Chapter 45: The Endocrine System

1. Chapter 45: The Endocrine System By: Grace Maxwell and Tegan Ayers

2. What is the Endocrine System? • All of an organism’s hormone-secreting cells • Major regulatory system that consists of various glands (called endocrine glands) throughout the body • These glands secrete chemicals called hormones, which regulate processes such as mood, growth and development, tissue function, metabolism, and sexual function

3. Hormones • Secreted by the endocrine glands into the extracellular fluid • Carried by the circulatory system (in blood or hemolymph) • Communicate regulatory messages within the body • Regulatory messages travel to target cells to stimulate a response

4. Hormones (cont.) • Only the specific target cells will respond to each secreted hormone • Other cells are unaffected • Create slow, but long-lasting responses • Ex. stress, dehydration, low glucose levels • Regulate long-term development • Ex. reproductive system development

5. Hormones (cont.) • Can be classified as proteins/peptides, amines, and steroids • Proteins/Peptides: water-soluble • Amines: water-soluble • Steroids: not water-soluble

6. Hormonal Control Pathways • A receptor protein detects a stimulus and sends information to a control center • Control center compares incoming signals to a set point (desired value) • The control center sends out an efferent signal (hormone or neurohormone) which directs an effector to respond • Induces specific physiological changes

7. Hormonal Control Pathways (cont.) • 3 simple hormonal control pathways: • Simple Endocrine Pathway • Simple Neurohormone Pathway • Simple Neuroendocrine Pathway • Most pathways operate on a negative feedback loop

8. Inducing a Response: Signal Transduction Pathway • Reception: • Signal molecule binds to receptor protein in or on a target cell • Each signal molecule has a specific shape that is recognized by the target cell receptors • Signal Transduction • Series of changes in cellular proteins triggered by the binding of a signal molecule to a target cell receptor protein

9. Inducing a Response: Signal Transduction Pathway (cont.) • Response • A change in the cell’s behavior such as the activation of an enzyme, change in the uptake or secretion of certain molecules, or rearrangement of the cytoskeleton

10. Review of Hormonal Signaling • Hormone receptors can be located either inside or outside the plasma membrane • Water-soluble hormones bind to receptors in the plasma membrane • Lipid-soluble hormones bind to intracellular receptors and stimulate transcription of specific genes

11. Paracrine Signaling • Similar to hormonal signaling • Passage of messages between neighboring cells by local regulators (do not use hormones) • Causes a quicker response • Common local regulators include: • Cytokines, growth factors, nitric oxide, prostaglandins • Major purpose is to help the body maintain homeostasis

12. Major Endocrine Glands in Humans

13. Hypothalamus http://neurosurgery.ucla.edu/images/Pituitary%20Program/pituitary_gland_illust_tumor.jpg • Location: • Base of the brain • Function Overview: • Receives information from nerves and initiates appropriate endocrine signals • Directs activity of the posterior pituitary gland • Regulates body temperature, breathing, sleep, hunger, thirst, excretion, sex drives, and emotions

14. Hypothalamus (Hormones) • Vasopressin: • Reduces water loss in the kidneys • Oxytocin: • Regulates birth processes and milk production • Somatostatin: • Slows secretion of growth hormone

15. Pituitary “Master” Gland • Location: • Underneath the hypothalamus, near the center of the skull • Function Overview: • Controls activity of various other glands (adrenal, thyroids, gonads)

16. Posterior Pituitary (Hormones) • Vasopressin: • Reduces water loss in the kidneys • Oxytocin: • Regulates birth processes and milk production

17. Anterior Pituitary (Hormones) • Growth Hormone: • Stimulates bone growth and metabolic functions • Prolactin (PRL) • Stimulates milk production and excretion • Follicle-Stimulating Hormone (FSH) • Stimulates production of ova/sperm • Luteinizing Hormone (LH) • Stimulates ovaries/testes

18. Anterior Pituitary (Hormones) • Thyroid-Stimulating Hormone (TSH) • Stimulates the thyroid glands • Adrenocorticotropic Hormone (ACTH) • Stimulates adrenal cortex • Melanocyte-Stimulting Hormone (MSH) • In mammals, is thought to inhibit hunger

19. Thyroid Gland • Location: • Front of the neck (below the voice box), ventral surface of the trachea • Function Overview: • Crucial role in development and maturation • Helps regulate homeostatic functions and metabolism http://www.natural-supplements-guide.com/images/thyroid_gland.gif

20. Thyroid (Hormones) • Triiodothyronine (T3)/Thyroxin (T4): • Help maintain metabolic processes • Humans mostly produce T4 , however, 1 iodine atom is subsequently removed and T3 brings about a target cell response • Calcitonin • Lowers blood calcium levels

21. Parathyroid Glands • Location: • Embedded in the surface of the thyroid • Function Overview: • Regulation of bone growth and function • Muscle/nerve function • Maintenance of calcium levels in the body http://uvahealth.com/Plone/ebsco_images/7709.jpg

22. Parathyroid (Hormones) • Parathyroid Hormone: • Raises blood levels of Ca2+ by converting Vitamin D to its active hormonal form

23. Pancreas • Location: • Intertwined with the small intestine • Function Overview: • Regulation of glucose in the blood • Digestion http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/image_article_collections/anatomy_pages/Pancreas2.jpg

24. Pancreas (Hormones) • Insulin (produced by beta cells): • Slows glycogen breakdown in the liver, lowering blood glucose levels • Glucagon: • Raises blood glucose levels

25. Adrenal Glands • Location: • One on top of each kidney • Function Overview: • Responses to stress http://www.nichd.nih.gov/health/topics/images/adrenal_gland.jpg

26. Adrenal Medulla (Hormones) • Epinephrine/Norepinephrine: • Activate fight-or-flight response to stress • Raise glucose levels, metabolic activities, heart rate, and blood pressure

27. Adrenal Cortex (Hormones) • Glucocorticoids: • Raise blood glucose levels • Mineralicorticoids: • Reabsorb Na+ and excretion of K+ in kidneys to maintain homeostasis

28. Gonads • Location: • Testes of males • Ovaries of females • Function Overview: • Stimulate growth and development • Regulate reproductive cycles and sexual behavior

29. Testes (Hormones) • Androgens: • Regulate sperm formation and male sex characteristics

30. Ovaries (Hormones) • Estrogens: • Stimulate uterine lining growth and female sex characteristics • Progesterone: • Stimulates uterine lining growth

31. Pineal Gland • Location: • Near the center of the brain • General Function: • Regulation of Circadian Rhythms http://healinghaven.typepad.com/photos/fillmores_12_power/pineal-drawing.jpg

32. Pineal (Hormones) • Melatonin: • Involved in the regulation of biological rhythms

33. Interdependence Between Body Systems Hormones help to regulate: normal blood pressure, heart rate, muscle tone, digestion, reproductive functions, etc. Therefore, the Endocrine system helps to regulate nearly all other body systems.

34. Interdependence Between Body Systems • Circulatory System • When a hormone is secreted, it is carried through the circulatory system until it reaches the target cell. • Nervous System • The hypothalamus receives information from nerves throughout the body and then produces an endocrine response. • Ex. Nerve signals send information about the change in weather which triggers the release of reproductive hormones in certain organisms.

35. Diseases/Disorders - Cretinism Causes: - Inherited condition of thyroid deficiency Symptoms: - Slowed skeletal growth, poor mental development - Protruding tongue, choking episodes, constipation and jaundice. Treatment: - Symptoms can be prevented if treated early in life with the hormone, thyroxine.

36. Graves’ Disease Causes: - The Immune system produces antibodies which mimic Thyroid-Stimulating Hormone (TSH) and causes hyperthyroidism (overproduction of thyroid hormones) - Thought to be triggered by genetics or environmental factors Symptoms: - Protruding eyes, profuse sweating, weight loss, high blood pressure, development of a goiter, change in menstrual cycle.

37. Graves’ Disease Con’t Treatment: - Stopping the thyroid’s ability to produce hormones - This can be done through taking radioactive iodine which will destroy cells in the thyroid gland. - Beta-blockers can help treat some effects of Graves’ disease

38. Diabetes Mellitus • Type I Causes: - The Immune System destroys beta cells in the pancreas which causes an insulin deficiency. - Appears during childhood. • Symptoms: - Dehydration, fatigue, blurry eyesight, weight loss, urinating more often • Treatment: - Insulin injections

39. Diabetes Mellitus Type II Causes: - Reduced responsiveness of target cells due to change in insulin receptors. - Due to lack of exercise and poor diet. Can be hereditary. Symptoms: - Dehydration, bladder, skin or kidney infections, damage to blood vessels and nerves can cause heart attack or stroke. Treatment: - Healthy diet and exercise, some require drug therapy.

40. Themes of AP Bio: Regulation • Negative Feedback Reactions • Connect response to initial stimulus • Prevents system overreaction and maintains homeostasis • Response reduces initial stimulus • Positive Feedback Reactions • Response increases initial stimulus leading to even greater response

41. Science/Technology/Society • Synthetic Hormone Treatments allow people who lack certain hormones to lead a more normal lifestyle • Ex. Growth hormone treatments have allowed hundreds of children with pituitary dwarfism to reach a normal height • Abuses: steroid treatments have been used by athletes to increase muscle size and improve performance

42. Works Cited Campbell, Neil A. and Jane B. Reece. AP Edition Biology. San Francisco: Pearson Education, 2005. Print. “Cretinism – Symptoms, Causes, Treatment of Cretinism.” Health Issues. Health-Issues.org. 2012. Web. 26 April 2012. “Type I Diabetes.” MedlinePlus. US National Library of Medicine. 2012. Web. 26 April 2012. “Type II Diabetes.” MedlinePlus. US National Library of Medicine. 2012. Web. 26 April 2012 “Understanding Graves’ Disease.” WebMD. WebMD, LLC. 2012. Web. 26 April 2012.