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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 23
Endocrine Control of Growth
and Metabolism
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
About this Chapter
• How several key hormone pathways influence
metabolism
• How cortisol is produced & regulated; how it
impacts many tissues
• How thyroid hormones are regulated and their
effect on targets
• The role of growth hormone in growth &
development
• Calcium metabolism and its role in bones and cell
regulations
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Endocrine Control in Review
• Hypothalamic – pituitary: feedback loop & trophic
control
• Hormones can have receptors on many diverse
tissues
• Usually initiating protein change or synthesis in
target cells
• Problems come from too much or too little
hormone
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Adrenal Cortex: Steroid Hormone Production
• Aldosterone, sex hormones, cortisol
• Synthesized from cholesterol–steroid ring
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Adrenal Cortex: Steroid Hormone Production
Figure 23-2: Synthesis pathways of steroid hormones
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Cortisol Effects: Body Responses to Stress
• Permissive effect on glucagon
• Memory, learning & mood
• Gluconeogenesis
• Skeletal muscle breakdown
• Lipolysis, calcium balance
• Immune depression
• Circadian rhythms
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Cortisol Effects: Body Responses to Stress
Figure 23-4: Circadian rhythm of cortisol secretion
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Control of Cortisol Secretion: Feedback Loops
• External stimuli
• Hypothalamic
• Anterior Pituitary
• Adrenal cortex
• Tissues
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Figure 23-3: The control pathway for cortisol
Endocrine Control: Three Levels of Integration
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Figure 7-13: Hormones of the hypothalamic-anterior pituitary pathway
Cortisol: Role in Diseases and Medication
• Use as immunosuppressant
• Hyperimmune reactions (bee stings)
• Serious side effects
• Hypercortisolism (Cushing's syndrome)
• Tumors (pituitary or adrenal)
• Iatrogenic (physician caused)
• Hypocortisolism (Addison's disease)
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Thyroid Gland: Hormones and Iodine Metabolism
• C-cells – calcitonin (covered later)
• Follicule cells
• Amine hormones:
• thyroxine, T1, T2 & T3
•  growth
•  metabolism
• Thermogenic
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Effects of Thyroid Hormone
• TH is concerned with:
• Glucose oxidation
• Increasing metabolic rate
• Heat production
• TH plays a role in:
• Maintaining blood pressure
• Regulating tissue growth
• Developing skeletal and nervous systems
• Maturation and reproductive capabilities
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Thyroid Hormone
• Thyroid hormone – the body’s major metabolic
hormone
• Consists of two closely related iodine-containing
compounds
• T4 – thyroxine; has two tyrosine molecules plus
four bound iodine atoms
• T3 – triiodothyronine; has two tyrosines with
three bound iodine atoms
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Thyroid Gland: Hormones and Iodine Metabolism
Figure 23-7b: The thyroid gland
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Thyroxine and its precursors: Structure & Synthesis
Figure 23-8: Thyroid hormones are made from tyrosine and iodine
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Thyroxine and its precursors: Structure & Synthesis
Figure 23-9: Thyroid hormone synthesis
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Synthesis of Thyroid Hormone
• Thyroglobulin is synthesized and discharged into
the lumen
• Iodides (I–) are actively taken into the cell, oxidized
to iodine (I2), and released into the lumen
• Iodine attaches to tyrosine, mediated by peroxidase
enzymes, forming T1 (monoiodotyrosine, or MIT),
and T2 (diiodotyrosine, or DIT)
• Iodinated tyrosines link together to form T3 and T4
• Colloid is then endocytosed and combined with a
lysosome, where T3 and T4 are cleaved and diffuse
into the bloodstream
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Transport and Regulation of TH
• T4 and T3 bind to thyroxine-binding globulins
(TBGs) produced by the liver
• Both bind to target receptors, but T3 is ten times
more active than T4
• Peripheral tissues convert T4 to T3
• Mechanisms of activity are similar to steroids
• Regulation is by negative feedback
• Hypothalamic thyrotropin-releasing hormone
(TRH) can overcome the negative feedback
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T3 & T4 Control Pathways & Diseases from
Malfunction
• Hypothalamus
• Anterior Pituitary
• Thyroid
• Hypothyroidism
• Goiter (TSH )
• Grave's disease
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
T3 & T4 Control Pathways & Diseases from
Malfunction
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Figure 23-12: Thyroid hormone pathway
Growth Hormone (GH): Functions & Malfunctions
• Polypeptide H from hypothalamus/anterior
pituitary
•  growth (with T4, sex Hs, paracrines)
•  metabolism
•  protein & bone synthesis
• Regulation – hypothalamus
• Dwarfism
• Acromegaly
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Metabolic Action of Growth Hormone
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Figure 16.6
Growth Hormone (GH): Functions & Malfunctions
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Figure 23-16: Growth hormone pathway
Multiple Hormones Can Target a Cell/Tissue
• Growth H
• Somatomedins
• Thyroxin
• All have receptors
on many tissues
• Stimulate
pathways for
growth
Figure 7-17: A complex endocrine pathway
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Bone Growth and Calcium Metabolism
• Epiphyseal plate – new bone growth site
• Chondrocytes, osteoblasts & calcification build
bone
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Bone Growth and Calcium Metabolism
Figure 23-19: Bone growth at the epiphyseal plate
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Calcium Metabolism:
• Maintain [plasma]: from diet, from bone
"storage", recycled
• Key roles: muscle contraction, bone support, cell
signaling
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Calcium Metabolism:
Figure 23-20: Calcium balance in the body
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Control of Calcium Balance & Metabolism
• Parathyroid H
• Calcitrol
• Vitamin D
• Sun/diet
• Calcitonin
• Thyroid
• C-cells
• (Phosphate balance)
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Figure 23-23: Endocrine control of calcium balance
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Osteoporosis:
Disease of Bone Growth & Calcium Metabolism
• Bone reabsorption
exceeds deposition
• Osteoclasts
mobilize Ca++ to
plasma
• Factors:
inadequate Ca++
intake, genes,
hormones,
smoking
Figure 23-21: Osteoclasts are responsible for bone resorption
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Summary
• In addition to insulin and glucagon, metabolism
is influenced by hormones from adrenal, thyroid,
parathyroid and hypothalamus
• Cortisol  catabolic activities responding to stress
• Growth H  anabolic activities to promote growth
• PTH, cacitrol, & calcitonin balance plasma [Ca++]
for bone synthesis, muscle contraction, & cell
signaling
• Endocrine diseases result from pathway or
glandular hypo or hyper secretion
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings