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Chapter 16:
The Endocrine System
Arnold Adolph Berthold 1803 – 1861
Founder of Endocrinology
Berthold’s Experiment in Roosters….
Castration
Castration &
Reimplantation
of testis
Castration &
Transplantation
of testis
Berthold’s Conclusion...
-A secretory, blood-borne product of the transplanted testes
is responsible for the normal development of the birds in the
second and third group
Today, it is called TESTOSTERONE
-’problem’: no one knows why Berthold did the experiment in
the first place…. No clear rationale for it.
Figure 16.1: Location of the major endocrine organs of the body, p. 605.
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
(on dorsal aspect
of thyroid gland)
Thymus gland
Adrenal glands
Pancreas
Ovary
(female)
Testis
(male)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.3: PIP second-messenger mechanism of amino acid-based hormones, p. 608.
Extracellular fluid
Hormone
DAG
1
4
2
Receptor Gq
Catecholamines
TRH
ADH
GnRH
Oxytocin
Cytoplasm
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
GTP
GTP
3
GTP
5
Active
protein
kinase C
PIP2
GDP
Phospholipase C
IP3
Inactive
protein
kinase C
Triggers responses
of target cell
5
Endoplasmic
reticulum
6
Ca2+
Ca2+-calmodulin
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.4: Direct gene activation mechanism of steroid hormones, p. 609.
Steroid
hormone
Cytoplasm
Steroid
hormone
Receptorchaperonin
complex
Receptor-hormone
complex
Binding
Transcription
mRNA
Molecular
chaperones
Hormone
response
elements
Chromatin
mRNA
Nucleus
New protein
Ribosome
Translation
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.5: Three types of endocrine gland stimuli, p. 612.
1 Capillary blood contains low
concentration of Ca2+, which
stimulates…
Capillary
(low Ca2+ in blood)
Thyroid gland
(posterior view)
Parathyroid
glands
1 Preganglionic SNS fiber stimulates
adrenal medulla cells…
CNS
(spinal cord)
Preganglionic
SNS fiber
1 The hypothalamus secretes
hormones that…
Hypothalamus
2 …stimulate
the anterior
pituitary gland
to secrete
hormones
that…
Pituitary
gland
Medulla of
adrenal
gland
Thyroid
gland
Parathyroid
glands
Adrenal
cortex
Gonad
(Testis)
PTH
2 …secretion of parathyroid
hormone (PTH) by parathyroid
glands
Capillary
2 …to secrete catecholamines
(a) Humoral
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
(b) Neural
3 …stimulate other endocrine glands
to secrete hormones
(c) Hormonal
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.6: Relationships of the pituitary gland and hypothalamus, p. 613.
Hypothalamic
neurons in the
paraventricular nuclei
Neurons
in the ventral
hypothalamus
Hypothalamic
neurons in the
supraoptic nuclei
Infundibulum
(connecting stalk)
Superior
hypophyseal
artery
Hypothalamichypophyseal tract
Hypophyseal portal system
• Primary capillary
plexus
• Hypophyseal
portal veins
• Secondary capillary
plexus
Anterior lobe
Neurohypophysis
(storage area for
hypothalamic
hormones)
Posterior
lobe
Secretory cells of
adenohypophysis
Venule
TSH, FSH, LH,
ACTH, GH, PRL
Venule
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Inferior
hypophyseal
artery
Oxytocin
ADH
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.7: Metabolic actions of growth hormone (GH), p. 615.
Inhibits GHRH release
Stimulates GHIH release
Feedback
mechanism
Inhibits GH synthesis
and release
Hypothalamus
secretes growth
hormone – releasing
Anterior hormone (GHRH), and
pituitary somatostatin (GHIH)
Key:
Growth hormone
Increases, stimulates
Direct effects
Reduces, inhibits
Initial stimulus
Liver and
other tissues
Physiological response
Result
Insulin-like growth
factors (IGFs)
Anti-insulin
actions
Indirect
growth-promoting
actions
Skeletal effects
Extraskeletal
effects
Fat
Carbohydrate
metabolism
Increased cartilage
formation and
skeletal growth
Increased protein
synthesis, and
cell growth and
proliferation
Increased
lipolysis
Increased blood
glucose and other
anti-insulin effects
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.8: Gross and microscopic anatomy of the thyroid gland, p. 620.
Colloid-filled
Follicle cells
follicles
Hyoid bone
Thyroid cartilage
Epiglottis
Internal carotid
artery
External carotid
artery
Superior thyroid
artery
Common carotid
artery
Inferior thyroid
artery
Isthmus of
thyroid gland
Trachea
Left subclavian
artery
Left lateral lobe
of thyroid gland
Brachiocephalic
artery
Aorta
Parafollicular cell
(a)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
(b)
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.11: The parathyroid glands, p. 624.
Pharynx
(posterior
aspect)
Thyroid
gland
Capillary
Parathyroid
glands
Chief
cells
Esophagus
Trachea
(a)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Oxyphil
cells
(b)
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.12: Effect of parathyroid hormone on bone, the intestine, and the kidneys, p. 625.
Hypocalcemia (low blood
calcium) stimulates
parathyroid glands
Key:
= Ca2+ ions
= PTH molecules
Rising Ca2+ in
blood inhibits
PTH release
PTH release from
parathyroid glands
PTH:
Activates
osteoclasts;
calcium and
phosphate
ions released
into blood
Bone
Intestine
Increases
calcium
absorption
from food
Promotes activation
Kidney
of vitamin D
Increases
calcium
reabsorption
Bloodstream
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.13: Microscopic structure of the adrenal gland, p. 626.
Capsule
Zona
glomerulosa
Adrenal
gland
Zona
fasciculata
• Medulla
• Cortex
Zona
reticularis
Kidney
Adrenal
medulla
(a)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
(b)
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.16: Stress and the adrenal gland, p. 631.
Stress
Short term
More prolonged
Hypothalamus
Nerve impulses
CRH (corticotropinreleasing hormone)
Spinal cord
Corticotroph
cells of
anterior
pituitary
Preganglionic
sympathetic
fibers
To target in blood
Adrenal
cortex
ACTH
Adrenal
medulla
Short-term
stress response
1. Increased heart rate
2. Increased blood pressure
Catecholamines
3. Liver converts glycogen to glucose
(epinephrine
and releases glucose to blood
and norepinephrine) 4. Dilation of bronchioles
5. Changes in blood flow patterns
leading to decreased digestive
system activity and reduced
urine output
6. Increased metabolic rate
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Mineralocorticoids
Glucocorticoids
Long-term stress response
1. Retention of sodium and 1. Proteins and fats
water by kidneys
converted to glucose
2. Increased blood volume
or broken down for
and blood pressure
energy
2. Increased blood glucose
3. Suppression of immune
system
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.18: Regulation of blood glucose levels by insulin and glucagon, p. 633.
Stimulates
glucose uptake
by cells
Insulin
Tissue cells
Pancreas
Stimulates
glycogen
formation
Glucose Glycogen
Blood
glucose
falls to
normal
range
Liver
Stimulus:
Rising blood
glucose level
Homeostasis: Normal blood glucose level (about 90 mg/100 ml)
Stimulus:
Declining blood
glucose level
Blood
glucose
rises to
normal
range
Pancreas
Glycogen
Glucose
Stimulates
glycogen
breakdown Glucagon
Liver
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Figure 16.1: Modified to emphasize the relationship between the adrenal glands and the testes and ovaries.
Testes & Ovaries
These gamete producing glands
produce the lion’s share of sex
hormone for each sex. Ovaries
are in females and Testes are in
males. There is, however, an
important role for the adrenal
glands…
Adrenal glands
Ovary
(female)
Testis
(male)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.