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Chapter 11 The Endocrine System * • • • • • • Endocrine vs. Exocrine Exocrine – have ducts (tubes) Endocrine - ductless Secreted directly into body fluids Regulated by NS and ES Target cells Steroid hormones – link to cell, bind to nucleus, activate genes to make specific proteins * Responding to hormones • Lock and key system – hormone fits receptor on “target” cell target cell secreting cell can’t read signal nontarget cells can’t read signal Prostaglandins • • • • • Made from organs Act locally Potent Produced just before released Produce diverse and opposite effects Control of Hormonal Secretions • Negative feedback • Hypothalamuspituitaryother endocrine glands • NSglands directly • Changes in internal environmentglands • Example: pancreas Feedback Maintaining homeostasis hormone 1 lowers body condition gland high specific body condition low raises body condition gland hormone 2 Glands Pituitary – base of brain, anterior and posterior lobes, **master gland • **Growth Hormone (GH) – stimulates size and division increases • Pituitary dwarfism and giantism • http://www.youtube.com/watch?v=Ebhf1qKVA9A • http://www.youtube.com/watch?v=WoYeU6onK3g • Prolactin (PRL) – stimulates and sustains milk production • Effect in males not understood • TSH – controls thyroid secretions • **FSH – follicle-stimulating hormone Thyroid – in neck • **Thyroxine – regulates metabolism of carbohydrates, proteins, and lipids • **Requires iodine to make • Hyper and hypo • Calcitonin – regulates blood calcium and phosphate • As calcium goes up, calcitonin increases • This triggers osteoblasts and kidneys. Goiter Why we use iodized salt Thyroid Gland (thyroxin) • Hypo Secretion (too little) – Low metabolic rate – Person is tired and often over weight • Hyper Secretion (too much) – High metabolic rate – Person is “Hyper” and often thin Parathyroids – in thyroid • **Parathyroid hormone (PTH) – increases calcium in blood • Triggers osteoclasts and kidneys • Hyper – bones soften and easily fracture, kidney stones • Hypo – tetanic contractions Pancreas – inferior to stomach • Exocrine and endocrine • Islets of Langerhans • http://bcs.whfreeman.com/thelifewire/conte nt/chp50/5002s.swf • Alpha cells – glucagon – increases blood sugar – how? • Beta cells – insulin – decreases blood sugar – how? Endocrine System Control Feedback Regulation of Blood Sugar insulin body cells take up sugar from blood pancreas high liver stores sugar reduces appetite liver blood sugar level (90mg/100ml) low triggers hunger liver releases sugar liver pancreas glucagon Diabetes: insulin deficiencyresults in an elevated blood sugar level (glucose) Diabetes Mellitus • • • • • Type I – insulin-dependent (IDDM) Immune system destroys beta cells Usually before age 20 Type II – non-insulin-dependent (NODDM) Beta cells function, but body cells lose sensitivity to insulin • Usually after age 40
