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Transcript of Chapter 9 The Endocrine System. Functions of Endocrine System Second messenger system of the body ...
![Page 1: Chapter 9 The Endocrine System. Functions of Endocrine System Second messenger system of the body Uses chemical messages (hormones) that are released.](https://reader035.fdocuments.us/reader035/viewer/2022062500/5697c0061a28abf838cc56f9/html5/thumbnails/1.jpg)
Chapter 9The
Endocrine System
![Page 2: Chapter 9 The Endocrine System. Functions of Endocrine System Second messenger system of the body Uses chemical messages (hormones) that are released.](https://reader035.fdocuments.us/reader035/viewer/2022062500/5697c0061a28abf838cc56f9/html5/thumbnails/2.jpg)
Functions of Endocrine SystemFunctions of Endocrine System Second messenger system of the body
Uses chemical messages (hormones) that are released into the blood
Hormones control several major processesReproductionGrowth and developmentMobilization of body defensesMaintenance of much of homeostasisRegulation of metabolism
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Hormone OverviewHormone Overview Hormones
produced by specialized cells
Cells secrete hormones into extracellular fluids
Blood transfers hormones to target sites
Hormones regulate activity of other cells
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The Chemistry of HormonesThe Chemistry of Hormones Amino acid-based
hormones
- Proteins
- Peptides
- Amines
Steroids – made from cholesterol
Prostaglandins – made from highly active lipids
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Mechanisms of Hormone ActionMechanisms 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 working of the cells
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Effects Caused by HormonesEffects 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
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Steroid Hormone Action Diffuse through
membrane of target cells
Enter the nucleus
Bind to a specific protein
Bind to specific sites on DNA
Activate genes that result in synthesis of new proteins
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Nonsteroid Hormone ActionNonsteroid Hormone Action binds to membrane
does not enter cell
Sets off a series of reactions that activates an enzyme
Catalyzes a reaction that produces a second messenger molecule
Oversees additional intracellular changes to promote a specific response
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Control of Hormone ReleaseControl of Hormone Release Most hormone levels in the blood are maintained by
negative feedback
A stimulus or low hormone levels in the blood triggers the release of more hormone
Hormone release stops once an appropriate level in the blood is reached
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Positive FeedbackPositive Feedback
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Hormonal Stimuli of Hormonal Stimuli of Endocrine GlandsEndocrine Glands
- activated by other hormones
Humoral Stimuli of Humoral Stimuli of Endocrine GlandsEndocrine Glands
- changing blood levels of certain ions stimulate hormone release
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Pituitary HormonesPituitary HormonesThe main hormones
• ACTH – adrenocorticotropic hormone
• ADH – anti-diuretic hormone, or vasopressin
• FSH – follicle-stimulating hormone
• GH – growth hormone
• LH – luteinizing hormone
• PRL – prolactin
• TSH – thyroid-stimulating hormone
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Neural Stimuli of Endocrine GlandsNeural Stimuli of Endocrine Glands
Nerve impulses stimulate hormone release
Most are under control of the sympathetic nervous system
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Other Hormone-Producing TissuesOther Hormone-Producing Tissues
Parts of the small intestine
Parts of the stomach
Kidneys
Heart
Placenta
Many other areas have scattered endocrine cells
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Developmental AspectsDevelopmental Aspects
Most endocrine organs operate smoothly until old age, but here are some changes:
Menopause is brought about by lack of efficiency of the ovaries
Problems associated with reduced estrogen are common
Growth hormone production declines with age
Many endocrine glands decrease output with age