1 chapter 13 endocrine system endocrine glands are ductless exocrine glands have ducts

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  • Chapter 13Endocrine System Endocrine glands are ductless Exocrine glands have ducts

  • Endocrine GlandsEndocrine glands release hormones hormones travel through blood to target cellsParacrine secretions act locally affect only neighboring cellsAutocrine secretions affect only the secreting cell

  • Comparison of Nervous System and Endocrine System Neurons release neurotransmitters into a synapse, affecting postsynaptic cells Glands release hormones into the bloodstream Only target cells of hormone responds

  • Comparison of Nervous System and Endocrine System

  • Major Endocrine Glands

  • Chemistry of HormonesSteroid or Steroid-Like Hormones sex hormones adrenal cortex hormonesNonsteroid Hormones amines proteins peptides glycoproteins most hormones

  • Types of Hormones

  • Structural Formulas of Hormones

  • Actions of Steroid Hormones hormone crosses membranes hormone combines with receptor in nucleus synthesis of mRNA activated mRNA enters cytoplasm to direct synthesis of protein

  • Actions of Steroid Hormones

  • Actions of Nonsteroid Hormones adenylate cyclase activated hormone binds to receptor on cell membrane ATP converted to cAMP cAMP promotes a series of reactions leading to cellular changes

  • Actions of Nonsteroid Hormones

  • Prostaglandins paracrine substances

    act locally

    very potent in small amounts

    regulate cellular responses to hormones

    can activate or inhibit adenylate cyclase controls cAMP production alters cells response to hormones

    wide variety of functions

  • Control of Hormonal Secretions primarily controlled by negative feedback mechanism

  • Negative Feedback

  • Major Endocrine Glands

  • Pituitary GlandTwo distinct portions anterior pituitary (adenohypophysis) posterior pituitary (neurohypophysis)

  • Pituitary Gland Control Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones

    Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones

  • Hypothalamic Hormones

  • Hormones of the Pituitary Gland

  • Thyroid Gland

  • Thyroid Gland Hormones

  • Disorders of the Thyroid Gland

  • Disorders of the Thyroid GlandCretinism Infantile hypothyroidism Graves Disease Hyperthyroidism

  • Parathyroid Glands

  • Parathyroid Hormone

  • Parathyroid HormoneMechanism by which PTH promotes calcium absorption in the intestine

  • Disorders of the Parathyroid Glands

  • Adrenal Glands

  • Hormones of the Adrenal Medulla

  • Hormones of the Adrenal Cortex

  • Hormones of the Adrenal Cortex

  • Hormones of the Adrenal Cortex

  • Pancreas

  • Hormones of the Pancreatic Islets

  • Insulin and GlucagonInsulin and glucagon function together to stabilize blood glucose concentrations

  • Other Endocrine GlandsPineal Gland secretes melatonin regulates circadian rhythms

    Thymus Gland secretes thymosins promotes development of certain lymphocytes important in role of immunity

  • Other Endocrine GlandsReproductive ovaries produce estrogens and progesterone testes produce testosterone placenta produces estrogens, progesterone, and gonadotropins

  • StressTypes of Stress physical stress psychological stress

  • Responses to Stress

  • Life-Span Changes endocrine glands decrease in size

    muscular strength decreases as GH levels decrease

    ADH levels increase due to slower break down in liver and kidneys

    calcitonin levels decrease; increase risk of osteoporosis

    PTH level changes contribute to risk of osteoporosis

    insulin resistance may develop

    changes in melatonin secretion affect the body clock

    thymosin production declines increasing risk of infections

  • Clinical ApplicationGrowth Hormone Ups and Downs Gigantism - hypersecretion of GH in children Acromegaly hypersecretion of GH in adults Dwarfism hyposecretion of GH in childrenFigure shows oversecretion of GH in adulthood as changes occur in the same person at ages (a) nine, (b) sixteen, (c) thirty-three, and (4) fifty-two


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