Slide 1IntroductionComparison of the Endocrine and Nervous SystemsSlide 4Overview of HormonesControl of Hormone SecretionNegative Feedback LoopNegative Feedback LoopPositive Feedback LoopPositive Feedback LoopHypothalamic Control of the Endocrine SystemSlide 12Mechanisms of Hypothalamic ControlMechanisms of Hypothalamic ControlSlide 15Slide 16Pituitary GlandPituitary GlandHormones of the Anterior PituitaryThyroid GlandThyroid GlandParathyroid GlandsThyroid and Parathyroid HormonesAdrenal GlandsAdrenal GlandsAdrenal CortexAdrenal Cortex HormonesAdrenal MedullaPancreasPancreasPancreatic HormonesPineal GlandThymusOther Organs with Endocrine FunctionsClickerClickerclickerEndocrine SystemIntroductionEndocrine glands are ductless organs.They secrete their molecular products (hormones) into the bloodstream.All endocrine organs have an extensive distribution of many blood vessels.The endocrine system and the nervous system both function to communicate signals throughout the body to bring about homeostasis(stay constant).Table 20.1 lists similarities and differences between the two organ systems.Slow response time compared to nervous systemBroad range of effectsComparison of the Endocrineand Nervous SystemsNervouse-rapid recovery, quick responseEndocrin-slow recovery, slow responseOverview of HormonesEndocrine glands produce informational molecules called hormones.Hormones can only affect cells (target cells) or organs (target organs) that have receptors for a specific hormone.Cells or organs that do not possess receptors for a specific hormone do not respond to that hormone.Control of Hormone SecretionHormone secretion is regulated by a self-adjusting mechanism called a feedback loop.There are two types of feedback loops:1. Negative feedback loop2. Positive feedback loopNegative Feedback LoopIn a negative feedback loop, the stimulus produces an opposite and counteracting effect to limit or minimize the original resultIn this type of loop, the stimulus starts the process ExampleEating a meal creates an elevation in blood glucose The hormone secreted in response to elevated glucose is insulin.Insulin brings about a decrease in blood glucose.Negative Feedback LoopFigure 20.2Positive Feedback LoopOnly a few examples in the human bodyIn this type of loop, the stimulus doesn’t produce an opposite and counteracting effect like a negative feedback loopThe stimulus accelerates the processPositive Feedback LoopFigure 20.2Hypothalamic Control of the Endocrine SystemThe hypothalamus is the interface between the nervous system and the endocrine system is the master gland of the endocrine system.It controls and oversees most endocrine functions.It is located in the inferior region of the diencephalon just superior to the pituitary gland.AnteriorMechanisms of Hypothalamic Control The hypothalamus controls most endocrine activity in three ways:1. Controls release of regulatory hormones from the anterior pituitary gland2. Secretes oxytocin (OT) and antidiuretic hormone (ADH) from the posterior pituitary gland3. Controls the stimulation and secretion activities of the adrenal medullaMechanisms of Hypothalamic ControlFigure 20.3Pituitary GlandLocated just inferior to the hypothalamusDivided into anterior and posterior lobesHormones secreted from anterior pituitary gland are regulated by regulatory hormones secreted from the hypothalamus.Pituitary GlandFigure 20.4Hormones of the Anterior PituitaryThere are seven major hormones secreted from the anterior pituitary:1. Thyroid stimulating hormone (TSH)2. Prolactin (PRL)3. Adrenocorticotropin hormone (ACTH)4. Growth hormone (GH)—also called somatotropin5. Follicle stimulating hormone (FSH)6. Lutenizing hormone (LH)7. Melanocyte-stimulating hormone (MSH)Thyroid GlandThe largest gland entirely devoted to endocrine activitiesLocated just inferior to the thyroid cartilage and anterior to the tracheaButterfly shape with right and left lobes connected by a midline isthmusProduces thyroid hormone which increases cell metabolism throughout the bodyThyroid GlandFigure 20.9Parathyroid GlandsSmall glands (usually four small nodules) embedded on the posterior surface of the thyroid gland Produce parathyroid hormone which effects bone remodeling Figure 20.11Thyroid and Parathyroid HormonesAdrenal GlandsPaired glands anchored on the superior border of the two kidneys; also called suprarenal glandsEmbedded in fat and fascia to minimize movementFigure 20.13Adrenal GlandsDivided functionally into an outer adrenal cortex and an inner adrenal medullaFigure 20.13Adrenal CortexThree distinct layers of cells (from superficial to deep) that produce cortocosteriods: Zona glomerulosa—produce mineralocorticoids, the main one being aldosterone.Controls long-term blood pressure Zona fasciculata—produce glucocorticoids, the main ones being corticosterone and cortisolMobilizes fats, proteins and carbohydrates  Zona reticularis—produce the sex hormones, estrogen- and testosterone-related hormonesAdrenal Cortex HormonesAdrenal MedullaForms the inner core of the adrenal glandSecretes norepinephrine and epinephrineControls Fight-or-Flight Mechanism Figure 20.13PancreasLocated between the duodenum and spleen and posterior to the stomachElongated, spongy, nodularPancreasBoth an exocrine (ducted gland) and endocrine (ductless) glandAbout 98–99% of pancreatic cells are pancreatic acini that produce alkaline pancreatic secretions into digestive ducts (Digestive system functions)The remaining 1–2% of cells (approx. 1 million cells) are small clusters of endocrine cells called pancreatic islets (islets of Langerhans) (Endocrine system functions)The hormones of the islet cells closely regulate the level of blood glucoseSecretes glucagon (increases blood glucose levels) and insulin (counterbalances blood glucose levels)Pancreatic HormonesPineal GlandSecretes melatonin, which is involved in maintaining the 24-hour circadian cycle (helps maintain sleep rate cycle)It is located in the posterior region of the epithalamusThymusLocated just superior to the heart and just deep to the sternumLarger in infants and children than in adultsLarger when we are younger and building our immune systemFunctions in association with the lymphatic system to regulate and maintain body immunity(Main