1. Introduction to the Endocrine System
Chapter 7b
Introduction to the Endocrine System

2. Simple Endocrine Reflex: Parathyroid Hormone
Low plasma
[Ca2+]
Negative feedback
Parathyroid
cell
Parathyroid
hormone
Bone
and
kidney
Bone
resorption
Kidney
reabsorption of
calcium
Production of calcitriol
leads to intestinal
absorption of Ca2+
Plasma
[Ca2+]
Figure 7-10

3. Neurohormones: Major Groups
Adrenal medulla
Catecholamines
Hypothalamus
Anterior pituitary
Posterior pituitary

4. Three levels Endocrine Control Hypothalamic stimulation—from CNS
Pituitary stimulation—from hypothalamic trophic hormones
Releasing factors or Neurohormones
Endocrine gland stimulation—from pituitary trophic hormones
Stimulate other hormones

5. Negative Feedback Controls
Figure 7-14

6. Control Pathway for Cortisol Secretion
Figure 7-15

7. A Complex Endocrine Pathway
HYPOTHALAMUS
Growth hormone is an example of a complex endocrine pathway
Hypothalamus
GHRH
ANTERIOR
PITUITARY
GH cells
in anterior
pituitary GH
Liver
IGFs
Bone and
soft tissue
Growth
Figure 7-17

8. The Pituitary Gland Anatomy
Figure 7-11

9. The Pituitary Gland: Anterior
HYPOTHALAMIC
HORMONES
Neurons in hypothalamus
secreting trophic hormones
Dopamine*
TRH
CRH
PRFs
GHRH*
GnRH
Somatostatin
Portal system
Anterior pituitary
ANTERIOR
PITUITARY
HORMONES
Prolactin
TSH
ACTH GH
FSH LH
Endocrine
cells
(Gonadotropins)
GTFLAP
To target
tissues
ENDOCRINE TARGETS
AND THE HORMONES
THEY SECRETE
Endocrine cells
of the gonads
Thyroid
gland
Adrenal
cortex
Liver
Thyroid
hormones
Estrogens,
progesterone
Cortisol
IGFs
Androgens
NONENDOCRINE
TARGETS
Many
tissues
Germ cells
of the gonads
Breast
Figure 7-13

10. The Hypothalamic-Hypophyseal Portal System
HYPOTHALAMUS 1
Neurons synthesizing
trophic hormones release
them into capillaries of
the portal system.
Capillary bed
Artery 2
Portal vessels carry the
trophic hormones directly
to the anterior pituitary.
POSTERIOR PITUITARY 3
Endocrine cells release
their hormones into the
second set of capillaries
for distribution to the
rest of the body.
Capillary bed
ANTERIOR PITUITARY
Veins
TO TARGET ORGANS
Prolactin
Gonadotropins (LH & FSH) GH
TSH
ACTH
Ovary
Testis
Mammary glands
Musculoskeletal system
Thyroid gland
Adrenal cortex
Gonads
Figure 7-16

11. The Pituitary Gland: Posterior
Posterior pituitary
Vasopressin (ADH)
Oxytocin
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell. 3
Vesicles containing
hormone are stored in
posterior pituitary.
POSTERIOR PITUITARY
Vein 4
Hormones are released
into blood.
Figure 7-12

12. The Pituitary Gland: Posterior
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron.
POSTERIOR PITUITARY
Figure 7-12, step 1

13. The Pituitary Gland: Posterior
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell.
POSTERIOR PITUITARY
Figure 7-12, steps 1–2

14. The Pituitary Gland: Posterior
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell. 3
Vesicles containing
hormone are stored in
posterior pituitary.
POSTERIOR PITUITARY
Figure 7-12, steps 1–3

15. The Pituitary Gland: Posterior
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell. 3
Vesicles containing
hormone are stored in
posterior pituitary.
POSTERIOR PITUITARY
Vein 4
Hormones are released
into blood.
Figure 7-12, steps 1–4

16. The Pituitary Gland: Posterior
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell. 3
Vesicles containing
hormone are stored in
posterior pituitary.
POSTERIOR PITUITARY
Vein 4
Hormones are released
into blood.
Figure 7-12

17. Synergism Permissiveness Antagonism Hormone Interactions
Multiple stimuli—more than additive
1 + 1 = 3
Permissiveness
Need second hormone to get full expression
Antagonism
Glucagons oppose insulin

18. Example of Synergism Glucagon + Epinephrine + Cortisol
Figure 7-18

19. Endocrine Pathologies
Figure 7-19

20. Endocrine Pathologies
Hypersecretion: excess hormone
Tumors or cancer
Autoimmune
Grave’s disease—thyroxin
Hyposecretion: deficient hormone
Goiter—thyroxin
Low Iodine
Diabetes melitus type I—insulin

21. Goiter

22. Pathologies: Abnormal Receptors
Downregulation
Hyperinsulinemia
Transduction abnormalities
Testicular feminization syndrome
Pseudohypothyroidism
Abnormalities of control mechanisms

23. Primary and Secondary Pathologies
Figure 7-20

24. Stress Pathologies: Hypocortisolism
Hyposecretion from
damage to the pituitary
(b)
Hyposecretion from atrophy
of the adrenal cortex
Hypothalamus
CRH
Hypothalamus
CRH
Anterior pituitary
ACTH
Anterior pituitary
ACTH
Adrenal cortex
Cortisol
Adrenal cortex
Cortisol
Symptoms of
deficiency
Symptoms of
deficiency
Figure 7-21

25. Pineal Gland and Melatonin
Influences body clock and antioxidant activity
Other roles need research
SAAD and sexual behavior

26. Pineal Gland and Melatonin
Corpus
callosum
Thalamus
The pineal gland
Figure 7-22 (1 of 3)

27. Pineal Gland and Melatonin
Figure 7-22 (2 of 3)

28. Pineal Gland and Melatonin
Figure 7-22 (3 of 3)

29. Introduction to hormones Classifications and features of hormones
Summary
Introduction to hormones
Classifications and features of hormones
Regulation controlled by the endocrine and nervous systems
Interactions of hormones with other hormones
Endocrine pathologies