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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 7 and 23
The Endocrine System
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Chemical Regulating Systems: Overview
• Neurotransmitters: neuron to neuron
communication across a synapse.
• Hormones: cell to cell communication molecules
• Made in gland(s) or cells
• Transported by blood (humoral) over long
distances.
• Act by binding to receptors
• Activates physiological response
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
The pituitary is two fused glands
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Neurohormones: secreted into the Blood by Neurons
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-12: Synthesis, storage, and release of posterior pituitary hormones
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Hypothalamic-hypophyseal
Portal system
Anterior/Posterior pituitary gland secretions
• Anterior Pituitary: 6 hormones
• Prolactin
• Growth hormone
• Follicle stimulating hormone
• Luteinizing hormone
• Thyroid stimulating hormone
• Adrenocorticotropic hormone
• Posterior Pituitary: 2 hormones
• Vasopressin
• oxytocin
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Oxytocin
vasopressin
Prolactin
Growth hormone
TSH
ACTH
FSH
LH
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Hypothalamic hormones: control anterior pituitary
• Dopamine / prolactin releasing hormone
• Thyrotropin releasing hormone
• Corticotropin-releasing hormone
• Growth hormone-releasing hormone / growth
hormone-inhibiting hormone
• Gonadotropin-releasing hormone
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Terminology
• Tropic hormone:
• A hormone that controls the secretion of
another hormone is known as a trophic
(tropic) hormone.
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Anterior pituitary: Three Levels of Integration
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Figure 7-13: Hormones of the hypothalamic-anterior pituitary pathway
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Negative Feedback Controls:
Long & Short Loop Reflexes
Short
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long
Figure 7-14: Negative
feedback loops in the
hypothalamicanterior
pituitary pathway
Negative Feedback Controls:
Long & Short Loop Reflexes
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 7-15: Control pathway for cortisol secretion
Thyroid
Thyroid hormones are not
Essential for life but can
Affect quality of life
Increase oxygen consumption
*Protein catabolism
Nervous system development
*increase activity in Na/K
ATPase pumps
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Thyroid Gland: Hormones and Iodine Metabolism
• C-cells – calcitonin
• Follicle cells – thyroid hormones – T3, T4
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Thyroid Gland: Hormones and Iodine Metabolism
Figure 23-7b: The thyroid gland
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Thyroid hormones are AMINES from tyrosine:
Carry iodine.
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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T3 & T4 Control Pathways & Diseases from
Malfunction
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Figure 23-12: Thyroid hormone pathway
Neurohormones: secreted into the Blood by Neurons
• Adrenal Medulla–catecholamines; fight or flight
• Mostly epinephrine
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Sex hormones
Glucocorticoids – cortisol
Mineralcorticoids - aldosterone
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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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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
Bone remodeling
BLOOD CALCIUM
Osteoblast activity:
Osteoclast activity:
Bone deposition
Bone resorption
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Osteoporosis
• Excessive loss of calcium from bones.
• When blood calcium is depleted, bones lose their mineral
mass and progressively become porous. The bone matrix
becomes weaker and increasingly vulnerable to fracture.
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Osteoporosis; What Causes it?
•
1. Lack of estrogen
• Estrogen stimulates the osteoblasts to store calcium
• This can be disrupted in overtraining/undereating female athletes
• When body fat is very low or calorie intake is not high enough, females may
cease menstruation.
•
2. Dietary calcium deficiency
•
3. Lack of regular exercise: weight bearing or resistance training makes bone
respond!
•
4. Excessive protein intake (in post-menopausal women)
• Ammonium (NH3) waste from protein is buffered by calcium then excreted
in the urine.
•
5. Excessive alcohol intake: a diuretic that causes calcium to be excreted in
the urine
•
6. smoking: decreases activity of osteoblasts.
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3 hormones that control calcium balance
• Parathyroid hormone (PTH)
• Calcitriol
• Calcitonin
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• Stimulus for release is low
calcium levels
• PTH increases Ca++ levels
• PTH mobilizes Ca++ from
bone
• Renal Ca++ absorption
• Indirectly Ca++ intestinal
absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Calcitriol; reinforces plasma Ca++ increasing effects
of PTH; made from vitamin D
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Calcitonin
• Calcitonin is released when Ca++ goes up.
• Opposite of PTH
• Decreases bone resorption
• Increases renal calcium excretion.
• Released from C cells of the thyroid gland.
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Calcium Metabolism:
Figure 23-20: Calcium balance in the body
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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