Endocrine System

13 Endocrine System

Learning Outcomes • Describe the vital function of the endocrine system. • State the description and primary functions of the organs/structures of the endocrine system. • Identify the various hormones secreted by the endocrine glands and their hormonal function.

Learning Outcomes • Analyze, build, spell, and pronounce medical words. • Comprehend the drugs highlighted in this chapter. • Describe diagnostic and laboratory tests related to the endocrine system. • Identify and define selected abbreviations.

Multimedia Directory Slide 13 Endocrine System Animation Slide 14 Chemical Messengers Animation Slide 49 Diabetes Video Slide 50 Adolescent Diabetes Video Slide 74 Hypoglycemia Animation Slide 75 Hyperglycemia Animation Slide 93 Insulin Video Slide 98 Glucose Evaluation Video

Anatomy and Physiology Overview • The endocrine system is made up of ductless glands and the hormones they secrete.

Anatomy and Physiology Overview • Endocrine glands are the body’s main hormone producers; some other organs produce and release hormones: • Brain • Heart • Lungs • Liver

Anatomy and Physiology Overview • Endocrine glands are the body’s main hormone producers; some other organs produce and release hormones: • Skin • Thymus • Gastrointestinal mucosa • Placenta during pregnancy

Anatomy and Physiology Overview • Primary glands of the endocrine system: • Pituitary • Pineal • Thyroid • Parathyroid • Islets of Langerhans • Adrenals • Ovaries in the female • Testes in the male

Figure 13.1 Primary glands of the endocrine system.

Anatomy and Physiology Overview • Vital function of endocrine system: Production and regulation of chemical substances called hormones.

Anatomy and Physiology Overview • Hormones • Chemical transmitters released in small amounts and transported via bloodstream to a target organ or other cells. • Transfer information and instructions from one set of cells to another. • Regulate growth, development, mood, tissue function, homeostasis, metabolism, sexual function in male and female.

Insert table 13-1

Endocrine System Animation Click on the screenshot to view an animation on the endocrine system. The animation may take a moment to begin playing. Back to Directory

Chemical Messengers Animation Click on the screenshot to view an animation on the three types of chemical messengers. Back to Directory

Anatomy and Physiology Overview • Hyposecretion or hypersecretion of specific hormones that are caused by or are associated with pathological conditions. • Controlling the production of or replacing specific hormones can treat many hormonal disorders and/or conditions.

Anatomy and Physiology Overview • Hypothalamus • A collection of specialized cells located in the lower central part of the brain. • Is the primary link between the endocrine and nervous system. • Nerve cells control pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary.

Anatomy and Physiology Overview • Hypothalamus • Exerts direct nervous control over the anterior pituitary and the adrenal medulla. • Controls the secretion of hormones epinephrine and norepinephrine.

Table 13.2 Summary of the Endocrine Glands, Hormones, and Hormonal Functions

Table 13.2 (continued) Summary of the Endocrine Glands, Hormones, and Hormonal Functions

Life Span Considerations • Most of the structures and glands of the endocrine system develop during the first 3 months of pregnancy. • Endocrine system of newborn is supplemented by hormones that cross placental barrier. • Both male and female newborns may have swelling of the breasts and genitalia from maternal hormones.

Pituitary Gland (Hypophysis) • A small gray gland located at the base of the brain. • Lies or rests in a shallow depression of the sphenoid bone known as the sella turcica. • Attached by infundibulum stalk to hypothalamus.

Pituitary Gland (Hypophysis) • Divided into anterior lobe and posterior lobe. • Also called the master gland of the body because of its regulatory effects on the other endocrine glands.

Pituitary Gland (Hypophysis) • Anterior Lobe • Also called the adenohypophysis. • Secretes several hormones essential for growth and development of bones, muscles, other organs, sex glands, the thyroid gland, and the adrenal cortex.

Figure 13.2 Pituitary hormones and their target cells, tissues, and/or organs.

Pituitary Gland (Hypophysis) • Posterior Lobe • Also called the neurohypophysis. • Stores and secretes two important hormones, ADH and oxytocin, that are synthesized in the hypothalamus.

Pineal Gland • Small, pine cone-shaped gland located near the posterior end of corpus callosum. • Secretes hormones melatonin and serotonin. • Melatonin can be released at night to help regulate release of gonadotropin. • Serotonin is a neurotransmitter, vasoconstrictor, and smooth muscle stimulant and acts to inhibit gastric secretion.

Thyroid Gland • Large, bilobed gland located in neck. • Plays a vital role in metabolism and regulates body's metabolic processes.

Figure 13.3 Thyroid gland.

Thyroid Gland • Hyposecretion of T3 and T4 results in: • cretinism during infancy • myxedema during adulthood • Hashimoto’s disease

Thyroid Gland • Hypersecretion of T3 and T4 results in: • hyperthyroidism, also called thyrotoxicosis • Graves’ disease • exophthalmic goiter • toxic goiter • Basedow’s disease • Simple or endemic goiter is an enlargement of the thyroid gland caused by a deficiency of iodine in the diet.

Parathyroid Glands • Small, yellowish-brown bodies occurring as two pairs located on the dorsal surface and lower aspect of the thyroid gland. • Secrete parathyroid (PTH), or parathormone hormone.

Figure 13.4 Parathyroid glands.

Parathyroid Glands • Hyposecretion of PTH can result in hypoparathyroidism, which can result in tetany (intermittent cramp or tonic muscular contractions). • Hypersecretion of PTH can result in hyperparathyroidism, which may result in osteoporosis,kidney stones,and hypercalcemia.

Figure 13.5 Tetany of the hand in hypoparathyroidism.

Pancreas (Islets of Langerhans) • The islets of Langerhans are small clusters of cells located within the pancreas.

Pancreas (Islets of Langerhans) • The islets of Langerhans are composed of three major types of cells: • Alpha cells secrete glucagon, elevating blood sugar. • Beta cells secrete insulin, maintaining normal blood sugar. • Delta cells secrete somatostatin, which suppresses release of glucagon and insulin.

Figure 13.6 Pancreas — an endocrine and exocrine gland.

Figure 13.7 Islets of Langerhans.

Pancreas (Islets of Langerhans) • Hyposecretion or inadequate use of insulin may result in diabetes mellitus (DM). • Hypersecretion of insulin may result in hyperinsulinism.

Life Span Considerations • Diabetes mellitus is the most common endocrine system disorder of childhood. • Symptoms include: • Polyuria • Polydipsia • Polyphagia

Life Span Considerations • Management of DM during childhood is very difficult because diet, exercise, and medication have to be adjusted and regulated according to growth and development stages. • With aging, the number of tissue receptors decreases, thus diminishing the body’s response to hormones.

Life Span Considerations • Older adults who develop Type 2 diabetes mellitus produce sufficient insulin, but because cell receptors are modified and/or reduced, glucose does not enter the cells.

Diabetes Video Click on the screenshot to view a video on the topic of diabetes. Back to Directory

Adolescent Diabetes Video Click on the screenshot to view an video on the topic of adolescent diabetes. Back to Directory

Endocrine System