Chapter 45 Hormones and the Endocrine System A hormone called ecdysteroid regulates the timing of metamorphosis in this anise swallowtail butterfly.
Types of Intercellular Signaling
Pheromones Hormones Local Regulators Chemical signal from 1 individual to another individual Chemical signal from endocrine gland through blood to target cell Chemical signal from one cell to an adjacent cell Eg. ant trail; sex phermones Eg. peptide, steroid hormones Eg. cytokines, growth factors, nitric oxide (NO)
Endocrine System = Hormone-secreting cells + Tissues Endocrine glands: ductless, secrete hormones directly into body fluids Hormones: chemical signals that cause a response in target cells (receptor proteins for specific hormones) Affects 1 tissue, a few, or most tissues in body Or affect other endocrine glands (tropic hormones) Regulation by Positive & Negative Feedback
Examples of Feedback Systems Negative feedback systems: Thermoregulation Blood Ca2+ levels Blood glucose levels Positive feedback system: Oxytocin (birthing process; release of milk/suckling)
Types of Hormones Peptide Steroid Water-soluble Bind to receptors on plasma membrane & triggers signal transduction pathway Affects protein activity already present in cell Rapid response Short-lived Eg. oxytocin, insulin, epinephrine Lipid-soluble Enters cell & binds to intracellular receptors Causes change in gene expression (protein synthesis) Slower response Longer life Eg. testosterone, estrogen, progesterone
Epinephrine: one hormone many effects Liver cells break down glycogen and release glucose Blood vessels to skeletal muscles dilate Blood vessels to intestines constrict
Master Glands Hypothalamus Pituitary Gland
Hypothalamus regulation of Posterior Pituitary gland
Master Glands Hypothalamus Pituitary Gland Receives info from nerves and brain Initiates endocrine signals Hypothalamus Posterior pituitary gland: Oxytocin: contract uterine muscles, eject milk in nursing Antidiuretic Hormone (ADH): promote H2O retention by kidneys Pituitary Gland Anterior pituitary gland: Follicle-stimulating hormone (FSH): development of ovarian follicles (eggs); promote sperm production Luteinizing hormone (LH): trigger ovulation; stimulate testosterone production in testes
Insulin & Glucagon: Control blood glucose levels Know it!
Control of Blood Glucose High blood glucose Liver breaks down glycogen and releases glucose into blood Insulin released from pancreas Body cells take up glucose Liver stores glucose as glycogen Glucagon released from pancreas Blood glucose drops
Diabetes Mellitus Type I diabetes (10%):deficiency of insulin Insulin-dependent Autoimmune disorder beta cells of pancreas destroyed Type II diabetes (90%): failure of target cells to respond to insulin Non-insulin dependent Insulin produced cells don’t respond (defect in insulin receptor or response pathway) Risk factors: obesity, lack of exercise
Top Ten Hormones Gland Hormone Action Know the Gland , Hormone and action! Gland Hormone Action 1. Pineal Melatonin Circadian Rhythm
Top Ten Hormones Gland Hormone Action 2. Anterior Pituitary GH- growth hormone Cell growth 3. Posterior Pituitary ADH-antidiuretic hormone Water balance
Top Ten Hormones Gland Hormone Action 4. Thyroid T3/T4 Metabolism Calcitonin Decreases blood Calcium 6. Parathyroid PTH Increases blood calcium
Top Ten Hormones Gland Hormone Action 7. Pancreas (beta cells) Insulin Decreases blood sugar 8. Pancreas (alpha cells) Glucagon Increases blood sugar
Top Ten Hormones Gland Hormone Action Adrenal Cortex Glucocorticoids Anti-inflammatory Adrenal Medulla Epinephrine Fight or Flight