Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Presentation 19 - Chemical Signals In Animals

  • Login to see the comments

  • Be the first to like this

Presentation 19 - Chemical Signals In Animals

  1. 2. Key concepts <ul><li>Hormones are compounds produced in one part of the body and transported to another location to produce specific responses; small amount s can induce substantial responses. </li></ul><ul><li>Chemical signals produced by the body are mostly produced by glands . </li></ul><ul><li>Hormones either affect a target effector organ directly or via the signal transduction pathway . </li></ul><ul><li>Effects of hormones vary depending on whether they bind to a receptor in the plasma membrane or within the nucleus of a cell. </li></ul><ul><li>Action of hormones is controlled by feedback mechanisms . </li></ul><ul><li>Hormones are classified by mode of transport or through chemical composition . </li></ul><ul><li>Diseases in the endocrine system occur when levels of hormones released are at an abnormal level or when receptors of that particular hormone are damaged. </li></ul>
  2. 3. Endocrine system <ul><li>Hormone-secreting cells </li></ul><ul><li>Chemical signals secreted into body fluids, eliciting responses in target cells </li></ul><ul><li>Functions with NS in maintaining homeostasis </li></ul><ul><li>Effects are slower and longer-lasting </li></ul>
  3. 4. Maintenance of Homeostasis by the ES and NS <ul><li>Neurosecretory cells – nerve cells that secrete hormones into bloodstream (eg. epinephrine ) </li></ul><ul><li>Feedback regulation </li></ul><ul><ul><li>Positive feedback </li></ul></ul><ul><ul><ul><li>Suckling  release of oxytocin  milk secretion </li></ul></ul></ul><ul><ul><li>Negative feedback </li></ul></ul><ul><ul><ul><li>Control of blood calcium and glucose levels </li></ul></ul></ul>
  4. 5. Invertebrate Endocrine Systems <ul><li>Hydra –control method of reproduction </li></ul><ul><li>Mollusks –controls egg-laying </li></ul><ul><li>Arthropods – extensive endocrine systems for molting and maturity </li></ul><ul><ul><li>Ecdysone  molting and promotion of adult features </li></ul></ul><ul><ul><li>Brain hormone (BH)  regulates production of ecdysone </li></ul></ul><ul><ul><li>Juvenile hormone (JH)  retention of larval characteristics </li></ul></ul>
  5. 6. Chemical signals and their modes of action most peptides, proteins and glycoproteins steroids and thyroid hormones
  6. 7. Importance of signal transduction pathways <ul><li>1) Different pathways in different cells  different responses to the same signal </li></ul><ul><li>2) Amplification of the single signal allows small amounts of hormones to have a large effect </li></ul>
  7. 8. Vertebrate endocrine systems <ul><li>Hypothalamus integrates endocrine and nervous functions </li></ul><ul><li>Neurosecretory cells of hypothalamus produce trophic/tropic hormones </li></ul><ul><ul><li>Stored and secreted by posterior pituitary </li></ul></ul><ul><ul><li>Affect anterior pituitary’s release of own hormones </li></ul></ul>
  8. 9. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
  9. 10. Table 45.1 (continued ) Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
  10. 11. Feedback control loops: a closer look <ul><li>Regulation of thyroid hormones </li></ul><ul><li>Regulation of glucose in the blood </li></ul>
  11. 12. Hormones and the female reproductive cycle
  12. 13. Hormones control the reproductive cycle of human females
  13. 14. Performance-enhancing drugs

×