Download Figure 23-20

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
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-1a
Adrenal Glucocorticoids
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Figure 23-1b
Adrenal Glands
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Figure 23-1c
Adrenal Cortex Secretes Steroid Hormones
1. Aldosterone (Mineralcorticoid)
2. Glucocorticoids

Cortisol
3. Sex Hormones
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Adrenal Glucocorticoids
Synthesis pathways for steroid hormones
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-2
Cortisol
The HPA pathway for the control of cortisol secretion
Corticotropin Releasing Hormone
Adrenocorticotropic Hormone
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Figure 23-3
Circadian Rhythm of Cortisol Secretion
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Figure 23-4
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
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Hypercortisolism
Hypercortisolism: Excess cortisol in the body
Cushings 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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Figure 23-5
Hypocortisolism
 Less common than Cushing’s syndrome
 Addison’s disease
 Hyposecretion of all adrenal steroid hormones
 Autoimmune destruction of adrenal cortex
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Thyroid: Structure
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Figure 23-7a
Thyroid: Structure
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Figure 23-7b
Thyroid
Thyroid hormones are made from iodine and tyrosine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-8
Thyroid
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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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Figure 23-12
Thyroid
A man with goiter due to excessive TSH stimulation
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Figure 23-13
Thyroid
Goiter can occur in both hyperthyroidism and
hypothyroidism
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Figure 23-14a
Thyroid
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Figure 23-14b
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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Figure 23-16
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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Figure 23-17
Bone growth
Linear growth of long bones takes place at the
epiphyseal plates
Epiphysis
is the end
of a long
bone.
Bone growth
Epiphyseal plate is the
site of bone growth.
Dividing
chondrocytes
add length
to bone.
Chondrocytes
produce
cartilage.
Old
chondrocytes
disintegrate.
Diaphysis
Compact
bone
Chondrocyte
Cartilage
Direction of growth
Diaphysis
is the
shaft of a
long bone.
Osteoblasts lay
down bone on
top of cartilage.
Newly calcified Osteoblast
bone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19
Bone growth
Epiphysis
is the end
of a long
bone.
Diaphysis
is the
shaft of a
long bone.
Epiphyseal plate is the
site of bone growth.
Diaphysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19 (1 of 5)
Bone growth
Epiphysis
is the end
of a long
bone.
Diaphysis
is the
shaft of a
long bone.
Epiphyseal plate is the
site of bone growth.
Dividing
chondrocytes
add length
to bone.
Compact
bone
Chondrocyte
Diaphysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19 (2 of 5)
Bone growth
Epiphysis
is the end
of a long
bone.
Diaphysis
is the
shaft of a
long bone.
Epiphyseal plate is the
site of bone growth.
Dividing
chondrocytes
add length
to bone.
Chondrocytes
produce
cartilage.
Compact
bone
Chondrocyte
Cartilage
Diaphysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19 (3 of 5)
Bone growth
Epiphysis
is the end
of a long
bone.
Diaphysis
is the
shaft of a
long bone.
Epiphyseal plate is the
site of bone growth.
Dividing
chondrocytes
add length
to bone.
Chondrocytes
produce
cartilage.
Old
chondrocytes
disintegrate.
Compact
bone
Chondrocyte
Cartilage
Diaphysis
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19 (4 of 5)
Bone growth
Epiphysis
is the end
of a long
bone.
Bone growth
Epiphyseal plate is the
site of bone growth.
Dividing
chondrocytes
add length
to bone.
Chondrocytes
produce
cartilage.
Old
chondrocytes
disintegrate.
Diaphysis
Compact
bone
Chondrocyte
Cartilage
Direction of growth
Diaphysis
is the
shaft of a
long bone.
Osteoblasts lay
down bone on
top of cartilage.
Newly calcified Osteoblast
bone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-19 (5 of 5)
Calcium Balance
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Calcium Balance in the Body
Small intestine
Dietary
calcium
Calcitrol
(PTH, prolactin)
Some calcium is secreted
into the small intestine.
ECF
Bone
Ca2+
Calcium
in feces
Ca2+
Kidney
Calcitonin
[Ca2+]
PTH
Calcitriol
Cortisol
2.5 mM
Electrochemical
gradient
Passive
filtration
PTH
Calcitonin
Ca2+ in
kidney
tubules
Active
transport
Cells
[free Ca2+]
0.001 mM
KEY
Ca2+
in urine
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
PTH = parathyroid
hormone
Figure 23-20
Calcium Balance in the Body
ECF
[Ca2+]
2.5 mM
KEY
PTH = parathyroid
hormone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-20 (1 of 5)
Calcium Balance in the Body
ECF
[Ca2+]
2.5 mM
Electrochemical
gradient
Active
transport
Cells
[free Ca2+]
0.001 mM
KEY
PTH = parathyroid
hormone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-20 (2 of 5)
Calcium Balance in the Body
ECF
Bone
Ca2+
Calcitonin
[Ca2+]
PTH
Calcitriol
Cortisol
2.5 mM
Electrochemical
gradient
Active
transport
Cells
[free Ca2+]
0.001 mM
KEY
PTH = parathyroid
hormone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-20 (3 of 5)
Calcium Balance in the Body
Small intestine
Dietary
calcium
Ca2+
Calcitrol
(PTH, prolactin)
ECF
Bone
Ca2+
Calcitonin
[Ca2+]
PTH
Calcitriol
Cortisol
2.5 mM
Electrochemical
gradient
Active
transport
Cells
[free Ca2+]
0.001 mM
KEY
PTH = parathyroid
hormone
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-20 (4 of 5)
Calcium Balance in the Body
Small intestine
Dietary
calcium
Calcitrol
(PTH, prolactin)
Some calcium is secreted
into the small intestine.
ECF
Bone
Ca2+
Calcium
in feces
Ca2+
Kidney
Calcitonin
[Ca2+]
PTH
Vitamin D
Cortisol
2.5 mM
Electrochemical
gradient
Passive
filtration
PTH
Calcitonin
Ca2+ in
kidney
tubules
Active
transport
Cells
[free Ca2+]
0.001 mM
KEY
Ca2+
in urine
PTH = parathyroid
hormone
Total body calcium = intake  output
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 23-20 (5 of 5)
Calcium Balance
Osteoclasts are responsible for bone resorption
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Figure 23-21
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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Figure 23-22
Calcium Balance
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Endocrine Control of Calcium Balance
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Figure 23-23
Calcitonin
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Osteoporosis
Normal bone (left) and bone loss in osteoporosis (right)
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Figure 23-24