1. Chapter 17 Lecture Slides with Animations
Title
Chapter 17
Lecture
Slides
with
Animations
To run the animations you must be in Slideshow View. Use the buttons on the animation to play, pause, and turn audio/text on or off. Please note: once you have used any of the animation functions (such as Play or Pause), you must first click in the white background before you advance the next slide.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Functional Organization of the
Chapter 17
Functional Organization of the
Endocrine System

3. 17.1 Principles of Chemical Communication
Classes of Chemical Messengers
Autocrine chemical messengers: released by cells and have a local effect on same cell type from which chemical signals released; e.g., prostaglandin
Paracrine chemical messengers: released by cells and affect other cell types locally without being transported in blood; e.g., somatostatin
Neurotransmitter: produced by neurons and secreted into extracellular spaces by presynaptic nerve terminals; travels short distances; influences postsynaptic cells; e.g., acetylcholine.
Endocrine chemical messengers: type of intercellular signal. Produced by cells of endocrine glands, enter circulatory system, and affect distant cells; e.g., estrogen

5. Characteristics of the Endocrine System
Glands that secrete chemical messengers (hormones) into circulatory system
Hormone characteristics
Produced in small quantities
Secreted into intercellular space
Transported some distance in circulatory system
Acts on target tissues elsewhere in body
Regulate activities of body structures
Ligands: more general term for chemical signals

6. Comparison of Nervous and Endocrine Systems
Similarities
Both systems associated with the brain
Hypothalamus
Epithalamus
May use same chemical messenger as neurotransmitter and hormone.
Epinephrine
Two systems are cooperative
Nervous system secretes neuroendocrine peptides, or neurohormones, into circulatory system
Some parts of endocrine system innervated directly by nervous system

7. Comparison of Nervous and Endocrine Systems
Differences
Mode of transport
Axon
Blood
Speed of response
Nervous – instant/milliseconds
Endocrine – delayed/seconds
Duration of response
Nervous – milliseconds/seconds
Endocrine – minutes/days
Amplitude vs. frequency

8. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

9. 17.2 Hormones General Characteristics of Hormones Stability
Half-life: The length of time it takes for half a dose of substance to be eliminated from circulatory system
Long half-life: regulate activities that remain at a constant rate through time. Usually lipid soluble and travel in plasma attached to proteins
Short half-life: water-soluble hormones as proteins, epinephrine, norepinephrine. Have a rapid onset and short duration
Communication
Interaction with target cell
Distribution
Hormones dissolve in blood plasma and are transported in unbound or are reversibly bound to plasma proteins.
Hormones are distributed quickly because they circulate in the blood.

10. Protein Bound Transport

13. Patterns of Hormone Secretion
Chronic hormone regulation. Maintenance of relatively constant concentration of hormone. Thyroid hormone.
Acute hormone regulation. Epinephrine in response to stress.
Episodic (Cyclic) hormone regulation. Female reproductive hormones.

14. 17.3 Control of Hormone Secretion
Most hormones controlled by negative feedback systems
Most hormones are not secreted at constant rate, but their secretion is regulated by three different methods
The action of a substance other than a hormone on an endocrine gland.
Neural control of endocrine gland.
Control of secretory activity of one endocrine gland by hormone or neurohormone secreted by another endocrine gland

15. Control by Humoral Stimuli

16. Control by Neural Stimuli

17. Control by Hormonal Stimuli

18. Negative Feedback

19. Positive Feedback

20. 17.4 Hormone Receptors and Mechanisms of Action

21. Target Tissue Specificity and Response
Portion of molecule where hormone binds is called binding site.
If the molecule is a receptor (like in a cell membrane) the binding site is called a receptor site
hormone/receptor site is specific; e.g., epinephrine cannot bind to the receptor site for insulin.
The purpose of binding to target tissue is to elicit a response by the target cell.

22. Decrease in Receptor Number
Normally, receptor molecules are degraded and replaced on a regular basis.
Down-regulation
Rate at which receptors are synthesized decreases in some cells after the cells are exposed to a hormone.
Combination of hormones and receptors can increase the rate at which receptor molecules are degraded. This combined form is taken into the cell by phagocytosis and then broken down.

23. Increase in Receptor Number
Up-Regulation
Some stimulus causes increase in synthesis of receptors for a hormone, thus increases sensitivity to that hormone
For example, FSH stimulation of the ovary causes an increase of LH receptors. Ovarian cells are now more sensitive to LH, even if the concentration of LH does not change. This causes ovulation.

24. Classes of Receptors Lipid-soluble hormones bind to nuclear receptors
Lipid soluble and relatively small molecules; pass through the plasma membrane
React either with enzymes in the cytoplasm or with DNA to cause transcription and translation
Thyroid hormones, testosterone, estrogen, progesterone, aldosterone, and cortisol

25. Classes of Receptors
Water-soluble hormones bind to membrane-bound receptors: integral proteins with receptor site at extracellular surface. Interact with hormones that cannot pass through the plasma membrane.
Hormones
Water-soluble or large-molecular-weight hormones. Attachment of hormone causes intracellular reaction.
Large proteins, glycoproteins, polypeptides; smaller molecules like epinephrine and norepinephrine

27. Action of Nuclear Receptors
Proteins in cytoplasm or nucleus
Hormones bind with intracellular receptor and receptor-hormone complex activate certain genes, causes transcription of mRNA and translation. These proteins (enzymes) produce the response of the target cell to the hormone
Latent period of several hours because time is required to produce mRNA and protein
Processes limited by breakdown of receptor-hormone complex
Estrogen and testosterone produce different proteins in cells that cause the differing secondary sexual characteristics of females and males.

29. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

30. Membrane-Bound Receptors
Intracellular mediators: ions or molecules that enter cell or are produced in cell
Can be produced because of G protein activation
Regulate intracellular enzyme activities

32. Insert table 17.5

33. Receptors that Activate G Proteins

34. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

35. G Proteins that open Calcium ion Channels

36. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

37. G Proteins that Interact with Adenylate Cyclase

38. Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at

39. G Proteins that Interact with other Intercellular Mediators

40. Receptors That Directly Alter the Activity of Intracellular Mediator

41. Receptors That Phosphorylate Intracellular Proteins
Hormones bind to membrane-bound receptors.
Part of receptor protein on inside of membrane acts as an enzyme to phosphorylate proteins
E.g., insulin receptors bound to insulin cause phosphorylation of proteins and cell responds to presence of insulin.

42. Signal Amplification