Hormone levels in the blood may vary according to bodily functions. Hormones usually work in pairs to maintain a healthy balance, with one acting to raise levels of other substances when needed and the other acting to lower levels when needed. For example, the hormones calcitonin and parathyroid function in an opposite, yet complementary, fashion to maintain a healthy level of calcium in the blood.
Endocrine glands are responsible for the sexual maturation of individuals from childhood to adolescence and into adulthood. Endocrine glands also play a role in the body’s ability to metabolize food and store energy.
The pituitary gland is a small, round, pea-sized structure attached to the lower surface of the hypothalamus in the brain. It is commonly called the master gland because it controls all the other glands in the body. (Even so, the pituitary is controlled by the hypothalamus.) The pituitary gland is divided into an anterior lobe and a posterior lobe. These two parts function separately to produce many different hormones (Fig. 12-2). The anterior lobe secretes the following six hormones:
Growth hormone (GH) promotes the growth of body structures, such as bones.
Thyroid-stimulating hormone (TSH) affects the growth and functioning of the thyroid gland.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are referred to as gonadotropins ...