Advanced Anatomy Physiology Learning Plan 1 Analysis of

Advanced Anatomy & Physiology Learning Plan 1: Analysis of the Physiology of the Endocrine System Mr. Michael Aprill Lakeshore Technical College Ch. 16: The Endocrine System (Pages 595 -624) MARIEB 8 th Edition Revised: 5/27/11 Copyright © 2010 Pearson Education, Inc.

THE ENDOCRINE SYSTEM: AN OVERVIEW • Endocrinology is the scientific study of hormones and the endocrine organs (p. 595; Fig. 16. 1). • Hormones are chemical messengers that are released to the blood and elicit target cell effects after a period of a few seconds to several days. • Hormone targets include most cells of the body. • Hormones regulate: 1. Reproduction 2. growth and development 3. Electrolyte, water, and nutrient balance 4. Cellular metabolism 5. energy balance 6. mobilization of body defenses Copyright © 2010 Pearson Education, Inc.

THE ENDOCRINE SYSTEM: AN OVERVIEW • Endocrine glands have no ducts, and release hormones through diffusion. • Endocrine glands include: • Pituitary • Thyroid • Parathyroid • Adrenal • Pineal • Several organs, such as the pancreas, gonads (testes and ovaries), and placenta, contain endocrine tissue. Copyright © 2010 Pearson Education, Inc.

THE ENDOCRINE SYSTEM: AN OVERVIEW • Autocrines are local chemical messengers that act on the same cells that secrete them. • Paracrines are local chemical messengers that act on neighboring cells, rather than the cells releasing them (p. 595). Copyright © 2010 Pearson Education, Inc.

HORMONES: Chemistry of Hormones (p. 596) • Hormones are long-distance chemical signals that are secreted by the cells to the extracellular fluid and regulate the metabolic functions of other cells. • Most hormones are amino acid based, but gonadal and adrenocortical hormones are steroids, derived from cholesterol. • Eicosanoids, which include leukotrienes and prostaglandins, derive from arachidonic acid. Copyright © 2010 Pearson Education, Inc.

HORMONES: Mechanisms of Hormone Action (pp. 596 -598; Figs. 16. 2 -16. 4) • Hormones typically: • produce changes in membrane permeability or potential • stimulate synthesis of proteins or regulatory molecules • activate or deactivate enzymes • induce secretory activity • Or stimulate mitosis. Copyright © 2010 Pearson Education, Inc.

HORMONES: Mechanisms of Hormone Action (pp. 596 -598; Figs. 16. 2 -16. 4) • Water-soluble hormones (all amino acid–based hormones EXCEPT thyroid hormone) exert their effects through an intracellular second messenger that is activated when a hormone binds to a plasma membrane receptor. (Fig. 16. 2) Copyright © 2010 Pearson Education, Inc.

HORMONES: Mechanisms of Hormone Action (pp. 596 -598; Figs. 16. 2 -16. 4) • Lipid-soluble hormones (steroids and thyroid hormone) diffuse into the cell, where they bind to intracellular receptors, migrate to the nucleus, and activate specific target sequences of DNA. Copyright © 2010 Pearson Education, Inc.

HORMONES: Mechanisms of Hormone Action (pp. 596 -598; Figs. 16. 2 -16. 4) • Second-messenger systems, activated when a hormone binds to a plasma membrane receptor, activate G proteins within the cell that alter enzyme activity. • Direct gene activation (Fig. 16. 3) occurs when a hormone binds to an intracellular receptor, which activates a specific region of DNA, causing the production of m. RNA, and initiation of protein synthesis. Copyright © 2010 Pearson Education, Inc.

HORMONES: Target Cell Specificity (p. 598) • Cells must have specific membrane or intracellular receptors to which hormones can bind. • Target cell response depends on three factors: 1. blood levels of the hormone 2. relative numbers of target cell receptors 3. affinity of the receptor for the hormone • Target cells can change their sensitivity to a hormone by changing the number of receptors. Copyright © 2010 Pearson Education, Inc.

HORMONES: Half-Life, Onset, & Duration of Hormone Activity (p. 599) • The concentration of a hormone reflects its: • Rate of release • And The rate of inactivation and removal from the body. • The half-life of a hormone is the duration of time a hormone remains in the blood, and is shortest for watersoluble hormones. • Target organ response and duration of response vary widely among hormones. Copyright © 2010 Pearson Education, Inc.

HORMONES: Interaction of Hormones at Target Cells (p. 600) • Permissiveness occurs when one hormone cannot exert its full effect without another hormone being present. • Synergism occurs when more than one hormone produces the same effects in a target cell, and their combined effects are amplified. • Antagonism occurs when one hormone opposes the action of another hormone. Copyright © 2010 Pearson Education, Inc.

HORMONES: Control of Hormone Release (p. 600; Fig. 16. 4) • Most hormone synthesis and release is regulated through negative feedback mechanisms. • Endocrine gland stimuli may be humoral, neural, or hormonal. (Fig. 16. 4—next slide) 1. Humoral: secrete hormones in response to changing blood levels of certain critical ions & nutrients. 2. Neural: Nerve fibers stimulate hormone release. 3. Hormonal: Stimulated in response to hormones. • Nervous system modulation can modify “turn-on” factors (hormonal, humoral, & neural stimuli) AND “turn-off” factors (feedback inhibition). Copyright © 2010 Pearson Education, Inc.

Figure 16. 4 Three types of endocrine gland stimuli. (a) Humoral Stimulus (b) Neural Stimulus (c) Hormonal Stimulus 1 Capillary blood contains 1 Preganglionic sympathetic 1 The hypothalamus secretes low concentration of Ca 2+, which stimulates. . . fibers stimulate adrenal medulla cells. . . hormones that. . . Hypothalamus Capillary (low Ca 2+ in blood) Parathyroid glands CNS (spinal cord) 2 …stimulate Thyroid gland (posterior view) Preganglionic sympathetic fibers Parathyroid PTH glands 2 …secretion of parathyroid hormone (PTH) by parathyroid glands* Copyright © 2010 Pearson Education, Inc. Medulla of adrenal gland the anterior pituitary gland to secrete hormones that… Thyroid gland Pituitary gland Adrenal cortex Gonad (Testis) Capillary 2 …to secrete catechola- mines (epinephrine and norepinephrine) 3 …stimulate other endocrine glands to secrete hormones

THE PITUITARY GLAND & HYPOTHALAMUS (pp. 601– 608; Figs. 16. 5– 16. 7; Table 16. 1) • The pituitary gland is situated in the sella turcica of the skull, and is connected to the brain via the infundibulum (p. 601; Fig. 16. 5). • The pituitary has two lobes: • Posterior pituitary (hypophysis) • neural in origin • Anterior pituitary (adenohypophysis) • glandular in origin (pp. 601– 603; Fig. 16. 5). Copyright © 2010 Pearson Education, Inc.

• The hypothalamo- THE PITUITARY GLAND & hypophyseal tract HYPOTHALAMUS is a neural connection between the hypothalamus and the posterior pituitary that extends through the infundibulum. (Fig. 16. 5 A) Copyright © 2010 Pearson Education, Inc.

THE PITUITARY GLAND & HYPOTHALAMUS • The hypothalamohypophyseal portal system is a vascular connection between the hypothalamus and the anterior pituitary that extends through the infundibulum. (Fig. 16. 5 B) Copyright © 2010 Pearson Education, Inc.

THE PITUITARY GLAND & HYPOTHALAMUS: Anterior Pituitary Hormones (Table 16. 1) • The anterior pituitary produces six hormones, four of which are tropic hormones that regulate secretion of other hormones, as well as a prohormone*. 1. Pro-opiomelanocortin (POMC) is a prohormone that can be split into adrenocorticotropic hormone, two natural opiates, and melanocyte-stimulating hormone (MSH). 2. Growth hormone (GH) acts on target cells in the liver, skeletal muscle, bone, and other tissues to cause the production of insulin-like growth factors (IGFs). (Fig. 16. 6) (See Next Slide) *A prohormone is a large precursor molecule that can be split enzymatically into one or more active hormones. Copyright © 2010 Pearson Education, Inc.

THE PITUITARY GLAND & HYPOTHALAMUS: Anterior Pituitary Hormones (Table 16. 1) Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc.

THE PITUITARY GLAND & HYPOTHALAMUS: Anterior Pituitary Hormones (Table 16. 1) 3. Thyroid-stimulating hormone (TSH) promotes secretion of the thyroid gland. (Fig. 16. 7) 4. Adrenocorticotropic hormone (ACTH) promotes release of corticosteroid hormones from the adrenal. 5. Gonadotropins which regulate function of the gonads. a) Follicle-stimulating hormone( FSH) b) Luteinizing hormone (LH) 6. Prolactin (PRL) stimulates the gonads and promotes milk production in humans. Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc.

THE PITUITARY GLAND & HYPOTHALAMUS: Posterior Pituitary Hormones (pp. 605 -608, Table 16. 1) • The posterior pituitary produces two neurohormones: (Table 16. 1) • Oxytocin • promotes uterine contraction and milk ejection • antidiuretic hormone (ADH) • prevents wide swings in water balance Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc.

THE THYROID GLAND (pp. 608 -612; Figs. 16. 8 -16. 10; Table 16. 2) • The thyroid gland consists of hollow follicles with follicle cells that produce thyroglobulin, and parafollicular cells that produce calcitonin (p. 608; Fig. 16. 8). Copyright © 2010 Pearson Education, Inc.

THE THYROID GLAND (pp. 608 -612; Figs. 16. 8 -16. 10; Table 16. 2) • Thyroid hormone consists of two amine hormones that act on all body cells to increase basal metabolic rate (BMR) and body heat production: (See Next Slide) • Thyroxine (T 4) • Triiodothyronine (T 3) Copyright © 2010 Pearson Education, Inc.

THE THYROID GLAND (pp. 608 -612; Figs. 16. 8 -16. 10; Table 16. 2) Copyright © 2010 Pearson Education, Inc.

THE THYROID GLAND (pp. 608 -612; Figs. 16. 8 -16. 10; Table 16. 2) • Calcitonin is a peptide hormone that lowers blood calcium by inhibiting osteoclast activity, and stimulates Ca 2+ uptake and incorporation into the bone matrix (pp. 611– 612). Copyright © 2010 Pearson Education, Inc.

THE PARATHYROID GLANDS (pp. 612 -614; Figs. 16. 11 -16. 12) • The parathyroid glands contain chief cells that secrete parathyroid hormone (PTH), or parathormone (pp. 612– 613; Figs. 16. 11– 16. 12). • Most important hormone controlling the calcium balance of the blood. • Functions include: 1. Nerve impulses 2. Muscle contraction 3. Blood Clotting Copyright © 2010 Pearson Education, Inc.

THE ADRENAL (SUPRARENAL) GLANDS (pp. 614 -620; Figs. 16. 13 -16. 16; Table 16. 3) • The adrenal glands (suprarenal glands), consist of two regions: (p. 614; Fig. 16. 13) • an inner adrenal medulla • an outer adrenal cortex Copyright © 2010 Pearson Education, Inc.

THE ADRENAL (SUPRARENAL) GLANDS: Adrenal Cortex • The adrenal cortex produces corticosteroids from three distinct regions: (pp. 614– 618; Figs. 16. 11– 16 -15; Table 16. 3). 1. zona glomerulosa 2. zona fasciculata 3. zona reticularis Copyright © 2010 Pearson Education, Inc.

THE ADRENAL (SUPRARENAL) GLANDS: Adrenal Cortex (Table 16. 3) • Mineralocorticoids, mostly aldosterone, are essential to regulation of electrolyte concentrations of extracellular fluids. • Aldosterone secretion is regulated by the renin-angiotensin mechanism, fluctuating blood concentrations of sodium and potassium ions, and secretion of ACTH. • Glucocorticoids are released in response to stress through the action of ACTH. • Gonadocorticoids are mostly weak androgens, which are converted to testosterone and estrogens in the tissue cells. • See Table 16. 3 Copyright © 2010 Pearson Education, Inc.

THE ADRENAL (SUPRARENAL) GLANDS: Adrenal Medulla (pp. 618 -620; Figs. 16. 13, 16. 16, Table 16. 3) • The adrenal medulla contains chromaffin cells that synthesize epinephrine and norepinephrine (NE) Copyright © 2010 Pearson Education, Inc.

Figure 16. 16 Stress and the adrenal gland. Short-term stress More prolonged stress Stress Nerve impulses Hypothalamus CRH (corticotropinreleasing hormone) Spinal cord Corticotroph cells of anterior pituitary Preganglionic sympathetic fibers To target in blood Adrenal medulla (secretes amino acidbased hormones) Catecholamines (epinephrine and norepinephrine) Short-term stress response 1. Increased heart rate 2. Increased blood pressure 3. Liver converts glycogen to glucose and releases glucose to blood 4. Dilation of bronchioles 5. Changes in blood flow patterns leading to decreased digestive system activity and reduced urine output 6. Increased metabolic rate Copyright © 2010 Pearson Education, Inc. Adrenal cortex (secretes steroid hormones) ACTH Mineralocorticoids Glucocorticoids Long-term stress response 1. Retention of sodium and water by kidneys 2. Increased blood volume and blood pressure 1. Proteins and fats converted to glucose or broken down for energy 2. Increased blood glucose 3. Suppression of immune system

THE PINEAL GLAND (p. 620) • The only major secretory product of the pineal gland is melatonin, a hormone derived from serotonin, in a diurnal cycle (p. 620). • The pineal gland indirectly receives input from the visual pathways in order to determine the timing of day and night (p. 620). Copyright © 2010 Pearson Education, Inc.

OTHER ENDOCRINE GLANDS & TISSUES: The Pancreas (pp. 620 -624; Figs. 16. 1716. 18; Table 16. 5) • The pancreas is a mixed gland that contains both endocrine and exocrine gland cells (pp. 620– 623; Figs. 16. 17– 16. 19; Table 16. 5). • Glucagon targets the liver where it promotes glycogenolysis, gluconeogenesis, and release of glucose to the blood. • Insulin lowers blood sugar levels by enhancing membrane transport of glucose into body cells. Copyright © 2010 Pearson Education, Inc.

OTHER ENDOCRINE GLANDS & TISSUES: The Pancreas Copyright © 2010 Pearson Education, Inc.

OTHER ENDOCRINE GLANDS & TISSUES: Gonads & Placenta (p. 623) • The ovaries produce estrogens and progesterone. • The testes produce testosterone. • The placenta secretes: • Estrogens & Progesterone (more often associated with the ovaries) • human chorionic gonadotropin (h. CG) which act on the uterus to influence pregnancy. Copyright © 2010 Pearson Education, Inc.

OTHER ENDOCRINE GLANDS & TISSUES: Hormone Secretion by Other Organs (p. 623) • The atria of the heart contain specialized cells that secrete atrial natriuretic peptide (ANP), resulting in: • decreased blood volume, blood pressure, and blood sodium concentration. • The gastrointestinal tract contains enteroendocrine cells throughout the mucosa that secrete hormones to regulate digestive functions. • The kidneys produce erythropoietin, which signals the bone marrow to produce red blood cells. • The skin produces cholecalciferol, an inactive form of vitamin D 3. • Adipose tissue produces leptin, which acts on the CNS to produce a feeling of satiety, and resistin, an insulin antagonist. • Osteoblasts in skeletal tissue secrete osteocalcin, a hormone that promotes increased insulin secretion by the pancreas and restricts fat storage by adipocytes. Copyright © 2010 Pearson Education, Inc.