Essentials of Human Anatomy & Physiology Chapter 9 PDF

Chapter 9 The Endocrine System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical...

Chapter 9 The Endocrine System Lecture Presentation by Patty Bostwick-Taylor Florence-Darlington Technical College © 2018 Pearson Education, Ltd.  The Endocrine System ▪ Second controlling system of the body ▪ Nervous system is the fast-control system ▪ Uses chemical messengers (hormones) that are released into the blood ▪ Hormones control several major processes ▪ Reproduction ▪ Growth and development ▪ Mobilization of body defenses ▪ Maintenance of much of homeostasis ▪ Regulation of metabolism © 2018 Pearson Education, Ltd.  The Endocrine System ▪ Hormones are produced by specialized cells ▪ Cells secrete hormones into extracellular fluids ▪ Blood transfers hormones to target sites ▪ These hormones regulate the activity of other cells ▪ Endocrinology is the scientific study of hormones and endocrine organs © 2018 Pearson Education, Ltd.  The Chemistry of Hormones ▪ Hormones are classified chemically as: ▪ Amino acid–based, which includes: ▪ Proteins ▪ Peptides ▪ Amines ▪ Steroids—made from cholesterol ▪ Prostaglandins—made from highly active lipids that act as local hormones © 2018 Pearson Education, Ltd.  Hormone Action ▪ Hormones affect only certain tissues or organs (target cells or target organs) ▪ Target cells must have specific protein receptors ▪ Hormone binding alters cellular activity © 2018 Pearson Education, Ltd. © 2018 Pearson Education, Ltd.  Hormone Action ▪ Hormones arouse cells or alter cellular activity ▪ Typically, one or more of the following occurs: 1. Change plasma membrane permeability or membrane potential by opening or closing ion channels 2. Activate or inactivate enzymes 3. Stimulate or inhibit cell division 4. Promote or inhibit secretion of a product 5. Turn on or turn off transcription of certain genes © 2018 Pearson Education, Ltd.  Hormone Action ▪ Hormones act by two mechanisms 1. Direct gene activation ▪ Used by steroid hormones and thyroid hormone 2. Second-messenger system ▪ Used by protein and peptide hormones © 2018 Pearson Education, Ltd.  Hormone Action ▪ Direct gene activation 1. Steroid hormones diffuse through the plasma membrane of target cells 2. Once inside the cell, the hormone enters the nucleus 3. Then, the hormone binds to a specific protein within the nucleus 4. Hormone-receptor complex binds to specific sites on the cell’s DNA 5. Certain genes are activated to transcribe messenger RNA 6. New proteins are synthesized © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 1 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein 3 Hormone-receptor complex 4 DNA mRNA 5 New protein Plasma membrane of target 6 cell (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 2 Steroid Cytoplasm Nucleus hormone 1 (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 3 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 4 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein 3 Hormone-receptor complex (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 5 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein 3 Hormone-receptor complex 4 DNA (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 6 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein 3 Hormone-receptor complex 4 DNA mRNA 5 (a) Direct gene activation © 2018 Pearson Education, Ltd. Figure 9.1a Mechanisms of hormone action. Slide 7 Steroid Cytoplasm Nucleus hormone Receptor 1 2 protein 3 Hormone-receptor complex 4 DNA mRNA 5 New protein Plasma membrane of target 6 cell (a) Direct gene activation © 2018 Pearson Education, Ltd.  Hormone Action ▪ Second-messenger system 1. Hormone (first messenger) binds to a membrane receptor 2. Activated receptor sets off a series of reactions that activates an enzyme 3. Enzyme catalyzes a reaction that produces a second-messenger molecule (such as cyclic AMP, known as cAMP) 4. Oversees additional intracellular changes to promote a specific response in the target cell © 2018 Pearson Education, Ltd. Figure 9.1b Mechanisms of hormone action. Slide 1 Cytoplasm Hormone (first messenger) Enzyme ATP 1 2 3 Second cAMP messenger 4 Receptor protein Effect on cellular function, such as glycogen Plasma breakdown membrane of target cell (b) Second-messenger system © 2018 Pearson Education, Ltd. Figure 9.1b Mechanisms of hormone action. Slide 2 Cytoplasm Hormone (first messenger) 1 Receptor protein (b) Second-messenger system © 2018 Pearson Education, Ltd. Figure 9.1b Mechanisms of hormone action. Slide 3 Cytoplasm Hormone (first messenger) Enzyme 1 2 Receptor protein (b) Second-messenger system © 2018 Pearson Education, Ltd. Figure 9.1b Mechanisms of hormone action. Slide 4 Cytoplasm Hormone (first messenger) Enzyme ATP 1 2 3 Second cAMP messenger Receptor protein (b) Second-messenger system © 2018 Pearson Education, Ltd. Figure 9.1b Mechanisms of hormone action. Slide 5 Cytoplasm Hormone (first messenger) Enzyme ATP 1 2 3 Second cAMP messenger 4 Receptor protein Effect on cellular function, such as glycogen Plasma breakdown membrane of target cell (b) Second-messenger system © 2018 Pearson Education, Ltd.  Stimuli for Control of Hormone Release ▪ Hormone levels in the blood are maintained mostly by negative feedback ▪ A stimulus or low hormone levels in the blood trigger the release of more hormone ▪ Hormone release stops once an appropriate level in the blood is reached © 2018 Pearson Education, Ltd.  Stimuli for Control of Hormone Release ▪ The stimuli that activate endocrine glands fall into three major categories 1. Hormonal 2. Humoral 3. Neural © 2018 Pearson Education, Ltd.  Stimuli for Control of Hormone Release ▪ Hormonal stimuli ▪ Most common category of stimulus ▪ Endocrine organs are activated by other hormones ▪ Example: ▪ Hormones of the hypothalamus stimulate the anterior pituitary to secrete its hormones © 2018 Pearson Education, Ltd. Figure 9.2a Endocrine gland stimuli. (a) Hormonal stimulus 1 The hypothalamus secretes hormones that… Hypothalamus 2 …stimulate the anterior Anterior pituitary pituitary gland to gland secrete hormones that… Thyroid Adrenal Gonad gland cortex (testis) 3 …stimulate other endocrine glands to secrete hormones © 2018 Pearson Education, Ltd.  Stimuli for Control of Hormone Release ▪ Humoral stimuli ▪ Changing blood levels of certain ions and nutrients stimulate hormone release ▪ Humoral indicates various body fluids, such as blood and bile ▪ Examples: ▪ Parathyroid hormone and calcitonin are produced in response to changing levels of blood calcium levels ▪ Insulin is produced in response to changing levels of blood glucose levels © 2018 Pearson Education, Ltd. Figure 9.2b Endocrine gland stimuli. (b) Humoral stimulus 1 Capillary blood contains low concentration of Ca2+, which stimulates… Capillary (low Ca2+ Thyroid gland in blood) (posterior view) Parathyroid Parathyroid glands glands PTH 2 …secretion of parathyroid hormone (PTH) by parathyroid glands © 2018 Pearson Education, Ltd.  Stimuli for Control of Hormone Release ▪ Neural stimuli ▪ Nerve fibers stimulate hormone release ▪ Most are under the control of the sympathetic nervous system ▪ Examples: ▪ Sympathetic stimulation of the adrenal medulla to release epinephrine and norepinephrine © 2018 Pearson Education, Ltd. Figure 9.2c Endocrine gland stimuli. (c) Neural stimulus Preganglionic sympathetic 1 fiber stimulates adrenal medulla cells… CNS (spinal cord) Preganglionic sympathetic fibers Medulla of adrenal gland Capillary 2 …to secrete catecholamines (epinephrine and norepinephrine) © 2018 Pearson Education, Ltd.  The Major Endocrine Organs ▪ Hypothalamus ▪ Pituitary gland ▪ Pineal gland ▪ Thyroid gland ▪ Parathyroid glands ▪ Thymus ▪ Adrenal glands ▪ Pancreas ▪ Gonads (testes and ovaries) © 2018 Pearson Education, Ltd. Figure 9.3 Location of the major endocrine organs of the body. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal glands Pancreas Ovary (female) Testis (male) © 2018 Pearson Education, Ltd.  The Major Endocrine Organs ▪ Some glands have purely endocrine functions ▪ Anterior pituitary, thyroid, adrenals, parathyroids ▪ Endocrine glands are ductless glands ▪ Hormones are released directly into blood or lymph ▪ Other glands are mixed glands, with both endocrine and exocrine functions (pancreas, gonads) © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Pituitary gland ▪ Pea-sized gland that hangs by a stalk from the hypothalamus in the brain ▪ Protected by the sella turcica of the sphenoid bone ▪ Has two functional lobes ▪ Anterior pituitary—glandular tissue ▪ Posterior pituitary—nervous tissue ▪ Often called the “master endocrine gland” © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Hypothalamus produces releasing hormones and inhibiting hormones ▪ These hormones are released into portal circulation, which connects hypothalamus to anterior pituitary ▪ Hypothalamus also makes two hormones: oxytocin and antidiuretic hormone ▪ Carried to posterior pituitary via neurosecretory cells for storage © 2018 Pearson Education, Ltd. Figure 9.4 Hormones released by the posterior pituitary and their target organs. Hypothalamic neurosecretory Optic cells chiasma Hypothalamus Axon Arterial blood supply terminals Posterior lobe Capillary bed Venous drainage Anterior lobe of the pituitary ADH Oxytocin Kidney tubules Mammary glands © 2018 Pearson Education, Ltd. Uterine muscles  Pituitary Gland and Hypothalamus ▪ Posterior pituitary ▪ Does not make the hormones it releases ▪ Stores hormones made by the hypothalamus ▪ Two hormones released ▪ Oxytocin ▪ Antidiuretic hormone (ADH) © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Posterior pituitary (continued) ▪ Oxytocin ▪ Stimulates contractions of the uterus during labor, sexual relations, and breastfeeding ▪ Causes milk ejection (let-down reflex) in a breastfeeding woman © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Posterior pituitary (continued) ▪ Antidiuretic hormone (ADH) ▪ Inhibits urine production (diuresis) by promoting water reabsorption by the kidneys ▪ Urine volume decreases, blood pressure increases ▪ In large amounts, causes constriction of arterioles, leading to increased blood pressure (the reason why ADH is known as vasopressin) ▪ Alcohol inhibits ADH secretion © 2018 Pearson Education, Ltd. Figure 9.4 Hormones released by the posterior pituitary and their target organs. Hypothalamic neurosecretory Optic cells chiasma Hypothalamus Axon Arterial blood supply terminals Posterior lobe Capillary bed Venous drainage Anterior lobe of the pituitary ADH Oxytocin Kidney tubules Mammary glands © 2018 Pearson Education, Ltd. Uterine muscles  Pituitary Gland and Hypothalamus ▪ Six anterior pituitary hormones ▪ Two hormones affect nonendocrine targets 1. Growth hormone 2. Prolactin ▪ Four are tropic hormones 1. Follicle-stimulating hormone 2. Luteinizing hormone 3. Thyrotropic hormone 4. Adrenocorticotropic hormone © 2018 Pearson Education, Ltd. Figure 9.5 Hormones of the anterior pituitary and their major target organs. Releasing hormones Hypothalamus secreted into portal circulation Anterior pituitary Posterior pituitary Hypophyseal portal system Adrenocorticotropic Growth hormone (GH) hormone (ACTH) Bones and muscles Prolactin (PRL) Follicle-stimulating Thyrotropic Adrenal cortex hormone (FSH) hormone (TH) and luteinizing Mammary hormone (LH) glands Thyroid Testes or ovaries © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ All anterior pituitary hormones: ▪ Are proteins (or peptides) ▪ Act through second-messenger systems ▪ Are regulated by hormonal stimuli ▪ Are regulated mostly by negative feedback © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Growth hormone (GH) ▪ General metabolic hormone ▪ Major effects are directed to growth of skeletal muscles and long bones ▪ Plays a role in determining final body size ▪ Causes amino acids to be built into proteins ▪ Causes fats to be broken down for a source of energy © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Prolactin (PRL) ▪ Stimulates and maintains milk production following childbirth ▪ Function in males is unknown © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Gonadotropic hormones ▪ Regulate hormonal activity of the gonads ▪ Follicle-stimulating hormone (FSH) ▪ Stimulates follicle development in ovaries ▪ Stimulates sperm development in testes ▪ Luteinizing hormone (LH) ▪ Triggers ovulation of an egg in females ▪ Stimulates testosterone production in males © 2018 Pearson Education, Ltd.  Pituitary Gland and Hypothalamus ▪ Thyrotropic hormone (TH), also called thyroid-stimulating hormone (TSH) ▪ Influences growth and activity of the thyroid gland ▪ Adrenocorticotropic hormone (ACTH) ▪ Regulates endocrine activity of the adrenal cortex © 2018 Pearson Education, Ltd.  Pineal Gland ▪ Hangs from the roof of the third ventricle of the brain ▪ Secretes melatonin ▪ Believed to trigger the body’s sleep/wake cycle ▪ Believed to coordinate the hormones of fertility in humans and to inhibit the reproductive system until maturity occurs © 2018 Pearson Education, Ltd.  Thyroid Gland ▪ Found at the base of the throat, inferior to the Adam’s apple ▪ Consists of two lobes and a connecting isthmus ▪ Follicles are hollow structures that store colloidal material ▪ Produces two hormones 1. Thyroid hormone 2. Calcitonin © 2018 Pearson Education, Ltd. Figure 9.6a The thyroid gland. Thyroid cartilage Epiglottis Common carotid artery Isthmus of thyroid gland Trachea Left subclavian artery Brachiocephalic Left lobe of artery thyroid gland Aorta (a) Gross anatomy of the thyroid gland, anterior © 2018 Pearson Education, Ltd. view  Thyroid Gland ▪ Thyroid hormone ▪ Major metabolic hormone ▪ Controls rate of oxidation of glucose to supply body heat and chemical energy ▪ Needed for tissue growth and development ▪ Composed of two active iodine-containing hormones ▪ Thyroxine (T4)—secreted by thyroid follicles ▪ Triiodothyronine (T3)—conversion of T4 at target tissues © 2018 Pearson Education, Ltd. Figure 9.6b The thyroid gland. Colloid-filled follicles Follicle cells Parafollicular cells (b) Photomicrograph of thyroid gland © 2018 Pearson Education, Ltd. follicles (380x)  Thyroid Gland ▪ Calcitonin ▪ Decreases blood calcium levels by causing calcium deposition on bone ▪ Antagonistic to parathyroid hormone ▪ Produced by parafollicular cells found between the follicles © 2018 Pearson Education, Ltd. Figure 9.6b The thyroid gland. Colloid-filled follicles Follicle cells Parafollicular cells (b) Photomicrograph of thyroid gland © 2018 Pearson Education, Ltd. follicles (380x)  Parathyroid Glands ▪ Tiny masses on the posterior of the thyroid ▪ Secrete parathyroid hormone (PTH) ▪ Most important regulator of calcium ion (Ca2+) homeostasis of the blood ▪ Stimulates osteoclasts to remove calcium from bone ▪ Hypercalcemic hormone (increases blood calcium levels) ▪ Stimulates the kidneys and intestine to absorb more calcium © 2018 Pearson Education, Ltd. Figure 9.7 Hormonal control of the level of calcium ions in the blood. Calcitonin Calcitonin stimulates calcium salt deposit in bone. Thyroid gland releases calcitonin. Stimulus Rising blood IMB E AL Ca2+ levels A NC Calcium homeostasis of blood: BALANCE BALANCE 9–11 mg/100 ml IMB Stimulus E AL Falling blood A NC Ca2+ levels Thyroid gland Osteoclasts degrade bone Parathyroid matrix and release glands Parathyroid Ca2+ into blood. glands release parathyroid hormone (PTH). PTH © 2018 Pearson Education, Ltd.  Thymus ▪ Located in the upper thorax, posterior to the sternum ▪ Largest in infants and children ▪ Decreases in size throughout adulthood ▪ Produces a hormone called thymosin ▪ Matures some types of white blood cells ▪ Important in developing the immune system © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Sit on top of the kidneys ▪ Two regions 1. Adrenal cortex—outer glandular region has three layers that produce corticosteroids ▪ Mineralocorticoids are secreted by outermost layer ▪ Glucocorticoids are secreted by middle layer ▪ Sex hormones are secreted by innermost layer 2. Adrenal medulla—inner neural tissue region © 2018 Pearson Education, Ltd. Figure 9.8 Microscopic structure of the adrenal gland. Adrenal Capsule gland Mineralocorticoid- Kidney secreting area Glucocorticoid- secreting area Cortex Adrenal gland Adrenal Medulla cortex Cortex Sex hormone- Kidney secreting area Medulla Adrenal medulla © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Hormones of the adrenal cortex ▪ Mineralocorticoids (mainly aldosterone) ▪ Produced in outer adrenal cortex ▪ Regulate mineral (salt) content in blood, particularly sodium and potassium ions ▪ Regulate water and electrolyte balance ▪ Target organ is the kidney © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Hormones of the adrenal cortex (continued) ▪ Release of aldosterone is stimulated by: ▪ Humoral factors (fewer sodium ions or too many potassium ions in the blood) ▪ Hormonal stimulation (ACTH) ▪ Renin and angiotensin II in response to a drop in blood pressure ▪ Aldosterone production is inhibited by atrial natriuretic peptide (ANP), a hormone produced by the heart when blood pressure is too high © 2018 Pearson Education, Ltd. Figure 9.9 Major mechanisms controlling aldosterone release from the adrenal cortex. Decreased Na+ or Stress increased K+ in blood Hypothalamus Decreased Corticotropin- blood volume releasing and/or blood hormone pressure Anterior pituitary Increased ACTH blood pressure Kidney or blood volume Renin Heart Indirect stimulating effect via Atrial natriuretic angiotensin peptide (ANP) Angiotensin II Direct stimulating Inhibitory effect effect Mineralocorticoid- producing part of adrenal cortex Enhanced secretion of aldosterone targets kidney tubules Increased absorption Increased blood of Na+ and water; volume and increased K+ excretion blood pressure © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Hormones of the adrenal cortex (continued) ▪ Glucocorticoids (including cortisone and cortisol) ▪ Produced by middle layer of adrenal cortex ▪ Promote normal cell metabolism ▪ Help resist long-term stressors by increasing blood glucose levels (hyperglycemic hormone) ▪ Anti-inflammatory properties ▪ Released in response to increased blood levels of ACTH © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Hormones of the adrenal cortex (continued) ▪ Sex hormones ▪ Produced in the inner layer of the adrenal cortex ▪ Small amounts are made throughout life ▪ Most of the hormones produced are androgens (male sex hormones), but some estrogens (female sex hormones) are also formed © 2018 Pearson Education, Ltd.  Adrenal Glands ▪ Adrenal medulla ▪ Produces two similar hormones (catecholamines) 1. Epinephrine (adrenaline) 2. Norepinephrine (noradrenaline) ▪ These hormones prepare the body to deal with short-term stress (“fight or flight”) by: ▪ Increasing heart rate, blood pressure, blood glucose levels ▪ Dilating small passageways of lungs © 2018 Pearson Education, Ltd. Figure 9.8 Microscopic structure of the adrenal gland. Adrenal Capsule gland Mineralocorticoid- Kidney secreting area Glucocorticoid- secreting area Cortex Adrenal gland Adrenal Medulla cortex Cortex Sex hormone- Kidney secreting area Medulla Adrenal medulla © 2018 Pearson Education, Ltd. Figure 9.10 Roles of the hypothalamus, adrenal medulla, and adrenal cortex in the stress response. Short term Stress More prolonged Hypothalamus Releasing hormones Nerve impulses Spinal cord Corticotropic cells of anterior pituitary ACTH Adrenal Preganglionic cortex Adrenal sympathetic medulla fibers Mineralocorticoids Glucocorticoids Short-term stress Long-term stress response response Catecholamines 1. Increased heart rate 1. Retention of sodium 1. Proteins and fats (epinephrine and 2. Increased blood pressure and water by kidneys converted to glucose norepinephrine) 3. Liver converts glycogen to 2. Increased blood or broken down for glucose and releases glucose volume and blood energy to blood pressure 2. Increased blood sugar 4. Dilation of bronchioles 3. Suppression of 5. Changes in blood flow immune system patterns, leading to increased alertness and decreased digestive and kidney activity © 2018 Pearson Education, Ltd. 6. Increased metabolic rate  Pancreatic Islets ▪ Pancreas ▪ Located in the abdomen, close to stomach ▪ Mixed gland, with both endocrine and exocrine functions ▪ The pancreatic islets (islets of Langerhans) produce hormones ▪ Insulin—produced by beta cells ▪ Glucagon—produced by alpha cells ▪ These hormones are antagonists that maintain blood sugar homeostasis © 2018 Pearson Education, Ltd. Figure 9.11a Pancreatic tissue. Stomach Pancreas (a) © 2018 Pearson Education, Ltd. Figure 9.11b Pancreatic tissue. Exocrine cells of pancreas Pancreatic (b) islets © 2018 Pearson Education, Ltd. Figure 9.11c Pancreatic tissue. Exocrine Alpha (α) cells of cells pancreas Capillaries Cord of beta (β) cells secreting (c insulin into capillaries © 2018 Pearson Education, Ltd.  Pancreatic Islets ▪ Insulin ▪ Released when blood glucose levels are high ▪ Increases the rate of glucose uptake and metabolism by body cells ▪ Effects are hypoglycemic ▪ Glucagon ▪ Released when blood glucose levels are low ▪ Stimulates the liver to release glucose to blood, thus increasing blood glucose levels © 2018 Pearson Education, Ltd.  BioFlix™: Homeostasis © 2018 Pearson Education, Ltd. Figure 9.12 Regulation of the blood glucose level by a negative feedback mechanism involving pancreatic hormones. Uptake of glucose from blood is enhanced in most body cells. Insulin-secreting Insulin Tissue cells cells of the pancreas activated; release Pancreas Glucose Glycogen insulin into Blood glucose the blood. falls to homeostatic Elevated blood set point; stimulus Liver takes up for insulin release sugar level glucose and stores diminishes. IMB as glycogen. ALA Stimulus NC E Blood glucose BALANCE: Normal level (e.g., after blood glucose (about 90 mg/100 ml) eating four jelly level Stimulus doughnuts) Blood glucose IMB ALA NC level (e.g., after Blood glucose rises E skipping a meal) to homeostatic Low blood sugar level set point; stimulus for glucagon release diminishes. Glucagon-releasing Glucose Glycogen Liver breaks cells of pancreas down glycogen activated; release Liver glucagon into blood. stores and Glucagon releases glucose © 2018 Pearson Education,to the blood. Ltd.  Gonads ▪ Gonads ▪ Produce sex cells ▪ Produce sex hormones © 2018 Pearson Education, Ltd.  Gonads ▪ Ovaries ▪ Female gonads located in the pelvic cavity ▪ Produce eggs ▪ Produce two groups of steroid hormones 1. Estrogens 2. Progesterone ▪ Testes ▪ Male gonads suspended outside the pelvic cavity ▪ Produce sperm ▪ Produce androgens, such as testosterone © 2018 Pearson Education, Ltd. Figure 9.3 Location of the major endocrine organs of the body. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal glands Pancreas Ovary (female) Testis (male) © 2018 Pearson Education, Ltd.  Gonads ▪ Estrogens ▪ Stimulate the development of secondary female characteristics ▪ Mature the female reproductive organs ▪ With progesterone, estrogens also: ▪ Promote breast development ▪ Regulate menstrual cycle © 2018 Pearson Education, Ltd.  Gonads ▪ Progesterone ▪ Acts with estrogen to bring about the menstrual cycle ▪ Helps in the implantation of an embryo in the uterus ▪ Helps prepare breasts for lactation © 2018 Pearson Education, Ltd.  Gonads ▪ Testes ▪ Produce several androgens ▪ Testosterone is the most important androgen ▪ Responsible for adult male secondary sex characteristics ▪ Promotes growth and maturation of male reproductive system ▪ Required for sperm cell production © 2018 Pearson Education, Ltd. Table 9.1 Major Endocrine Glands and Some of Their Hormones (1 of 4). © 2018 Pearson Education, Ltd. Table 9.1 Major Endocrine Glands and Some of Their Hormones (2 of 4). © 2018 Pearson Education, Ltd. Table 9.1 Major Endocrine Glands and Some of Their Hormones (3 of 4). © 2018 Pearson Education, Ltd. Table 9.1 Major Endocrine Glands and Some of Their Hormones (4 of 4). © 2018 Pearson Education, Ltd.  Other Hormone-Producing Tissues and Organs ▪ Other organs that are generally nonendocrine in function also secrete hormones ▪ Stomach ▪ Small intestine ▪ Kidneys ▪ Heart © 2018 Pearson Education, Ltd.  Other Hormone-Producing Tissues and Organs ▪ Placenta ▪ Produces hormones that maintain pregnancy ▪ Some hormones play a part in the delivery of the baby ▪ Produces human chorionic gonadotropin (hCG) in addition to estrogen, progesterone, and other hormones ▪ Human placental lactogen (hPL) prepares the breasts for lactation ▪ Relaxin relaxes pelvic ligaments and pubic symphysis for childbirth © 2018 Pearson Education, Ltd. Table 9.2 Hormones Produced by Organs Other Than the Major Endocrine Organs (1 of 3). © 2018 Pearson Education, Ltd. Table 9.2 Hormones Produced by Organs Other Than the Major Endocrine Organs (2 of 3). © 2018 Pearson Education, Ltd. Table 9.2 Hormones Produced by Organs Other Than the Major Endocrine Organs (3 of 3). © 2018 Pearson Education, Ltd.  Developmental Aspects of the Endocrine System ▪ In the absence of disease, efficiency of the endocrine system remains high until old age ▪ Decreasing function of female ovaries at menopause leads to such symptoms as osteoporosis, increased chance of heart disease, and possible mood changes © 2018 Pearson Education, Ltd.  Developmental Aspects of the Endocrine System ▪ Efficiency of all endocrine glands gradually decreases with aging, which leads to a generalized increase in incidence of: ▪ Diabetes mellitus ▪ Immune system depression ▪ Lower metabolic rate ▪ Cancer rates in some areas © 2018 Pearson Education, Ltd.