Endocrine System Class 6 PDF

Chapter 13 Endocrine System Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Organs of the Endocrine System Copyright ©2020 F.A. Davis Company Anatom...

Chapter 13 Endocrine System Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Organs of the Endocrine System Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Endocrine System vs. Nervous System Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Endocrine System vs. Nervous System Endocrine System Nervous System ▪ Uses hormones ▪ Uses neurotransmitters ▪ Distributes hormones ▪ Secretes via the bloodstream neurotransmitters into ▪ Responds slowly a synapse ▪ Exerts long-lasting ▪ Responds quickly effects ▪ Exerts short-lived ▪ Adapts slowly to effects continuous ▪ Adapts quickly to stimulation continuous stimulation Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormones ▪ Chemical messengers with regulatory effects on cells or organs ▪ Some affect many tissues, some affect a specific tissue ▪ Travel through the blood stream to find their specific receptor ▪ Binds with the receptor to trigger changes Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormone Classifications Steroid Hormones Nonsteroid Hormones ▪ Made from cholesterol ▪ Made from proteins, amino acids ▪ Produced in adrenal cortex ▪ Can’t penetrate cell membrane, binds to receptors on cell surface Aldosterone ▪ Eg: Insulin, anti-diuretic hormone (ADH), ▪ Produced in sex glands epinephrine, norepinephrine Estrogen, testosterone ▪ Easily passes through cell membrane Copyright ©2020 F.A. Davis Company Anatomy & Physiology  The more receptors a target cell has, Hormone Binding the more sensitive it is to a hormone Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormone Regulation Negative i.e. glucose regulation Feedback i.e. temp regulation Positive i.e. oxytocin Feedback Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Pituitary Gland (Master Gland) ▪ Pituitary Gland influences majority of body’s processes ▪ Pea sized gland located under hypothalamus ▪ Controlled mainly by hypothalamus ▪ Infundibulum connects hypothalamus to pituitary ▪ Cradled in a cavity in the sphenoid bone 2 distinct glands: ▪ Anterior Pituitary Adenohypophysis ▪ Posterior Pituitary Neurohypophysis Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormones released by the Hypothalamus ▪ Gonadotropin-releasing hormone: Promotes secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) ▪ Thyrotropin-releasing hormone: Promotes secretion of thyroid-stimulating hormone (TSH) ▪ Corticotropin-releasing hormone: Promotes secretion of adrenocorticotropic hormone (ACTH) ▪ Prolactin-releasing hormone: Promotes secretion of prolactin ▪ Prolactin-inhibiting hormone: Inhibits secretion of prolactin ▪ Growth hormone-releasing hormone: Promotes secretion of growth hormone (G H) Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormones of the Hypothalamus Each hormone acts on the anterior pituitary to release, or suppress, a particular hormone For example-thyrotropin-releasing hormone stimulates the anterior pituitary to release thyrotropin [also called thyroid-stimulating hormone] In turn, this hormone stimulates the thyroid to secrete thyroid hormone [TH]. Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Anterior Pituitary Gland ▪ Glandular tissue ▪ Synthesizes and secretes a number of very important hormones all under the direction of the hypothalamus Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormones of the Anterior Pituitary Most of the hormones produced and secreted by the anterior pituitary gland are tropic. These hormones stimulate other endocrine cells to release their hormones as shown below. Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Posterior Pituitary Gland ▪ Neural tissue ▪ Stores antidiuretic hormone and oxytocin ▪ Releases hormones when stimulated by nervous system Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Pituitary Control by Negative Feedback Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Pituitary Control by CNS ▪ The brain constantly monitors conditions both inside and outside the body ▪ In turn, it triggers the release of hormones as needed ▪ For example: when it’s cold, the CNS triggers the release of TSH to promote body heat ▪ For example: After a hearty meal, it stimulates the secretion of GH to break down fats for energy and use amino acids to build tissue Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hormones of the Pituitary Gland ▪ See page 256, table at bottom of page for Hormones Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Adrenal Glands ▪ Two small glands that sit on top of the kidneys ▪ Each gland has two distinct parts that act separately: Adrenal Medulla -modified neurons and functions as part of the sympathetic nervous system Adrenal Cortex -glandular tissue and secretes steroid hormones (corticosteroids) Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Adrenal Glands Copyright ©2020 F.A. Davis Company Anatomy & Physiology Classes of Hormones Secreted by Adrenal Cortex Mineralocorticoids Glucocorticoids Sex Steroids Principal mineralocorticoid is The principal glucocorticoid is Sex steroids include a weak form of aldosterone cortisol androgen that is converted to the more potent androgen Aldosterone acts on the kidneys Glucocorticoids help the body testosterone to promote Na+ retention and K+ adapt to stress and repair excretion damaged tissue by stimulating the The testes produce much more breakdown of fat and protein, testosterone than adrenal cortex In turn, it also causes excess converting fat and protein to water retention Androgens stimulate development glucose, and releasing fatty acids of pubic and axillary hair and and glucose into the blood sustain sex drive (libido) in both They have an anti-inflammatory sexes effect The sex steroids also include small They suppress the immune system amounts of estrogen. Because this if secreted over a long term amount is small, it has little importance during reproductive Are essential for maintaining years. However, it is the only source normal blood pressure of estrogen after menopause Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Hypothalamic-Pituitary-Adrenal Axis (HPA) When a stressful event occurs, the amygdala in the brain (the area responsible for emotional processing) signals the hypothalamus to activate the sympathetic nervous system and the flight-or-flight response. The HPA axis is stimulated to help the body cope. Chronic, low-level stress keeps the HPA axis activated, and health suffers. Resulting in increased susceptibility to infection, Type 2 diabetes, obesity, cardiovascular disease, depression! Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Pineal Gland ▪ Posterior to midbrain ▪ Produces melatonin ▪ Influences sleep- wake cycles ▪ May also regulate timing of puberty Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Thymus ▪ Lies just beneath the sternum ▪ Shrinks with age ▪ Secretes thymosin and thymopoietin Role in development of immune system ▪ Part of the endocrine system because it secretes hormones ▪ Hormones make thymus part of immune system Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Thyroid ▪ Largest endocrine gland ▪ 2 large lobes connected by isthmus ▪ Wraps around trachea ▪ Can store hormones for later Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Thyroid Hormones HORMONE FUNCTION Thyroxine (T4) Principle thyroid hormone Increases energy & metabolism Triiodothyronine (T3) Increases energy & metabolism Calcitonin Regulates serum calcium levels. When blood calcium levels are high, triggers deposit of calcium to bone Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Parathyroid Glands ▪ 4 glands embedded in the posterior capsule of the thyroid ▪ Secretes Parathyroid Hormone (PTH) ▪ Parathyroid hormone: Main hormone used to maintain normal blood levels of calcium Inhibits new bone formation and stimulates the breakdown of old bone, causing calcium (and phosphate) to moveout of bone and into the blood Encourages the kidneys to reabsorb calcium Prompts the kidneys to activate vitamin D, which is important for intestinal absorption of calcium Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Calcium Homeostasis View animation on “Regulation of blood calcium levels Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Pancreas Endocrine (secrete endocrine cells from Islets of Langerhans) Exocrine (secrete digestive enzymes) Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Islets of Langerhans Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Regulation of Blood Glucose Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Regulation of Blood Glucose View animation on “Regulation of blood glucose levels” Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Gonads ▪ Maintains reproductive organs ▪ Develops secondary sex characteristics ▪ Male: Testes Secrete Testosterone ▪ Female: Ovaries Secrete Estrogen & Progesterone Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Prostaglandins ▪ Lipid molecules made by cells throughout the body ▪ Released within tissues where they are produced, effect neighboring cells ▪ Variety of roles: Pain Inflammation Fever Blood clotting Vasodilation/constriction Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Prep For Next Class 1. Read Chapter 14 "Blood" Upcoming Assignment #3: Nervous System Assignment Friday October 18 @ 4:00 PM Quiz #2: (Chapters 10, 11, 12) Thursday October 24 @ 1:00 PM Copyright ©2020 F.A. Davis Company Anatomy & Physiology  Questions Copyright ©2020 F.A. Davis Company Anatomy & Physiology