1. Figure 16.1 Location of selected endocrine organs of the body.
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
(on dorsal aspect
of thyroid gland)
Thymus
Adrenal glands
Pancreas
Ovary (female)
Testis (male)

2. Hormone (1st messenger) binds receptor. Extracellular fluid
Figure Cyclic AMP second-messenger mechanism of water-soluble hormones.
Hormone (1st messenger)
binds receptor. 1
Extracellular fluid
Adenylate cyclase
G protein (GS)
cAMP acti-
vates protein
kinases. 5
Receptor
GDP
Inactive
protein kinase
Active
protein
kinase
Receptor
activates G
protein (GS) 2
G protein
activates
adenylate
cyclase. 3
Adenylate
cyclase
converts ATP
to cAMP (2nd
messenger). 4
Hormones that
act via cAMP
mechanisms:
Epinephrine
ACTH
FSH LH
Triggers responses of
target cell (activates
enzymes, stimulates
cellular secretion,
opens ion channel,
etc.)
Glucagon
PTH
TSH
Calcitonin
Cytoplasm

3. diffuses through the plasma membrane and binds an
Figure Direct gene activation mechanism of lipid-soluble hormones.
Steroid
hormone
Plasma
membrane
Extracellular fluid
The steroid hormone
diffuses through the plasma
membrane and binds an
intracellular receptor. 1
Cytoplasm
Receptor
protein
Receptor-
hormone
complex
The receptor-
hormone complex enters
the nucleus. 2
Hormone
response
elements
Nucleus
The receptor- hormone
complex binds a hormone
response element (a
specific DNA sequence). 3
DNA
Binding initiates
transcription of the
gene to mRNA. 4
mRNA
The mRNA directs
protein synthesis. 5
New protein

4. Figure 16.4 Three types of endocrine gland stimuli.
(a) Humoral Stimulus
(b) Neural Stimulus
(c) Hormonal Stimulus
Capillary blood contains
low concentration of Ca2+,
which stimulates... 1
Preganglionic sympathetic
fibers stimulate adrenal
medulla cells... 1
The hypothalamus secretes
hormones that... 1
Hypothalamus
Capillary (low
Ca2+ in blood)
CNS (spinal cord)
…stimulate
the anterior
pituitary gland
to secrete
hormones
that… 2
Thyroid gland
(posterior view)
Parathyroid
glands
Pituitary
gland
Preganglionic
sympathetic
fibers
Thyroid
gland
Adrenal
cortex
Gonad
(Testis)
Medulla of
adrenal
gland
Parathyroid
glands
PTH
Capillary
…secretion of
parathyroid hormone (PTH)
by parathyroid glands* 2
…to secrete catechola-
mines (epinephrine and
norepinephrine) 2
…stimulate other endocrine
glands to secrete hormones 3

5. Figure 16.4a Three types of endocrine gland stimuli.
(a) Humoral Stimulus
Capillary blood contains
low concentration of Ca2+,
which stimulates… 1
Capillary (low
Ca2+ in blood)
Thyroid gland
(posterior view)
Parathyroid
glands
Parathyroid glands
PTH
…secretion of
parathyroid hormone (PTH)
by parathyroid glands* 2

6. Figure 16.4b Three types of endocrine gland stimuli.
(b) Neural Stimulus
Preganglionic sympathetic
fibers stimulate adrenal
medulla cells… 1
CNS (spinal cord)
Preganglionic
sympathetic
fibers
Medulla of
adrenal
gland
Capillary
…to secrete catechola-
mines (epinephrine and
norepinephrine) 2

7. Figure 16.4c Three types of endocrine gland stimuli.
(c) Hormonal Stimulus
The hypothalamus secretes
hormones that… 1
Hypothalamus
…stimulate
the anterior
pituitary gland
to secrete
hormones
that… 2
Pituitary
gland
Thyroid
gland
Adrenal
cortex
Gonad
(Testis)
…stimulate other endocrine
glands to secrete hormones 3

8. Figure 16.5a Relationships of the pituitary gland and hypothalamus.
Hypothalamic
neurons
synthesize oxytocin
and ADH. 1
Paraventricular
nucleus
Hypothalamus
Supraoptic
nucleus
Oxytocin and ADH are
transported along the
hypothalamic-hypophyseal
tract to the posterior
pituitary. 2
Optic chiasma
Infundibulum
(connecting stalk)
Inferior
hypophyseal artery
Hypothalamic-
hypophyseal
tract
Oxytocin and ADH are
stored in axon terminals
in the posterior pituitary. 3
Axon
terminals
Oxytocin and ADH are
released into the blood
when hypothalamic
neurons fire. 4
Posterior
lobe of
pituitary
Oxytocin
ADH
(a) Relationship between the posterior pituitary and the hypothalamus

9. Figure 16.5b Relationships of the pituitary gland and hypothalamus.
When appropriately
stimulated,
hypothalamic neurons
secrete releasing and
inhibiting hormones
into the primary
capillary plexus. 1
Hypothalamus
Hypothalamic neuron
cell bodies
Superior
hypophyseal artery
Hypophyseal
portal system
Hypothalamic hormones
travel through the portal
veins to the anterior pituitary
where they stimulate or
inhibit release of hormones
from the anterior pituitary. 2
• Primary capillary
plexus
• Hypophyseal
portal veins
• Secondary
capillary
plexus
Anterior lobe
of pituitary
Anterior pituitary
hormones are secreted
into the secondary
capillary plexus. 3
TSH, FSH,
LH, ACTH,
GH, PRL
(b) Relationship between the anterior pituitary and the hypothalamus

10. Figure 16.6 Growth-promoting and metabolic actions of growth hormone (GH).
Hypothalamus
secretes growth
hormone—releasing
hormone (GHRH), and
somatostatin (GHIH)
Inhibits GHRH release
Stimulates GHIH
release
Feedback
Anterior
pituitary
Inhibits GH synthesis
and release
Growth hormone
Indirect actions
(growth-
promoting)
Direct actions
(metabolic,
anti-insulin)
Liver and
other tissues
Produce
Insulin-like growth
factors (IGFs)
Effects
Effects
Carbohydrate
metabolism
Skeletal
Extraskeletal
Fat
Increases, stimulates
Increased protein
synthesis, and
cell growth and
proliferation
Reduces, inhibits
Increased cartilage
formation and
skeletal growth
Increased
fat breakdown
and release
Increased blood
glucose and other
anti-insulin effects
Initial stimulus
Physiological response
Result

11. Figure 16.7 Regulation of thyroid hormone secretion.
Hypothalamus
TRH
Anterior pituitary
TSH
Thyroid gland
Thyroid
hormones
Stimulates
Target cells
Inhibits

12. Figure 16.8 The thyroid gland.
Hyoid bone
Colloid-filled
follicles
Thyroid
cartilage
Epiglottis
Follicle cells
Common
carotid
artery
Superior thyroid
artery
Inferior
thyroid
artery
Isthmus of
thyroid gland
Trachea
Left subclavian
artery
Left lateral lobe
of thyroid gland
Aorta
Parafollicular cell
(a) Gross anatomy of the thyroid gland,
anterior view
(b) Photomicrograph of thyroid gland
follicles (125x)

13. Figure 16.8a The thyroid gland.
Hyoid bone
Thyroid
cartilage
Epiglottis
Common
carotid
artery
Superior thyroid
artery
Inferior
thyroid
artery
Isthmus of
thyroid gland
Trachea
Left subclavian
artery
Left lateral lobe
of thyroid gland
Aorta
(a) Gross anatomy of the thyroid gland, anterior view

14. Figure 16.8b The thyroid gland.
Follicle cells
Colloid-filled
follicles
Parafollicular cell
(b) Photomicrograph of thyroid gland follicles (125x)

15. Figure 16.9 Synthesis of thyroid hormone.
Thyroid follicle cells
Colloid
Thyroglobulin is synthesized and
discharged into the follicle lumen. 1
Tyrosines (part of thyroglobulin
molecule)
Capillary
Iodine is attached to tyrosine
in colloid, forming DIT and MIT. 4
Golgi
apparatus
Rough ER
Thyro-
globulin
colloid
Iodine 3
Iodide
is oxidized
to iodine.
DIT (T2)
MIT (T1)
Iodide (I - ) 2
Iodide (I - ) is trapped
(actively transported in). T4
Iodinated tyrosines are
linked together to form T3
and T4. 5 T3
Lysosome T4
Thyroglobulin colloid is
endocytosed and combined
with a lysosome. 6 T3 T4
Lysosomal enzymes cleave
T4 and T3 from thyroglobulin
colloid and hormones diffuse
into bloodstream. 7
Colloid in
lumen of
follicle T3
To peripheral tissues

16. Figure 16.10 Thyroid disorders.

17. Figure 16.11 The parathyroid glands.
Pharynx
(posterior
aspect)
Chief
cells
(secrete
parathyroid
hormone)
Thyroid
gland
Parathyroid
glands
Oxyphil
cells
Esophagus
Trachea
Capillary
(a)
(b)

18. Figure 16.11a The parathyroid glands.
Pharynx (posterior
aspect)
Thyroid gland
Parathyroid glands
Esophagus
Trachea
(a)

19. Figure 16.11b The parathyroid glands.
Chief cells (secrete
parathyroid hormone)
Oxyphil cells
Capillary
(b)

20. Figure 16.12 Effects of parathyroid hormone on bone, the kidneys, and the intestine.
Hypocalcemia (low blood Ca2+) stimulates
parathyroid glands to release PTH.
Rising Ca2+ in
blood inhibits
PTH release.
Bone
PTH activates
osteoclasts: Ca2+
and PO43S released
into blood. 1 2
PTH increases
Ca2+ reabsorption
in kidney
tubules.
Kidney
PTH promotes
kidney’s activation of vitamin D,
which increases Ca2+ absorption
from food. 3
Intestine
Ca2+ ions
Bloodstream
PTH Molecules

21. Figure 16.13 Microscopic structure of the adrenal gland.
Hormones
secreted
Capsule
Zona
glomerulosa
Aldosterone
Zona
fasciculata
Adrenal gland
Cortex
• Medulla
Cortisol
and
androgens
• Cortex
Zona
reticularis
Kidney
Medulla
Adrenal
medulla
Epinephrine
and NE
(a) Drawing of the histology of the
adrenal cortex and a portion of
the adrenal medulla
(b) Photomicrograph (160x)

22. Figure 16.13a Microscopic structure of the adrenal gland.
Capsule
Zona
glomerulosa
Zona
fasciculata
Adrenal gland
Cortex
• Medulla
• Cortex
Zona
reticularis
Kidney
Medulla
Adrenal
medulla
(a) Drawing of the histology of the
adrenal cortex and a portion of
the adrenal medulla

23. Figure 16.13b Microscopic structure of the adrenal gland.
Hormones
secreted
Capsule
Zona
glomerulosa
Aldosterone
Zona
fasciculata
Adrenal gland
• Medulla
Cortisol
and
androgens
• Cortex
Zona
reticularis
Kidney
Adrenal
medulla
Epinephrine
and NE
(b) Photomicrograph (160 x )

24. water; increased K+ excretion
Figure Major mechanisms controlling aldosterone release from the adrenal cortex.
Primary regulators
Other factors
Blood volume
and/or blood
pressure
K+ in blood
Stress
Blood pressure
and/or blood
volume
Hypo-
thalamus
Heart
Kidney
CRH
Direct
stimulating
effect
Anterior
pituitary
Renin
Initiates
cascade
that
produces
ACTH
Atrial natriuretic
peptide (ANP)
Angiotensin II
Inhibitory
effect
Zona glomerulosa
of adrenal cortex
Enhanced
secretion
of aldosterone
Targets
kidney tubules
Absorption of Na+ and
water; increased K+ excretion
Blood volume
and/or blood pressure

25. Figure 16.15 The effects of excess glucocorticoid.

26. Figure 16.16 Stress and the adrenal gland.
Short-term stress
More prolonged stress
Stress
Nerve impulses
Hypothalamus
CRH (corticotropin-
releasing hormone)
Spinal cord
Corticotroph cells
of anterior pituitary
Preganglionic
sympathetic
fibers
To target in blood
Adrenal cortex
(secretes steroid
hormones)
Adrenal medulla
(secretes amino acid-
based hormones)
ACTH
Catecholamines
(epinephrine and
norepinephrine)
Mineralocorticoids
Glucocorticoids
Short-term stress response
Long-term stress response
1. Increased heart rate
2. Increased blood pressure
3. Liver converts glycogen to glucose and releases
glucose to blood
4. Dilation of bronchioles
5. Changes in blood flow patterns leading to decreased
digestive system activity and reduced urine output
6. Increased metabolic rate
1. Retention of sodium
and water by kidneys
2. Increased blood volume
and blood pressure
1. Proteins and fats converted
to glucose or broken down
for energy
2. Increased blood glucose
3. Suppression of immune
system

27. Pancreatic islet (of Langerhans) • (Glucagon- producing) cells
Figure Photomicrograph of differentially stained pancreatic tissue.
Pancreatic
islet (of
Langerhans)
• (Glucagon-
producing)
cells
• (Insulin-
producing)
cells
Pancreatic
acinar
cells (exocrine)

28. Stimulates glucose uptake by cells
Figure Regulation of blood glucose levels by insulin and glucagon from the pancreas.
Stimulates glucose uptake by cells
Insulin
Tissue cells
Stimulates
glycogen
formation
Pancreas
Glucose
Glycogen
Blood
glucose
falls to
normal
range.
Liver
Stimulus
Blood
glucose level
Stimulus
Blood
glucose level
Blood
glucose
rises to
normal
range.
Pancreas
Liver
Glucose
Glycogen
Stimulates
glycogen
breakdown
Glucagon

29. Table 16.1 Pituitary Hormones: Summary of Regulation and Effects (1 of 4)

30. Table 16.1 Pituitary Hormones: Summary of Regulation and Effects (2 of 4)

31. Table 16.1 Pituitary Hormones: Summary of Regulation and Effects (3 of 4)

32. Table 16.1 Pituitary Hormones: Summary of Regulation and Effects (4 of 4)

33. Table 16.2 Major Effects of Thyroid Hormone (T4 and T3) in the Body (1 of 2)

34. Table 16.2 Major Effects of Thyroid Hormone (T4 and T3) in the Body (2 of 2)

35. Table 16.3 Adrenal Gland Hormones: Summary of Regulation and Effects

36. Table 16.4 Symptoms of Insulin Deficit (Diabetes Mellitus)

37. Table Selected Examples of Hormones Produced by Organs Other Than the Major Endocrine Organs (1 of 2)

38. Table Selected Examples of Hormones Produced by Organs Other Than the Major Endocrine Organs (2 of 2)

39. A Closer Look 16.1 Sweet Revenge: Taming the DM Monster?

40. Making Connections Homeostatic Interrelationships Between the Endocrine System and Other Body Systems