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The Endocrine System

The Endocrine System. Chapter 20 Section 1. Imagine that you are in a damp, dark dungeon. Somewhere near you is a deep pit with water at the bottom. Overhead swings a pendulum with a razor-sharp edge. With each swing, the pendulum lowers closer and closer to your body. .

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The Endocrine System

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  1. The Endocrine System Chapter 20 Section 1

  2. Imagine that you are in a damp, dark dungeon. Somewhere near you is a deep pit with water at the bottom. Overhead swings a pendulum with a razor-sharp edge. With each swing, the pendulum lowers closer and closer to your body.

  3. The main character in Edgar Allen Poe’s story “The Pit and the Pendulum” finds himself in that vary situation. Here is his reaction: “A fearful idea now suddenly drove the blood in torrents upon my heart… I at once started to my feet, trembling convulsively in every fibre… Perspiration burst from every pore, and stood cold, big beads upon my forehead.”

  4. Hormones and the Endocrine System • The endocrine system produces chemicals that control many of the body’s daily activities. The endocrine system also regulates long-term changes such as growth and development.

  5. Endocrine Control • The endocrine system controls the body’s response to an exciting situation such as a roller coaster ride. • Endocrine glands also regulate the changes that occur as a baby grows.

  6. Endocrine Glands • The endocrine system is made up of glands. A gland is an organ that produces or releases a chemical. • Endocrine glands produce and release their chemical products directly into the bloodstream. The blood then carries those chemicals throughout the body.

  7. Hormones • The chemical product of an endocrine gland is called a hormone. • Hormones turn on, turn off, speed up, or slow down the activities of different organs and tissues. • Hormones are carried throughout the body by the blood. Therefore, hormones can regulate activities in tissues and glands that are not close to the glands that produce them.

  8. How does the body know to release hormones? • Nerve impulses from the brain interpret information then sends an impulse to an endocrine gland. The gland in turn, releases the hormone into the bloodstream.

  9. For Example • A person sees a deadly, knife-edged pendulum. • Nerve impulses travel from the person’s eye to the brain. • Then the brain sends an impulse to an endocrine gland. Endocrine gland releases adrenaline into bloodstream. • Adrenaline immediately makes the heart rate and breathing rate increase.

  10. Hormone Action • Hormones cause a slower, but longer-lasting response. • For example: When adrenaline reaches the heart, it makes the heart beat more rapidly. The heart continues to race until the amount of adrenaline in the blood drops to a normal level.

  11. How do hormones know what organs to affect? • The hormone’s chemical structure interacts with specific target cells only. • Target cells are cells that recognize the hormone’s chemical structure. • A hormone and its target cell fit together the way a key fits into a lock. • Hormones will travel through the bloodstream until they find the particular cell type that they fit.

  12. What are the types endocrine glands? • Hypothalamus • Pituitary • Thyroid • Parathyroid • Adrenal • Thymus • Pancreas • Ovaries/Testes

  13. The Hypothalamus • The hypothalamus is a tiny part of the brain near the middle of your head and is the link between the nervous system and the endocrine system. • The hypothalamus plays an important role in maintaining homeostasis, it sends nerve impulses that control sleep, hunger, and other basic body processes. It also produces hormones that control other endocrine glands and organs.

  14. The Pituitary Gland • The pituitary gland, the size of a pea, communicates with the hypothalamus to control many body activities. • In response to nerve impulses or hormone signals from the hypothalamus, the pituitary gland releases its hormones. For example; it signals the thyroid gland to produce hormones, growth hormones to regulate growth, and directs kidneys to regulate the amount of water in the blood.

  15. The Remaining Endocrine Glands • Thyroid Gland- Controls release of energy from food molecules inside cells. • Parathyroid Glands- Regulate amount of calcium in the blood. • Thymus Gland- Help immune system develop during childhood. • Pancreas- Produces insulin and glucagon, which control the level of glucose in the blood.

  16. The Remaining Endocrine Glands • Adrenal Glands- Triggers the body’s response to emergency situations. Also affect salt and water balance in the kidneys and sugar in blood. • Ovaries- Release female sex hormones. Estrogen controls changes in a female’s body. Estrogen and progesterone trigger egg development. • Testes- Release sex hormone which controls changes in a male’s body and regulates sperm production.

  17. Negative Feedback • The endocrine system often uses negative feedback to maintain homeostasis. • Negative feedback is a process by which a system is turned off by the condition it produces. • Through negative feedback, when the amount of a particular hormone in the blood reaches a certain level, the endocrine system sends signals that stop the release of hormones.

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