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The Endocrine System

Explore the similarities and differences between the nervous and endocrine systems in regulating the body. Learn about glands, hormones, feedback loops, and the role of the pituitary gland. Discover the function and effects of hormones from the pituitary, thyroid, parathyroid, thymus, and adrenal glands.

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The Endocrine System

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  1. The Endocrine System

  2. Comparing Nervous & Chemical Regulation • Nervous system: • Sends electrochemical impulses through neurons • Sends message quickly and directly to specific body part • Rapid response • Endocrine system: • Releases chemicals called hormones from ductless glands • Hormones travel through blood stream to target organ • Slower in producing an effect but effect lasts longer http://www.youtube.com/watch?v=R218fFZhq4c&safe=active

  3. Both systems: • Help to maintain balance or homeostasis

  4. Types of Glands • Exocrine glands: (glands with ducts) • Ex: bile, saliva • Endocrine glands: (“ductless glands”) • Secretions transported by bloodstream • Ex: hormones like adrenaline

  5. Hormones: • “Chemical messengers” • Released into bloodstream at one part of body and cause effect elsewhere at a particular target tissue • Target Tissue: • recognizes and responds to a specific hormone by means of receptor proteins • Effect may be to stimulate or inhibit

  6. http://www.youtube.com/watch?v=HrMi4GikWwQ&safe=active

  7. Regulation of Hormone Secretion • Rate of secretion varies with needs of body • Negative Feedback Loop • Change occurs that triggers series of events that eventually reverses the change • Helps keep constant levels • Ex: blood glucose levels

  8. Ex: Thermostat in house

  9. Feedback Loops Maintain Balance . • Temperature Control in Body • Hypothalamus (region in brain) • Maintains body temp. at set point • Temp drops • stimulates muscles to shiver generating heat • Once temp restored, stops shivering • Temp. rises • stimulates body to sweat • Once temp. restored stops sweating http://www.youtube.com/watch?v=_QbD92p_EVs&safe=active

  10. Glands of the Human Endocrine System

  11. Pineal Gland • Pea sized gland attached to base of brain • Secretes melatonin • Regulation of sleep cycle

  12. Pituitary Gland • Small gland attached to base of brain at hypothalamus • “Master gland” controls activity of many other glands

  13. Hypothalamus Controls the Pituitary • Hypothalamus • Controls release of hormones by pituitary • Receives information from nervous system to help control gland • Link between nervous and endocrine systems http://www.youtube.com/watch?v=qJj_-3dZ4ZQ&safe=active

  14. Hormones of the Pituitary Gland • TSH • thyroid stimulating hormone • Stimulates production and release of thyroxine by thyroid gland

  15. http://www.youtube.com/watch?v=Vae5CcaPN_8&safe=active

  16. Hormones of the Pituitary Gland • ACTH • adrenocorticotropic hormone • Stimulates release of hormones from cortex of adrenal glands • Ex: cortisol

  17. Hormones of the Pituitary Gland • Human Growth Hormone: • Controls growth of body, muscles, long bones and cartilage

  18. Too much: gigantism and acromegaly • Too little: dwarfism http://www.youtube.com/watch?v=AX48MPIDyYw&safe=active

  19. Hormones of the Pituitary Gland • FSH: • follicle stimulating hormone • Stimulates development of egg cells in ovaries and sperm in testes • LH: • luteinizing hormone • Causes egg release in ovary

  20. Hormones of the Pituitary Gland • ADH: • antidiuretic hormone • Controls water reabsorbtion by kidney • When released, more water is absorbed in nephron, making urine more concentrated

  21. Thyroid Gland • Secretes thyroxine • Contains iodine • Need iodine in diet for it to function properly • Secretions controlled by pituitary • Regulates metabolism • how we release energy from food

  22. Too much thyroxine • Hyperthyroidism • Eyes protrude, goiter • Too little thyroxine • Cretinism • Short stature, mental retardation

  23. Parathyroid Glands • 4 tiny oval glands embedded in back of thyroid • Secretes parathyroid hormone • Regulates calcium metabolism • Needed for proper nerve and muscle function http://www.youtube.com/watch?v=g1U_HNi7sDU&safe=active

  24. Low blood calcium – increases hormone • stored calcium released from bones into blood • High blood calcium– decreases hormone • excess calcium stored in bones

  25. Too much parathyroid hormone • Too much calcium taken from bones (brittle) • Too little parathyroid hormone • Low blood calcium causes skeletal muscles to contract violently (tetany)

  26. Thymus Gland • Located in upper chest near the heart • Helps in development of T-lymphocytes to defend against infection

  27. Adrenal Glands • On top of kidneys • Has two layers • inner medulla • outer cortex • Hormones help body deal with stress and “fight or flight response”

  28. Adrenal Medulla: • Secretes Adrenalin • In response to sudden stress (fear, anger, pain) • Increases heartbeat, blood pressure, breathing • Fight of Flight Response: • http://www.youtube.com/watch?v=4g25d7_Afmc&safe=active

  29. Adrenal Cortex: • Secretes • Cortisol • Regulates sugar metabolism

  30. Pancreas • Islets of Langerhans • small clusters of hormone secreting cells • One type secretes insulin • One type secretes glucagon • Work together to controlglucose levels in blood

  31. After digestion, glucose levels in blood increase • Insulin Secreted: lowers blood glucose • increases rate glucose moves into cells from bloodstream • promotes excess glucose to change into glycogen in liver

  32. In between meals, when blood glucose low • Glucagon Secreted: Raises blood glucose • Promotes change of glycogen stored in liver to become glucose in blood stream

  33. Diabetes • Failure to produce enough insulin • Glucose not absorbed by cells • Blood glucose levels high • Excess sugar in urine • Can go into diabetic shock, cause blindness, heart disease and even death • Test blood sugar levels regularly, get insulin shots http://www.youtube.com/watch?v=qzjjW--I-2Q&safe=active

  34. The Gonads • Secrete sex hormones • Related to development of secondary sexual characteristics • Production of egg and sperm cells

  35. Ovaries: • Secrete estrogen and progesterone • Stimulates development of female reproductive system and secondary sexual characteristics • Controls menstrual cycle

  36. Testes: • Secrete male sex hormone testosterone • Stimulates development of male reproductive system and secondary sexual characteristics

  37. Anabolic Steroids: • chemicals derived from testosterone • Help build body mass and muscle strength • Can cause liver and kidney disorders, high blood pressure, aggressive behavior and low sperm count, impotence, acne, stunted growth, heart problems • In women can cause masculinization, stop menstruation

  38. Major Focus Questions • What are hormones and how do they control the activity of specific target tissues in the body? • What are the functions of the human endocrine glands and their hormones? • How is hormone secretion regulated through negative feedback? • Compare and contrast the nervous and endocrine systems

  39. Crash Course: Endocrine System • http://www.youtube.com/watch?v=WVrlHH14q3o&safe=active • http://www.youtube.com/watch?v=YI2qYRWzSZ4&safe=active

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