1. © 2009 The McGraw-Hill Companies, Inc. All rights reserved The Endocrine System

2. © 2009 The McGraw-Hill Companies, Inc. All rights reserved How are the endocrine and nervous systems similar?  The Endocrine System and the Nervous System are two communication systems for sending information to and from the brain  They operate differently of course 34-2

3. © 2009 The McGraw-Hill Companies, Inc. All rights reserved Introduction  The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood  Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells 34-3 target tissues Glands secrete hormones into bloodstream to

4. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-4 What are hormones?  Chemicals secreted by a cell that affect the functions of other cells  How do they affect behavior? 1 Hormones affect the growth of bodily structures (muscles and bones), affecting what you can do physically 2 They affect metabolic processes, influencing the amount of energy you have 3 Certain hormones cause the differences between boys and girls 4 Other hormones prepare the body for action during stress 5 Hormones also act in the brain to directly influence moods and drives

5. © 2009 The McGraw-Hill Companies, Inc. All rights reserved  Hormones work like neurotransmitters in that they have a special molecular structure that match the structure of a receptor 34-5

6. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-6 Hypothalamus  Controls the pituitary gland  It monitors the amount of hormones in the blood  Sends out messages to correct hormonal imbalances

7. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-7  Controlled by the hypothalamus  Located at the base of the brain  How does the pituitary gland act as the “Master Gland?”  It secretes a large number of hormones, many of which control the output of hormones by other endocrine glands – it’s the boss of other glands  Secretes the growth hormone - GH Pituitary Gland

8. © 2009 The McGraw-Hill Companies, Inc. All rights reserved Thyroid Gland  Located below the larynx (voice box)  Controls how fast your body uses energy with controls your weight…metabolism  Secretes the hormone thyroxine which controls the rate at which your body burns and uses energy 34-8

9. © 2009 The McGraw-Hill Companies, Inc. All rights reserved Thyroid Gland  What happens if there’s too much or too little thyroxine?  Hypothyroidism – too little; become tired  Hyperthyroidism – too much; overactive, lose weight and sleep 34-9

10. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-10 Extra Parathyroid Glands  Four located on the posterior surface of the thyroid gland  Secrete parathyroid hormone (PTH)  It’s responsible for bone growth and for regulating the calcium level in body

11. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-11 Adrenal Glands  Located on top of each kidney  Becomes active when angry or scared  Secretes the hormones…  Epinephrine (adrenaline)  Norepinephrine (noradrenaline)  Same effects as sympathetic nervous system

12. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-12 Adrenal Glands  epinephrine (adrenaline) increases blood pressure, breathing rate and energy level  norepinephrine (nonadrenaline) causes the heartbeat and breathing to increase; raises blood pressure  Both generate the extra energy needed to handle a difficult situation  Both can heighten emotions such as fear and anxiety  Norepinephrine sends out a chemical that will clot blood faster just in case we get cut  Glands also secrete cortical steroids – help muscles develop and cause the liver to release stored sugar when the body requires extra energy for emergencies

13. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-13 Extra Other Hormone-Producing Organs  Pineal gland Small gland Located between cerebral hemispheres Melatonin  Regulates circadian rhythms  May play a role in onset of puberty  Thymus gland Located between lungs Thymosin  Helps with immunity

14. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-14 Pancreas  Located behind the stomach  Both exocrine gland and endocrine gland  Exocrine – secretes digestive enzymes into a duct leading to the small intestine  Endocrine – secretes hormones into bloodstream  Regulates the metabolism of sugar  Secretes insulin which lowers blood sugar (used to treat Type 1 Diabetes

15. © 2009 The McGraw-Hill Companies, Inc. All rights reserved The Gonads  The Ovaries  Reproduction in females  Secrete estrogen and progesterone  Their levels vary…PMS  Responsible for female sex characteristics 34-15

16. © 2009 The McGraw-Hill Companies, Inc. All rights reserved The Gonads  Testes  Testosterone  important in physical development of male  In prenatal period, it helps decide the sex of a fetus  In adolescence, it’s important for growth of muscle and bone along with the growth of male sex characteristics 34-16

17. © 2009 The McGraw-Hill Companies, Inc. All rights reserved Hormone versus a Neurotransmitter  When a chemical is used as a neurotransmitter, it is released right beside the cell that it is to excite or inhibit  When a chemical is used as a hormone, it is released into the blood, which diffuses it throughout the body 34-17

18. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-18

19. © 2009 The McGraw-Hill Companies, Inc. All rights reserved 34-19 Back