1. The Endocrine System Chapter 47

2. Endocrine System: The Body’s Regulatory System The nervous system is involved with high speed messages The endocrine system is slower and involves the production, release, and movement of chemical messages –Endocrine glands – ductless glands that secrete hormones into body fluids for distribution –Exocrine glands – secrete chemicals (sweat, mucus, digestive enzymes) into ducts which carry them to appropriate locations The nervous and endocrine systems are interrelated – some chemicals serve both as hormones and neurotransmitters

3. Chemical signals Bind to specific receptors within target cells or on their surface This triggers chemical events within the target cell and results in a change in its behavior Hormones coordinate metabolism, growth, development, and reproduction

4. Endocrine Glands and their Hormones Hypothalamus –In brain –Receives information from body and initiates endocrine responses Pituitary gland –Below hypothalamus –Two lobes – one releases hormones directly into bloodstream, the other stores and secretes hormones made in hypothalamus

5. Hormones… Posterior pituitary hormones –Oxytocin – involved in labor and nursing –Antidiuretic hormone – makes the kidneys increase water retention in response to dehydration Anterior pituitary hormones –Growth hormone - growth –Prolactin – mammary gland development –Follicle-stimulating hormone – spermatogenesis and ovarian follicle growth –Thyroid-stimulating hormone – stimulates the thyroid to produce its hormones

6. Hormones… Pineal gland – also in brain –Melatonin – modulates skin pigmentation and controls biorhythms Thyroid – around trachea –Thyroxine – controls metabolism Hyperthyroidism – high body temp, sweating, weight loss, irritability, high blood pressure Hypothyroidism – weight gain, lethargy, cold- intolerance Goiter (enlarged thyroid) – dietary iodine deficiency

7. Hormones… Pancreas – two antagonistic hormones –Maintains blood glucose levels close to 90 mg/ 100 mL –Insulin – secreted when blood glucose levels are high  stimulates cells to take up glucose from the blood and convert to glycogen –Glucagon – secreted when blood glucose levels fall  stimulates the liver to convert glycogen to glucose and release to bloodstream –Type I diabetes – sudden on-set; insulin- dependent –Type II diabetes – usually adults over 40; treated with diet and exercise

8. Hormones… Adrenal glands – sit on top of kidneys –Epinephrine and norepinephrine Released in response to stress (‘fight or flight’) Glucose is released as well as fatty acids Rate and stroke volume of heart increases Blood is shunted away from skin, digestive system, and kidneys, and sent to heart, brain, and skeletal muscles Breathing rate increases and bronchioles in lungs dilate

9. Hormones… Gonads (testes in males; ovaries in females) –Steroid hormones: androgens for males; estrogens for females –At puberty these stimulate the development of the secondary sex characteristics –Primary androgen is testosterone –Primary estrogen is estradiol