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  • Chapter 10Endocrine System Endocrine glands are ductless releases hormones hormones released to target organs Exocrine glands have ducts


  • Chemistry of HormonesSteroid Hormones derived from cholesterol sex hormones adrenal cortex hormonesNonsteroid Hormones amines proteins peptides glycoproteins most hormones10-2

  • Actions of Steroid Hormones hormone crosses membranes hormone combines with receptor in nucleus synthesis of mRNA activated mRNA enters cytoplasm to direct synthesis of protein10-3

  • 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 second messenger10-4

  • Control of Hormonal Secretions primarily controlled by negative feedback mechanism10-5

  • Negative Feedback10-6

  • Major Endocrine Glands10-7

  • Pituitary GlandTwo distinct portions anterior pituitary (adenohypophysis) posterior pituitary (neurohypophysis)10-8

  • 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 hormones10-9

  • Hypothalamic Hormones10-10

  • Anterior Pituitary HormonesGrowth Hormone (GH) stimulates increase in size and rate of body cells enhances movement of amino acids through membranes promotes growth of long bones secretion stimulated by growth hormone-releasing hormone slows carbohydrate catabolism; increases blood glucose levelsProlactin (PRL) sustains milk production after birth secretion inhibited by prolactin release-inhibiting hormone10-11

  • Anterior Pituitary HormonesThyroid Stimulating Hormone (TSH) controls secretions of hormones from the thyroid gland controlled by thyrotropin-releasing hormoneAdrenocorticotropic Hormone controls secretions of some hormones of adrenal cortex controlled by corticotropin-releasing hormone10-12

  • Anterior Pituitary HormonesFollicle-Stimulating Hormone (FSH) stimulates development of egg-containing follicles in ovaries stimulates follicular cells to secrete estrogen stimulates production of sperm cells controlled by gonadotropin-releasing hormoneLuteinizing Hormone (LH) promotes secretions of sex hormones stimulates release of egg from ovary (ovulation) stimulates corpus luteum to produce progesterone controlled by gonadotropin-releasing hormone10-13

  • Posterior Pituitary HormonesAntidiuretic Hormone (ADH) causes kidneys to reduce water excretion in high concentration, raises blood pressure controlled by hypothalamus in response to changes in blood water concentration and blood volumeOxytocin (OT) stimulates uterine contractions stimulates mammary glands to release milk controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts10-14

  • Thyroid Gland10-15

  • Thyroid Gland HormonesThyroxine (T4) and Triiodothyronine (T3) increases rate of energy release from carbohydrates accelerates growth stimulates activity in the nervous system controlled by TSH Calcitonin lowers blood calcium concentrations by inhibiting release of calcium from bones increases rate at which calcium isdeposited in bones10-16

  • Thyroid Gland DisordersGeneral Hyperthyroidism high metabolic rate hyperactivity weight loss protruding eyes10-17Simple Goiter deficiency of iodine leads to deficiency of thyroid hormones gland enlarges

  • Parathyroid Glands10-18

  • Parathyroid Hormone PTH increases blood calcium levels stimulates bone resorption by osteoclasts inhibits osteoblasts stimulates kidneys to retain calcium promotes calcium absorption into intestine10-19

  • Adrenal Glands10-20

  • Adrenal Cortex HormonesAldosterone increases blood volume and pressure by promoting conservation of sodium ions and water


  • Adrenal Cortex HormonesCortisol decreases protein synthesis increases fatty acid release stimulates glucose synthesis from noncarbohydrates controlled by CRH from hypothalamus and ACTH from anterior pituitary maintain normal blood pressure anti-inflammatory effect released during long term stress10-22

  • Adrenal Medulla HormonesEpinephrine and Norepinephrine release controlled by sympathetic nervous system increases heart rate and blood pressure dilates respiratory airways promotes breakdown of glycogen increases metabolic rates10-23

  • Adrenal Cortex HormonesAdrenal androgens supplement sex hormones from the gonads may be converted to estrogen female sexual drive10-24

  • Pancreas10-25

  • Pancreatic HormonesGlucagon secreted by alpha cells of pancreatic islets stimulates liver to break down glycogen stimulates liver to convert noncarbohydrates into glucose controlled by blood glucose concentrations10-26Insulin secreted by beta cells of pancreatic islets promotes formation of glycogen from glucose enhances movement of glucose into adipose and muscle cells decreases blood glucose concentrations controlled by blood glucose concentrations

  • Other Endocrine GlandsReproductive Glands ovaries secrete estrogen and progesterone testes secrete testosterone placenta secretes estrogen, progesterone, and gonadotropins10-28

  • Other Endocrine GlandsPineal Gland secretes melatonin regulates sleep/wake cycles may control onset of puberty helps regulate female reproductive cycleThymus Gland secretes thymosins promotes development of certain lymphocytes10-28

  • Clinical ApplicationGrowth Hormone Ups and Downs Gigantism - hypersecretion of GH in children Acromegaly hypersecretion of GH in adults Dwarfism hyposecretion of GH in children10-29

  • Clinical ApplicationDiabetes Mellitus10-303 Cardinal signs polyuria polyphagia polydipsia


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