1. What role do hormones play in transforming a caterpillar into a butterfly?
Figure 45.1
For the Discovery Video Endocrine System, go to Animation and Video Files.

2. Intercellular communication by secreted molecules
Blood
vessel
Response
(a) Endocrine signaling
Response
(b) Paracrine signaling
Response
(c) Autocrine signaling
Synapse
Neuron
Figure 45.2
Response
(d) Synaptic signaling
Neurosecretory
cell
Blood
vessel
Response
(e) Neuroendocrine signaling

3. Hormones differ in form and solubility
Water-soluble
Lipid-soluble
0.8 nm
Polypeptide:
Insulin
Steroid:
Cortisol
Figure 45.3
Amine:
Epinephrine
Amine:
Thyroxine

4. Receptor location varies with hormone type
Water-
soluble
hormone
Fat-soluble
hormone
Transport
protein
Signal receptor
TARGET
CELL OR
Signal
receptor
Figure 45.5 Receptor location varies with hormone type
Cytoplasmic
response
Gene
regulation
Cytoplasmic
response
Gene
regulation
(a)
NUCLEUS
(b)

5. Cell-surface hormone receptors
Epinephrine
Adenylyl
cyclase
G protein
G protein-coupled
receptor
GTP
Cell-surface hormone receptors
trigger signal transduction
ATP
Second
messenger
cAMP
Figure 45.6
Protein
kinase A
Inhibition of
glycogen synthesis
Promotion of
glycogen breakdown

6. Steroid hormone receptors
are
inside
the cell
and
directly regulate gene expression
Hormone
(estradiol)
Estradiol
(estrogen)
receptor
Plasma
membrane
Hormone-receptor
complex
Figure 45.7
DNA
Vitellogenin
mRNA
for vitellogenin

7. Same receptors but different intracellular proteins
One hormone, different effects
Same receptors but different
intracellular proteins
Different receptors
Epinephrine
Epinephrine
Epinephrine
Epinephrine
 receptor
 receptor
 receptor
 receptor
Glycogen
deposits
Vessel
dilates.
Vessel
constricts.
Glycogen
breaks down
and glucose
is released.
Figure 45.8
(a) Liver cell
(b) Skeletal muscle
blood vessel
(c) Intestinal blood
vessel

8. Specialized role of a hormone in frog metamorphosis
(b)
Figure 45.9

9. Major endocrine glands:
Hypothalamus
Pineal gland
Pituitary gland
Organs containing
endocrine cells:
Thyroid gland
Thymus
Parathyroid glands
Heart
Liver
Adrenal
glands
Stomach
Figure Major human endocrine glands
Pancreas
Testes
Kidney
Kidney
Small
intestine
Ovaries

10. A simple endocrine pathway
Example –
Stimulus
Low pH in
duodenum
S cells of duodenum
secrete secretin ( )
Endocrine
cell
Negative feedback
Blood
vessel
Figure 45.11
Target
cells
Pancreas
Response
Bicarbonate release

11. Maintenance of glucose homeostasis by insulin and glucagon
Body cells
take up more
glucose.
Insulin
Beta cells of
pancreas
release insulin
into the blood.
Liver takes
up glucose
and stores it
as glycogen.
STIMULUS:
Blood glucose level
rises.
Blood glucose
level declines.
Homeostasis:
Blood glucose level
(about 90 mg/100 mL)
Figure Maintenance of glucose homeostasis by insulin and glucagon
STIMULUS:
Blood glucose level
falls.
Blood glucose
level rises.
Alpha cells of pancreas
release glucagon.
Liver breaks
down glycogen
and releases
glucose.
Glucagon

12. Hormonal regulation of insect development
Brain
Neurosecretory cells
Corpus cardiacum
PTTH
Corpus allatum
Low JH
Prothoracic
gland
Ecdysone
Juvenile
hormone
(JH)
Figure 45.13
EARLY LARVA
LATER
LARVA
PUPA
ADULT

13. Endocrine glands in the human brain
Cerebrum
Thalamus
Pineal
gland
Hypothalamus = brain
Cerebellum
Pituitary
gland
Spinal cord
Endocrine glands in the human brain
Figure 45.14
Hypothalamus
Posterior
pituitary
Anterior
pituitary

14. Table 45.1

15. Table 45.1

16. A simple neurohormone pathway
Example
Stimulus
Suckling +
Sensory neuron
Hypothalamus/ posterior pituitary
Neurosecretory cell
Posterior pituitary secretes oxytocin ( )
Positive feedback
Blood vessel
Figure 45.16
Target cells
Smooth muscle in breasts
Response
Milk release

17. Liver, bones, other tissues
Production and release of anterior pituitary hormones
Tropic effects only: FSH LH TSH ACTH
Neurosecretory cells of the hypothalamus
Nontropic effects only: Prolactin MSH
Nontropic and tropic effects: GH
Hypothalamic releasing and inhibiting hormones
Portal vessels
Endocrine cells of the anterior pituitary
Posterior pituitary
Pituitary hormones
Figure 45.17
HORMONE
FSH and LH
TSH
ACTH
Prolactin
MSH GH
TARGET
Testes or ovaries
Thyroid
Adrenal cortex
Mammary glands
Melanocytes
Liver, bones, other tissues

18. A hormone casade pathway Figure 45.18 A hormone cascade pathway
Example
A hormone
casade
pathway
Stimulus
Cold
Sensory neuron –
Hypothalamus secretes thyrotropin-releasing hormone (TRH )
Neurosecretory cell
Blood vessel –
Anterior pituitary secretes thyroid-stimulating hormone (TSH or thyrotropin )
Negative feedback
Figure A hormone cascade pathway
Thyroid gland secretes thyroid hormone (T3 and T4 )
Target cells
Body tissues
Increased cellular metabolism
Response

19. Falling blood Ca2+ level Blood Ca2+ level (about 10 mg/100 mL)
Antagonistic Hormone Pairs control blood calcium levels
Active vitamin D
Stimulates Ca2+ uptake in kidneys
Increases Ca2+ uptake in intestines
PTH
Parathyroid gland (behind thyroid)
Stimulates Ca2+ release from bones
Figure The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals
STIMULUS:
Falling blood Ca2+ level
Blood Ca2+ level rises.
Homeostasis:
Blood Ca2+ level (about 10 mg/100 mL)

20. Summary: Stress and the Adrenal Gland
Nerve signals
Hypothalamus
Spinal cord
Releasing hormone
Nerve cell
Anterior pituitary
Blood vessel
ACTH
Adrenal medulla
Adrenal cortex
Adrenal gland
Kidney
(a) Short-term stress response
Figure Stress and the adrenal gland
(b) Long-term stress response
Effects of epinephrine and norepinephrine:
Effects of mineralocorticoids:
Effects of glucocorticoids:
1. Glycogen broken down to glucose; increased blood glucose
2. Increased blood pressure 3. Increased breathing rate 4. Increased metabolic rate
1. Retention of sodium ions and water by kidneys
1. Proteins and fats broken down and converted to glucose, leading to increased blood glucose
5. Change in blood flow patterns, leading to increased alertness and decreased digestive, excretory, and reproductive system activity
2. Increased blood volume and blood pressure
2. Possible suppression of immune system

21. Signal Transduction Pathway
Example –
Stimulus
Low blood glucose
Pancreas alpha cells
secretes glucagon
Endocrine
cell
Negative feedback
Blood
vessel
Target
cells
Liver
Glycogen breakdown, glucose release into blood
Response

22. You should now be able to:
Distinguish between the following pairs of terms: hormones and local regulators, paracrine and autocrine signals.
Describe the evidence that steroid hormones have intracellular receptors, while water-soluble hormones have cell-surface receptors.
Explain how the antagonistic hormones insulin and glucagon regulate carbohydrate metabolism.
Distinguish between type 1 and type 2 diabetes.

23. Explain how the hypothalamus and the pituitary glands interact and how they coordinate the endocrine system.
Explain the role of tropic hormones in coordinating endocrine signaling throughout the body.
List and describe the functions of hormones released by the following: anterior and posterior pituitary lobes, thyroid glands, parathyroid glands, adrenal medulla, adrenal cortex, gonads, pineal gland.