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Medical Language
Second Edition
CHAPTER
14
Endocrinology
Medical Language, Second Edition
Susan Turley
Copyright ©2011 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Endocrinology
• The medical specialty that studies the
anatomy and physiology of the endocrine
system and uses diagnostic tests, medical and
surgical procedures, and drugs to treat
endocrine system diseases.
Figure 14-1 Endocrine system
Anatomy and Physiology
• The endocrine system includes:
– Hypothalamus
– Pituitary gland
– Pineal gland
– Thyroid gland
– Parathyroid glands
Anatomy and Physiology
• The endocrine system includes:
– Thymus
– Pancreas
– Adrenal glands
– Ovaries
– Testes
Anatomy and Physiology (cont’d)
• All endocrine glands are alike in these ways:
– They secrete substances known as hormones.
– They secrete their hormones directly into the
blood and not through ducts.
– Their hormones regulate specific body functions.
Anatomy and Physiology (cont’d)
• One of the functions of the endocrine system
is to keep the body in homeostasis by
regulating body fluids, electrolytes, glucose,
cellular metabolism, growth, and the wakesleep cycle.
Anatomy and Physiology (cont’d)
• Some endocrine glands do “double duty” as
part of another body system, such as the
nervous system (hypothalamus and posterior
pituitary gland), immune system (thymus), the
digestive system (pancreas), or the genital and
reproductive system (ovaries, testes).
Anatomy of the Endocrine System
• Hypothalamus
– Located in the brain just below the thalamus
– Functions as part of both the nervous system and
the endocrine system
– Secretes substances that stimulate or inhibit the
secretion of hormones from the anterior pituitary
gland
– Produces hormones ADH and oxytocin
Figure 14-2 Endocrine glands in the brain
Anatomy of the Endocrine System
(cont’d)
• Pituitary Gland
– Located in the brain at the end of the stalk from
the hypothalamus
– Known as the master gland of the body
– Contains two different glands that function
independently of each other: the anterior
pituitary gland and the posterior pituitary gland
Anatomy of the Endocrine System
(cont’d)
• The anterior pituitary gland secretes seven
hormones:
– Thyroid-stimulating hormone (TSH)
– Follicle-stimulating hormone (FSH)
– Luteinizing hormone (LH)
– Prolactin
– Adrenocorticotropic hormone (ACTH)
– Growth hormone (GH)
– Melanocyte-stimulating hormone (MSH)
Figure 14-3 Hormones of the anterior and posterior pituitary gland
Anatomy of the Endocrine System
(cont’d)
• The posterior pituitary gland secretes two
hormones that are produced in the
hypothalamus.
– Antidiuretic hormone (ADH)
– Oxytocin
Anatomy of the Endocrine System
(cont’d)
• Pineal Gland
– Located between the two lobes of the thalamus
– Secretes the hormone melatonin
– Maintains the body’s internal clock and regulates
the onset and duration of sleep
Anatomy of the Endocrine System
(cont’d)
• Thyroid Gland
– An irregularly shaped gland that has two lobes
connected by a thin bridge of tissue (the isthmus)
– Located in the neck on either side of the trachea
and across its anterior surface
Anatomy of the Endocrine System
(cont’d)
• The thyroid gland secretes three hormones:
– T3 or triiodothyronine
– T4 or thyroxine
– Calcitonin
• When the thyroid gland is functioning
properly, this steady state is known as
euthyroidism.
Figure 14-4 Thyroid gland and parathyroid glands
Anatomy of the Endocrine System
(cont’d)
• Parathyroid Glands
– Four tiny glands
– Located on the posterior surface of the thyroid
gland, two on each lobe
– Secrete parathyroid hormone, which regulates the
amount of calcium in the blood
Anatomy of the Endocrine System
(cont’d)
• Thymus Gland
– A pink gland with two lobes located in the thoracic
cavity posterior to the sternum
– Large during childhood and puberty but shrinks
during adulthood
– Functions as part of both the body’s immune
response and the endocrine system
– Secretes thymosin
Anatomy of the Endocrine System
(cont’d)
• Pancreas
– A yellow, elongated, triangular gland located
posterior to the stomach
– Functions as part of both the digestive system and
the endocrine system
– Secretes the hormones glucagon, insulin, and
somatostatin from a group of cells known as the
islets of Langerhans
Figure 14-5 Pancreas
Anatomy of the Endocrine System
(cont’d)
• Adrenal Glands
– Contains two different glands draped over the
superior end of each kidney.
– Each gland has an outer layer (cortex) and an
inner layer (medulla).
– Each layer functions independently of the other
and secretes its own hormones.
Figure 14-6 Adrenal gland
Anatomy of the Endocrine System
(cont’d)
• Adrenal Cortex
– Secretes three groups of hormones:
• Mineralocorticoids―Aldosterone
• Glucocorticoids―Cortisol
• Androgens―Male sex hormones (in the blood, some of
the androgens are changed to estrogens, female sex
hormones)
Anatomy of the Endocrine System
(cont’d)
• Adrenal Medulla
– Secretes the hormones epinephrine and
norepinephrine into the blood when the gland is
stimulated by a nerve impulse
Anatomy of the Endocrine System
(cont’d)
• Ovaries
– Small, egg-shaped glands located in the pelvic
cavity
– Function as part of both the female reproductive
system and the endocrine system
Anatomy of the Endocrine System
(cont’d)
• Ovaries
– Follicles of the ovary secrete estradiol, the most
abundant and most biologically active female
hormone
– The corpus luteum (ruptured ovarian follicle)
secretes estradiol and progesterone.
– Cells around the follicle secrete testosterone
Anatomy of the Endocrine System
(cont’d)
• Testes
– Egg-shaped glands located outside the body in the
scrotum
– Function as part of both the male genitourinary
system and the endocrine system
– Seminiferous tubules produce spermatozoa
– Secrete testosterone, the most abundant and
biologically active of all the androgens
Anatomy of the Endocrine System
(cont’d)
• Physiology of Hormone Response and
Feedback
– The endocrine system uses hormones as chemical
messengers.
– Some neurotransmitters (epinephrine and
norepinephrine) are also hormones because they
are secreted by a gland and travel in the blood.
– Hormones target specific glands or organs with
receptors to which they can bind.
Anatomy of the Endocrine System
(cont’d)
• Synergism − When two hormones work in
conjunction with one another to accomplish
an enhanced effect.
• Antagonism − When two hormones exert an
opposite effect.
• The endocrine system maintains body
homeostasis through the use of hormones
and a negative feedback mechanism.
Figure 14-7 Effects of hormones
Diseases and Conditions
• Anterior Pituitary Gland: All Hormones
– Hyperpituitarism
– Hypopituitarism
– Dwarfism
Diseases and Conditions (cont’d)
• Anterior Pituitary Gland: Prolactin
– Galactorrhea
– Failure of lactation
Diseases and Conditions (cont’d)
• Anterior Pituitary Gland: Growth Hormone
– Gigantism
– Acromegaly
– Dwarfism
Figure 14-8 Gigantism
CORBIS-NY
Figure 14-9 Acromegaly
NMSB/Custom Medical Stock Photo, Inc.
Diseases and Conditions (cont’d)
• Posterior Pituitary Gland: Antidiuretic
Hormone (ADH)
– Syndrome of inappropriate ADH (SIADH)
– Diabetes insipidus (DI)
Diseases and Conditions (cont’d)
• Posterior Pituitary Gland: Oxytocin
– Uterine inertia
– Postpartum hemorrhage
Diseases and Conditions (cont’d)
• Pineal Gland: Melatonin
– Seasonal affective disorder (SAD)
Diseases and Conditions (cont’d)
• Thyroid Gland: T3 and T4 Thyroid Hormones
– Hyperthyroidism
• Thyrotoxicosis
• Graves’ disease
Figure 14-10 Exophthalmos
Custom Medical Stock Photo, Inc.
Figure 14-11 Goiter
Marka/Custom Medical Stock Photo, Inc.
Figure 14-12 Physical examination of the thyroid gland
Pearson Education/PH College
Diseases and Conditions (cont’d)
• Thyroid Gland: T3 and T4 Thyroid Hormones
(cont’d)
– Goiter or thyromegaly
Diseases and Conditions (cont’d)
• Thyroid Gland: T3 and T4 Thyroid Hormones
(cont’d)
– Hyperthyroidism
– Hypothyroidism
Diseases and Conditions (cont’d)
• Thyroid Gland: T3 and T4 Thyroid Hormones
(cont’d)
– Hypothyroidism
– Thyroid carcinoma
– Thyroiditis
Diseases and Conditions (cont’d)
• Parathyroid Glands: Parathyroid Hormone
– Hyperparathyroidism
– Hypoparathyroidism
Diseases and Conditions (cont’d)
• Pancreas: Insulin
– Hyperinsulinism
– Insulin resistance syndrome
Diseases and Conditions (cont’d)
• Pancreas: Insulin (cont’d)
– Diabetes Mellitus (DM)
– Ketoacidosis
Table 14-1 Diabetes Mellitus
Diseases and Conditions (cont’d)
• Adrenal Cortex: Aldosterone
– Hyperaldosteronism
– Hypoaldosteronism
Diseases and Conditions (cont’d)
• Adrenal Cortex: Cortisol
– Cushing’s syndrome
– Addison’s disease
Figure 14-13 Cushing’s syndrome
(a) Biophoto Associates / Science Source / Photo Researchers, Inc.
Diseases and Conditions (cont’d)
• Adrenal Cortex: Androgens
– Adrenogenital syndrome
Diseases and Conditions (cont’d)
• Adrenal Medulla: Epinephrine and
Norepinephrine
– Pheochromocytoma
Diseases and Conditions (cont’d)
• Ovaries: Estradiol and Progesterone
– Precocious puberty
– Infertility
– Menopause
Diseases and Conditions (cont’d)
• Testes: Testosterone
– Precocious puberty
– Gynecomastia
– Infertility
Laboratory and Diagnostic
Procedures
• Blood Tests
– Antithyroglobulin antibodies
– Calcium
– Cortisol level
Laboratory and Diagnostic
Procedures (cont’d)
• Blood Tests (cont’d)
– Fasting blood sugar (FBS)
– FSH assay and LH assay
– Glucose self-testing
Figure 14-14 Blood glucose monitor
Pearson Education/PH College
Laboratory and Diagnostic
Procedures (cont’d)
• Blood Tests (cont’d)
– Glucose tolerance test (GTT)
– Growth hormone
Laboratory and Diagnostic
Procedures (cont’d)
• Blood Tests (cont’d)
– Hemoglobin A1c (HbA1c)
– Testosterone
– Thyroid function tests (TFTs)
Laboratory and Diagnostic
Procedures (cont’d)
• Urine Tests
– ADH stimulation test
– Estradiol
– Urine dipstick
– Vanillylmandelic acid (VMA)
Laboratory and Diagnostic
Procedures (cont’d)
• Radiology Tests
– Radioactive iodine uptake (RAIU) and thyroid scan
Figure 14-15 Thyroid scan
Custom Medical Stock Photo, Inc.
Medical and Surgical Procedures
• Medical Procedures
– ADA diet
Medical and Surgical Procedures
(cont’d)
• Surgical Procedures
– Adrenalectomy
– Fine-needle biopsy
Medical and Surgical Procedures
(cont’d)
• Surgical Procedures (cont’d)
– Parathyroidectomy
– Thymectomy
– Thyroidectomy
– Transsphenoidal hypophysectomy
Drug Categories
• These categories of drugs are used to treat
endocrine Diseases and Conditions:
– Antidiabetic drugs
– Antithyroid drugs
– Corticosteroid drugs
– Growth hormone drugs
– Insulin
– Thyroid supplement drugs
Figure 14-16 Insulin injection
Custom Medical Stock Photo, Inc.
Figure 14-17 Humulin R insulin
SIU BioMed/Custom Medical Stock Photo, Inc.
Abbreviations