1. Chemical Control of the Animal Body: The Endocrine System

2. pineal gland hypothalamus pituitary gland thyroid gland thymus
adrenal glands
(one at
each kidney)
Figure: 23-03
Title:
Major mammalian endocrine glands.
Caption:
pancreas
gonads
testis
ovary

3. II. Hormones—chemical signals of change
A. Classes of animal hormones
1. Peptide hormones
2. Amino acid derivatives
3. Steroid hormones

4. (a) hormone: (1st messenger) (plasma membrane) 1 (extracellular fluid)
(cytoplasm)
activates
(nuclear membrane) 2
cAMP-
synthesizing
enzyme
active
enzyme
Figure: 23-02a
Title:
Modes of action of hormones
Caption:
(a) Peptide and amino-acid hormones, which are not soluble in lipids, (1) bind to receptors on the outside of the target cell's plasma membrane. (2) Hormone-receptor binding activates an enzyme that triggers the synthesis of cyclic AMP (cAMP) from ATP. (3) Cyclic AMP activates enzymes that (4) promote specific cellular reactions, producing new products.
product 4
hormone
receptor
protein
(2nd messenger) 3
activates
enzyme
inactive
reactant
(nucleus)

5. (b) steroid hormone (plasma membrane) 1 (extracellular fluid) (nuclear
hormone-receptor
complex 2
DNA 3
(cytoplasm)
Figure: 23-02b
Title:
Modes of action of hormones
Caption:
(b) Lipid-soluble steroid hormones (1) diffuse readily through the plasma membrane into the target cell and into the nucleus, (2) where they combine with a receptor molecule. (3) The hormone-receptor complex binds to DNA and facilitates the binding of RNA polymerase to promoter sites on specific genes, accelerating (4) the transcription of DNA into messenger RNA (mRNA), which moves out into the cytoplasm. (5) The mRNA then directs protein synthesis.
RNA
polymerase
ribosome
hormone
receptor
protein 5
gene 4
mRNA
protein
synthesized
(nucleus)

6. II. Hormones—chemical signals of change
B. Function of animal hormones
1. Binding to surface receptors
2. Binding to intracellular receptors
3. Negative feedback as a regulatory mechanism for hormone synthesis and release

7. Hormone is distributed throughout the body.
Endocrine cells
release hormone.
Hormone is distributed
throughout the body.
capillary
Hormone enters
bloodstream.
receptor on
target cell
Figure: 23-01
Title:
Endocrine glands, hormones, and target cells.
Caption:
The cells of endocrine glands secrete hormones into the extracellular fluid, from which they diffuse into the capillaries. A hormone binds to (and influences) only those cells with receptors for it. Muscle cells but not nerve cells have receptors for the particular hormone shown here.
hormone-
receptor
complex
SKELETAL MUSCLE TISSUE
binding occurs,
hormonal effects appear
NEURAL TISSUE
no binding, no
hormone effects

8. The mammalian endocrine system
Major endocrine glands
Hypothalamus–
pituitary complex
Anterior pituitary hormones
Posterior pituitary hormones

9. secreted into the blood by neurosecretory cells. PITUITARY
in hypothalamus
HYPOTHALAMUS
hormone
artery
direction of
blood flow
Oxytocin or ADH is
secreted into the blood
by neurosecretory cells.
Figure: 23-04
Title:
The hypothalamus controls the pituitary.
Caption:
Neurosecretory cells of the hypothalamus control hormone release in the anterior lobe of the pituitary by producing hormones (left). These hormones are secreted into a capillary network that carries them to the anterior pituitary. There, each hormone from the hypothalamus stimulates endocrine cells with appropriate receptors to secrete that hormone while leaving other types unaffected. The posterior lobe of the pituitary (right) is an extension of the hypothalamus. Neurosecretory cells in the hypothalamus have cell endings on a capillary bed in the posterior lobe, where the cells release oxytocin or antidiuretic hormone (ADH).
PITUITARY
(anterior lobe)
PITUITARY
(posterior lobe)
capillary
bed
capillary
bed
Hormone is secreted
into the blood by
pituitary cells.
endocrine
cells
artery
vein

11. Figure: 23-T01-1
Title:
Mammalian endocrine glands and hormones.
Caption:
Mammalian endocrine glands and hormones. From "hypothalamus" through "pancreas."

12. Figure: 23-T01-2
Title:
Mammalian endocrine glands and hormones.
Caption:
Mammalian endocrine glands and hormones. From "ovaries" through "fat cells."

13. hypothalamus Hypothalamus sends impulses to posterior pituitary.
hunger
posterior
pituitary
Oxytocin is
released and
carried in blood
to the breast.
Nerve impulses
are sent to
Hypothalamus.
Muscles contract and
squeeze out milk.
Suckling stimulates
nerves in breast.
Figure: 23-06
Title:
Hormones and breastfeeding.
Caption:
The control of milk letdown by oxytocin during breastfeeding is regulated by feedback between an infant and its mother. The cycle begins with the infant’s suckling and continues until the infant is full and stops suckling. With the nipple no longer being stimulated, oxytocin release stops, the muscles relax, and milk flow ceases.
milk
gland
muscle
cells
duct
milk-producing
cells
nipple

14. Figure: 23-05
Title:
When the anterior pituitary malfunctions.
Caption:
An improperly functioning anterior pituitary produces either too much or too little growth hormone. Too little causes dwarfism; too much causes gigantism.

15. The mammalian endocrine system
Thyroid and parathyroid glands
a. Thyroxine and metabolism
b. Hyperthyroidism and Graves' disease

17. (a) larynx thyroid gland esophagus trachea (b) Figure: 23-07 Title:
The thyroid gland.
Caption:
(a) The thyroid gland wraps around the front of the larynx in the neck. (b) Goiter, a condition in which the thyroid gland becomes greatly enlarged, is caused by an iodine-deficient diet.

18. The mammalian endocrine system
3. Pancreas as an endocrine gland
a. Regulation of blood glucose levels by insulin and glucagon
b. Insulin insensitivity and diabetes mellitus

19. insulin-producing cells glucagon-producing cells glucose glycogen
eating
insulin-producing
cells
pancreas
glucagon-producing
cells
glucagon
insulin
Figure: 23-08
Title:
The pancreas controls blood glucose levels.
Caption:
The pancreatic islet cells contain two populations of hormone-producing cells: one producing insulin; the other, producing glucagon. These two hormones cooperate in a two-part negative feedback loop to control blood glucose concentrations.
glucose
glycogen
liver

20. The mammalian endocrine system
4. Sex organs and steroid hormones
a. Puberty and secondary sex characteristics
b. Gamete production

22. The mammalian endocrine system
Adrenal glands
a. Adrenal medulla
1) Produces adrenaline and noradrenaline
a) Released in response to stress or emergency situations
b. Adrenal cortex
1) Produces glucocorticoids
a) Steroid hormones that help regulate glucose metabolism
b) Glucocorticoids and sports medicine
2) Produces aldosterone
Steroid hormone that regulates the sodium content of the blood by affecting the kidneys and sweat glands
3) Testosterone synthesis and the bearded lady

23. adrenal medulla (epinephrine, norepinephrine) adrenal gland
adrenal cortex
(glucocorticoids,
testosterone,
aldosterone)
Figure: 23-09
Title:
The adrenal glands.
Caption:
Atop each kidney sits an adrenal gland, which is a two-part gland composed of very dissimilar cells. The outer cortex secretes steroid hormones; the inner medulla secretes epinephrine and norepinephrine.
kidney

25. The mammalian endocrine system
Kidneys
a. Erythropoietin
1) Response to low oxygen content in the blood
2) Stimulates the production of RBC in the bone marrow
b. Renin
1) Response to low blood pressure
2) Activates the production of angiotensin, which constricts arterioles