chapter 23
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Chapter 23. Adrenal glands Thyroid hormones Growth hormone Tissue and bone growth Calcium balance. Review of Endocrine Principles. Hypothalamic-pituitary control system Several hormones controlled by hypothalamic and anterior pituitary trophic hormones Feedback patterns - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Chapter 23
Adrenal glands
Thyroid hormones
Growth hormone
Tissue and bone growth
Calcium balance
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Review of Endocrine Principles Hypothalamic-pituitary control system
Several hormones controlled by hypothalamic and anterior pituitary trophic hormones
Feedback patterns Negative feedback:
Simple Pathway-Blood glucose level decreasing shuts off insulin secretion Complex Pathway-use the hypothalamic-pituitary control system, where the
feedback signal may be the hormone itself Hormone receptors
May be on surface or inside the cell Cellular responses
Target cells respond by altering existing proteins or making new proteins Magnitude of target cell response
Depends on number of receptors and amount of active hormone Endocrine pathologies
Excess hormone secretion Inadequate hormone secretion Abnormal target cell response to the hormone
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Adrenal Glands
Structure and function of the adrenal gland
Figure 23-1a
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Adrenal Glucocorticoids
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Adrenal Glands
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Adrenal Cortex Secretes Steroid Hormones
1. Aldosterone (Mineralcorticoid)
2. Glucocorticoids Cortisol
3. Sex Hormones
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Adrenal Glucocorticoids
Synthesis pathways for steroid hormones
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Cortisol
The HPA pathway for the control of cortisol secretion
Corticotropin Releasing HormoneCorticotropin Releasing Hormone
Adrenocorticotropic HormoneAdrenocorticotropic Hormone
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Circadian Rhythm of Cortisol Secretion
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Cortisol
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Cortisol
Promotes gluconeogenesis
Causes breakdown of skeletal muscle proteins
Enhances lipolysis
Suppresses the immune system
Causes negative calcium balance
Influences brain function
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Cortisol: Therapeutic Drug
Suppresses the immune system
Inhibits the inflammatory response
Used to treat Bee stings, poison ivy, and pollen allergies
Prevents rejection of transplanted organs
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Hypercortisolism
Hypercortisolism: Excess cortisol in the bodyCushings Syndrome: Hormonal disorder caused by prolonged
exposure to excess cortisol (including iatrogenic). Signs and Symptoms
Hyperglycemia Muscle protein breakdown Excess deposits of extra fat in trunk and face Thin arms and legs Thin skin and bruising
Three causes of hypercortisolism: Adrenal tumor that autonomously secretes cortisol (Primary
Hypercortisolism) Pituitary tumor that autonomously secretes ACTH (Secondary
Hypercortisolism or Cushing’s Disease) Iatrogenic hypercortisolism
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Hypercortisolism
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Hypocortisolism
Less common than Cushing’s syndrome
Addison’s disease Hyposecretion of all adrenal steroid hormones
Autoimmune destruction of adrenal cortex
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Thyroid: Structure
Figure 23-7a
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Thyroid: Structure
Figure 23-7b
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Thyroid
Thyroid hormones are made from iodine and tyrosine
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Thyroid
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Hyperthyroidism
Increases oxygen consumption and metabolic heat production
Increase protein catabolism and may cause muscle weakness
Hyperexcitable reflexes and psychological disturbances
Influence -adrenergic receptors in the heart
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Hypothyroidism
Slow metabolic rate and oxygen consumption
Decreases protein synthesis
Slowed reflexes, slow speech and thought processes, and feelings of fatigue Cretinism in infants
Bradycardia
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Pathway of Thyroid Hormone Control
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Thyroid
A man with goiter due to excessive TSH stimulation
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Thyroid
Goiter can occur in both hyperthyroidism and hypothyroidism
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Thyroid
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Normal Growth
Growth hormone and other hormones
An adequate diet
Absence of stress
Genetics
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Pathway of Growth Hormone Control
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Growth Hormone
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Growth Hormone
Severe GH deficiency leads to dwarfism
Oversecretion of GH in children leads to giantism
Oversecretion of GH in adults leads to acromegaly
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Three Individuals with Acromegaly
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Bone growth
Linear growth of long bones takes place at the epiphyseal plates
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Compactbone
Osteoblast
Dir
ec
tio
n o
f g
row
th
Chondrocyte
Cartilage
owth
Newly calcifiedbone
Bone gr
Dividingchondrocytes
add lengthto bone.
Chondrocytesproducecartilage.
Oldchondrocytesdisintegrate.
Osteoblasts laydown bone on
top of cartilage.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-19 (1 of 5)
Bone growth
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-19 (2 of 5)
Bone growth
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Compactbone
Chondrocyte
Dividingchondrocytes
add lengthto bone.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-19 (3 of 5)
Bone growth
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Compactbone
Chondrocyte
Cartilage
Dividingchondrocytes
add lengthto bone.
Chondrocytesproducecartilage.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-19 (4 of 5)
Bone growth
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Compactbone
Chondrocyte
Cartilage
Dividingchondrocytes
add lengthto bone.
Chondrocytesproducecartilage.
Oldchondrocytesdisintegrate.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-19 (5 of 5)
Bone growth
Epiphysisis the endof a long
bone.
Diaphysisis the
shaft of along bone.
Epiphyseal plate is thesite of bone growth.
Diaphysis
Compactbone
Osteoblast
Dir
ec
tio
n o
f g
row
th
Chondrocyte
Cartilage
owth
Newly calcifiedbone
Bone gr
Dividingchondrocytes
add lengthto bone.
Chondrocytesproducecartilage.
Oldchondrocytesdisintegrate.
Osteoblasts laydown bone on
top of cartilage.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Calcium Balance
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Calcium
Important signal molecule
Part of intercellular cement that holds cells together at tight junction
Cofactor in the coagulation cascade
Affects the excitability of neurons
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Calcium Balance in the Body
Ca2+
Small intestine
Dietarycalcium
Calciumin feces
[free Ca2+]0.001 mM
Kidney
Ca2+
in urine
Ca2+ inkidney tubules
Calcitrol(PTH, prolactin)
Active transport
Some calcium is secreted into the small intestine.
Cells
[Ca2+]
2.5 mM
PassivefiltrationCalcitonin
Ca2+PTH
Calcitonin
PTH
CalcitriolCortisol
Bone ECF
Electrochemicalgradient
PTH = parathyroid hormone
KEY
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Calcium Balance in the Body
[Ca2+]
2.5 mM
ECF
PTH = parathyroid hormone
KEY
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Calcium Balance in the Body
[free Ca2+]0.001 mM
Active transport
Cells
[Ca2+]
2.5 mM
ECF
Electrochemicalgradient
PTH = parathyroid hormone
KEY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-20 (3 of 5)
Calcium Balance in the Body
[free Ca2+]0.001 mM
Active transport
Cells
[Ca2+]
2.5 mM
Calcitonin
Ca2+PTH
Calcitriol
Cortisol
Bone ECF
Electrochemicalgradient
PTH = parathyroid hormone
KEY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-20 (4 of 5)
Calcium Balance in the Body
Ca2+
Small intestine
Dietarycalcium
[free Ca2+]0.001 mM
Calcitrol(PTH, prolactin)
Active transport
Cells
[Ca2+]
2.5 mM
Calcitonin
Ca2+PTH
Calcitriol
Cortisol
Bone ECF
Electrochemicalgradient
PTH = parathyroid hormone
KEY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-20 (5 of 5)
Calcium Balance in the Body
Total body calcium = intake output
Ca2+
Small intestine
Dietarycalcium
Calciumin feces
[free Ca2+]0.001 mM
Kidney
Ca2+
in urine
Ca2+ inkidney tubules
Calcitrol(PTH, prolactin)
Active transport
Some calcium is secreted into the small intestine.
Cells
[Ca2+]
2.5 mM
PassivefiltrationCalcitonin
Ca2+PTH
Calcitonin
PTH
Vitamin D
Cortisol
Bone ECF
Electrochemicalgradient
PTH = parathyroid hormone
KEY
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 23-21
Calcium Balance
Osteoclasts are responsible for bone resorption
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Calcium Balance
Parathyroid hormone Mobilizes calcium from bone
Enhances renal reabsorption
Indirectly increases intestinal absorption
Vitamin D (Calcitriol)
Calcitonin (from Thyroid)
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Calcium Balance: Parathyroid Glands
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Calcium Balance
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Endocrine Control of Calcium Balance
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Calcitonin
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Osteoporosis
Normal bone (left) and bone loss in osteoporosis (right)