1 / 24

Chapter 39

Chapter 39. Sections 1 & 2. The Endocrine System. Made of glands that release their products into the bloodstream. Products can deliver messages throughout the body. Hormones.

irina
Download Presentation

Chapter 39

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 39 Sections 1 & 2

  2. The Endocrine System • Made of glands that release their products into the bloodstream. • Products can deliver messages throughout the body.

  3. Hormones • Chemicals that are released in one part of the body that travel through the bloodstream and affect the activities of cells in other parts of the body. • Bind to specific sites on cells. If a cell doesn’t have the site, it doesn’t respond to the hormone. • Target Cells are the cells that have receptors to the hormone.

  4. How do hormones and nerves compare? • Hormones • Response slower (minutes to days) • Chemicals travel through bloodstream. • Nerve Impulses • Response fast (fraction of a second). • “Chain” reaction to elicit response.

  5. Glands – organs that produce and release substances (excretions) • Exocrine glands • Release secretions directly to organs that use them • Examples: sweat, tears, digestive juices • Endocrine glands • Release secretions (hormones) into bloodstream • Examples: thymus, adrenal glands, testis, ovaries, etc.

  6. Hormone Action – Read the section on how hormones work (p. 999) and fill in your lecture notes. • Steroid Hormones • Produced from cholesterol (a lipid) • Can cross cell membranes easily • Nonsteroid Hormones • Include proteins, small peptides and modified amino acids. • Generally cannot pass through the cell membrane of target cell.

  7. Prostaglandins • “Local Hormones” • Modified fatty acids that are produced by a wide range of cells (not just those in the endocrine system). • Generally affect only nearby cells and tissues (which is why they’re called “local hormones”) • Why is aspirin associated with prostoglandins?

  8. Feedback Mechanisms – Remember These? • Controlling Metabolism • Thyroxine is a hormone that controls the rate of metabolism in the body. • It’s produced by the thyroid. • When thyroxine levels are low, hypothalamus secretes TRH (thyrotropin-releasing hormone) • TRH causes pituitary to produce TSH (thyroid stimulating hormone) • TSH acts on the thyroid to get it to produce more thyroxine. hypothalamus pituitary thyroid TRH TSH Thyroxine

  9. High levels of thyroxine inhibit the secretion of TRH and TSH. • This stops the release of additional thyroxine. hypothalamus pituitary thyroid TRH TSH Thyroxine Feedback

  10. Maintaining Water BalanceMajor Points • Exercise/Sweat  Body Loses Water •  Concentration of solute in blood increases •  Hypothalmus responds • signal pituitary to release ADH (antidiuretic hormome) •  ADH goes to kidneys where water reabsorption is decreased. •  Drink water •  pituitary releases less ADH •  kidneys remove water rom blood and original concentration is restored.

  11. Complementary Hormone Action • Some hormone systems have “opposite effect” hormones – one may increase the concentration of the chemical, the other will decrease it.

  12. Calcium Ion Regulation • Calcitonin (from the thyroid) • Decreases calcium • Parathyroid hormone (PTH) from the parathyroid gland. • Increases calcium

  13. Calcium Levels Too High • Thyroid secretes calcitonin. • This signals the kidneys to reabsorb less calcium as they form urine. • Reduces amount of calcium absorbed in the intestines • Stimulates calcium deposition in the bones.

  14. Calcium Levels Too Low • PTH released by the parathyroids. • Stimulates the intestine to absorb more calcium from food (along with vitamin D). • Causes kidneys to retain more calcium. • Stimulates bone cells to release some of the calcium stored in bone tissue.

  15. §39-2 Human Endocrine Glands • They’re everywhere • Regulate a wide variety of activities

  16. Pituitary Gland • Bean-sized structure at the base of the skull. • Anterior (front) and posterior (back) • Secretes nine hormones that regulate many body functions. • Controls the functions of several other endocrine glands. • Too much = gigantism; too little = pituitary dwarfism

  17. Hypothalamus • Above and attached to the pituitary. • Controls the secretions of the pituitary. • Interactions between the nervous and endocrine systems take place here.

  18. Thyroid Gland • Located at the base of the neck. Wraps around the upper part of the trachea. • Plays a major role in regulating the body’s metabolism. • Produces thyroxine (remember what that does?). This requires iodine.

  19. Hyper vs Hypo thyroidism

  20. Parathyroid Glands (four of ‘em) • Found on the back surface of the thyroid. • Hormones from here act to maintain homeostasis of calcium levels in the blood. • PTH also affects other organ systems to help provide proper nerve and muscle function and bone structure.

  21. Adrenal Glands • Sit on top of the kidneys. • Release hormones that help the body deal with stress • Two parts: • Adrenal cortex (outside) • produces corticosteroids. • Adrenal medulla (inside) • produces epinephrine and norepinephrine • Responsible for the “fight or flight” response when an organism is stressed.

  22. Pancreas • Has both endocrine and exocrine functions. • Produces insulin and glucagon to keep blood sugar levels stable. • Insulin stimulates cells to remove glucose out of the bloodstream • Glucagon causes break down of glycogen and release of glucose into the bloodstream. • Insulin’s target cells are found in the liver, skeletal muscles and fat tissue.

  23. Reproductive Glands (Gonads) • Produce gametes and secrete sex hormones. • In Females: • Gonads = Ovaries • Produce eggs • Estrogen, progesterone • In Males: • Gonads = Testes • Produce sperm • Testosterone

More Related