1. Chapter 10: The Endocrine System
Essentials of human Anatomy and Physiology
Fifth Edition Seeley, Stephens and Tate
Chapter 10: The Endocrine System

2. The Endocrine System
Living systems require coordination and integration
Endocrine and nervous systems are the control systems of the body
Endocrine control:
Slower
Longer acting
Slide 9.1
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3. The Endocrine System Nervous system control (later)
More rapid
Short duration
The two systems are interrelated
Act to maintain homeostasis
Slide 9.1
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4. The Endocrine System Endocrine glands vs. Exocrine glands
Endocrine glands make hormones
Hormones released into blood
Circulate throughout the body
Act only at “receptor sites” on target cells: very specific
Slide 9.1
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5. The Endocrine System Hormones control several major processes
Reproduction
Growth and development
Mobilization of body defenses
Maintenance of much of homeostasis
Regulation of metabolism
Slide 9.1
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6. Hormone Overview
Hormones (Gr. “to set in motion”) are produced by specialized cells
Blood transfers hormones to target sites
Hormones alter the physiology of other cells
Slide 9.2
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7. The Chemistry of Hormones
Amino acid-based hormones
Proteins
Peptides
Amines
Steroids – made from cholesterol
Prostaglandins – made from highly active lipids
Slide 9.3
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8. Mechanisms of Hormone Action
Hormones affect only certain tissues or organs (target cells or organs)
Target cells must have specific protein receptors
Hormone binding influences the function of the cells
Slide 9.4
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9. Effects Caused by Hormones
Changes in plasma membrane permeability or electrical state
Synthesis of proteins, such as enzymes
Activation or inactivation of enzymes
Stimulation of mitosis
Slide 9.5
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10. Steroid Hormones: Mechanism of Action (DNA or “Gene Expression”)
Hormones diffuse through the plasma membrane of target cells
Enter the nucleus
Bind to a specific protein within the nucleus
Slide 9.6
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11. Steroid Hormone Action
Hormone-protein complex binds to a specific site on the cell’s DNA
Activates genes that result in synthesis of new proteins
New protein influences cell function
Slide 9.6
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12. Steroid Hormone Action
Figure 9.1a
Slide 9.7
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13. Nonsteroid Hormone Action: “Second Messenger System”
Hormone binds to a membrane receptor
Hormone does not enter the cell
Sets off a series of reactions that activates an enzyme
Slide 9.8
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14. Nonsteroid Hormone Action: “Second Messenger System”
Catalyzes a reaction that produces a second messenger molecule
Cyclic AMP (cAMP)
cAMP activates additional intracellular changes to promote a specific response
Slide 9.8
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15. Nonsteroid Hormone Action
Figure 9.1b
Slide 9.9
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16. Control of Hormone Release
Hormone levels in the blood are maintained by negative feedback
A stimulus (like low hormone levels in the blood) triggers the release of more hormone
Hormone release stops once an appropriate level in the blood is reached
Slide 9.10
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17. Hormonal Stimuli of Endocrine Glands
Endocrine glands are activated by other hormones
Figure 9.2a
Slide 9.11
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18. Humoral Stimuli of Endocrine Glands
Changing blood levels of certain ions stimulate hormone release
Figure 9.2b
Slide 9.12
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19. Neural Stimuli of Endocrine Glands
Nerve impulses stimulate hormone release
Most are under control of the sympathetic nervous system
Figure 9.2c
Slide 9.13
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20. Location of Major Endocrine Glands
Figure 9.3
Slide 9.14
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21. Pituitary Gland Size of a grape Hangs by a stalk from the hypothalamus
Protected by the sphenoid bone (what part??)
Has two functional lobes
Anterior pituitary – glandular tissue
Posterior pituitary – nervous tissue
Slide 9.15
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22. Hormones of the Anterior Pituitary
Six anterior pituitary hormones
Two affect non-endocrine targets
Four stimulate other endocrine glands (tropic [“tropic” = “feeding”] hormones)
All six are secreted by the anterior pituitary (glandular tissue)
Slide 9.16
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23. Hormones of the Anterior Pituitary
Characteristics of all anterior pituitary hormones
Proteins (or peptides)
Act through second-messenger systems
Regulated by hormonal stimuli, mostly negative feedback
Slide 9.16
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24. Hormones of the Anterior Pituitary
Figure 9.4
Slide 9.17
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25. Functions of Anterior Pituitary Hormones
Growth Hormone (GH)
Action: growth of skeletal muscles and long bones; maintains size
Target: bone and muscle
Slide 9.18
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26. Functions of Anterior Pituitary Hormones
Prolactin (PRL)
Action: Stimulates and maintains milk production following childbirth
Target: mammary tissue
Function in males is unknown
Slide 9.19
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27. Functions of Anterior Pituitary Hormones
Adrenocorticotropic hormone (ACTH)
Action: Regulates endocrine activity of the adrenal cortex
Target: Cells of adrenal cortex
Slide 9.19
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28. Functions of Anterior Pituitary Hormones
Thyroid-stimulating hormone (TSH)
Action: Influences growth and activity of the thyroid gland
Target: cells of the thyroid gland
Slide 9.19
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29. Functions of Anterior Pituitary Hormones
Gonadotropic hormones
Target: male/female gonads
Action: Follicle-stimulating hormone (FSH)
Stimulates follicle development in ovaries
Stimulates sperm development in testes
Slide 9.20a
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30. Functions of Anterior Pituitary Hormones
Gonadotropic hormones (continued)
Luteinizing hormone (LH)
Action:
Triggers ovulation in females
Causes ruptured follicle to become the corpus luteum in females
Stimulates testosterone production in males (ICSH)
Slide 9.20b
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31. Pituitary - Hypothalamus Relationship
Release of hormones is controlled by the hypothalamus
Hypothalamus produces two hormones
Made by neurons
transported the posterior pituitary by neurons
Slide 9.21
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32. Pituitary - Hypothalamus Relationship
The posterior pituitary is NOT an endocrine gland
Does NOT make hormones
Is NOT glandular
Only releases hormones
Slide 9.21
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33. Hormones of the Posterior Pituitary
Oxytocin
Target: Smooth muscle of uterus, breast
Action:
stimulates contractions of the uterus during labor
causes milk ejection
Slide 9.22
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34. Hormones of the Posterior Pituitary
Antidiuretic hormone (ADH)
Target: Kidney tubules
Action:
Inhibits urine production
In large amounts, causes increased blood pressure (vasopressin)
Slide 9.22
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35. Hormones of the Posterior Pituitary
Figure 9.5
Slide 9.22b
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