Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Chemical Signaling Within the Animal Body Chapter 27 Copyright © McGraw-Hill Companies Permission required for reproduction or display

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Outline Hormones Pituitary Gland  Posterior  Anterior Pancreas Gland Thyroid Gland Parathyroid Gland Adrenal Gland

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Hormones Hormone is a chemical signal produced in one part of the body that is stable enough to be transported in active form across the body. Three advantages to chemical signals:  Can spread to all tissues via blood.  Can persist much longer than electrical signals.  Many chemicals can act as hormones. - Different hormones can be used for different tissues.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Hormones Hormones produced by endocrine glands.  Completely enclosed in tissue.  Secreted into exocrine glands. Hormones controlled by Neuroendocrine system.  Hypothalamus is control center. - Issues commands to pituitary which sends signals to various hormone- producing glands.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Major Glands of Endocrine System

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Hormones How Hormones Work  Plasma membrane of target cell has embedded receptor proteins that match shape of potential signal hormone. Communication Path  Issuing Command  Transporting Signal  Hitting Target  Having Effect

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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Steroid Hormones Enter Cells Steroid hormones are manufactured from cholesterol.  Can pass across lipid bilayer of plasma membrane and bind to receptors within cell. - Alters gene activity and hormone’s effect. Anabolic Steroids are synthetic compounds that resemble testosterone.  Cause muscle cells to produce more protein.

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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Peptide Hormones Act at Cell Surface Binding of peptide hormone to receptor triggers change in cytoplasmic end of receptor protein.  Triggers events within cell cytoplasm through second messengers. - Single hormone molecule can result in formation of many second messengers in cytoplasm.

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Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Pituitary Gland Pituitary gland is located in bony recess of brain below hypothalamus and produces nine major hormones.  Two Glands - Posterior - regulates water conservation. - Anterior - regulates other glands.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Pituitary Gland Posterior Pituitary  Releases peptide hormone vasopressin. - Regulates kidney retention of water.  Releases oxytocin which initiates uterine contraction during childbirth and milk release in mothers. Both oxytocin and vasopressin are synthesized inside neurons of hypothalamus, transported down nerve axons, and stored in posterior pituitary.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Pituitary Gland Anterior Pituitary  Produces seven major peptide hormones: - Thyroid-stimulating hormone - Luteinizing hormone - Follicle-stimulating hormone - Adrenocorticotropic hormone - Growth hormone - Prolactin - Melanocyte-stimulating hormone

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Pituitary Gland Hypothalamus controls anterior pituitary hormones by secreting releasing and inhibiting hormones into blood capillaries at base of hypothalamus.  Capillaries drain into hypothalamo- hypophyseal portal system. Each releasing hormone delivered to anterior pituitary regulates secretion of specific hormone.  Negative Feedback Inhibition

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Hormonal Control of Anterior Pituitary Gland

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Pancreas Located behind the stomach and connected to front end of small intestine by narrow tube.  Secretes variety of digestive enzymes. Islets of Langerhaus govern glucose levels.  Insulin - Storage hormone that promotes accumulation of glycogen.  Glucagon - Secreted by alpha cells when glucose levels fall. (releases stored glucose) - Type I diabetes - Type II diabetes

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Thyroid Gland Thyroid gland produces several hormones.  Thyroxine - increases metabolic rate. - Contains iodine  Produces goiters  Triggers amphibian metamorphosis  Calcitonin - Stimulates bone uptake of calcium.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Parathyroid Glands Produce parathyroid hormone (PTH)  Essential for survival.  Regulates calcium levels in blood. - Fail-safe to ensure calcium levels never fall too low.  Calcium ions are key components in muscle contraction.  Acts on kidneys to reabsorb calcium ions from urine.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Adrenal Glands Mammals have two adrenal glands.  Each composed to two parts: - Medulla - inner core which produces adrenaline and norepinephrine.  Released in times of stress to trigger rapid deployment of body fuel. - Cortex - outer shell which produces cortisol and aldosterone.  Stimulates carbohydrate production and promotes uptake of sodium from urine.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Other Hormones Sexual Development  Ovaries and testes produce estrogen, progesterone, and testosterone. Biological Clocks  Pineal gland secretes melatonin. - Entrained to light and dark cycles.

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Other Hormones Nonendocrine Hormones  Right atrium secretes atrial natriuretic hormone which stimulates kidneys to excrete salt and water in urine. Molting and Metamorphosis  Molting hormone  Juvenile hormone

Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Review Hormones Pituitary Gland  Posterior  Anterior Pancreas Gland Thyroid Gland Parathyroid Gland Adrenal Gland

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