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Endocrine System
Chapter 9
Overview of Hormones
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The endocrine and
nervous systems often
work together to bring
about homeostasis.
The blood stream
transports hormones
throughout the body.
Overview of Hormones

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Each hormone acts on
a certain type of tissue
called its target tissue.
Organs, tissues, or
cells lacking the
specific receptor do not
respond to its
stimulating effects.
Negative Feedback Loop
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A decrease in function in response to a
stimulus
The system controls how much product it
makes by shutting down manufacturing when
levels of output or the amount of accumulated
product gets too high
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Example # 1: the regulation of the blood glucose
level in the body
Example # 2: regulation of body temperature
Negative Feedback Loop
Positive Feedback Loop
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An increase in function in response to a
stimulus
“A” produces more of “B” which in turn
produces more of “A”
Only a few positive feedback loops occur in
the human endocrine system.

Example: the process of birthing a child
Positive Feedback Loop
Glands
Glands
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Exocrine glands – secretions released into
ducts opening onto an epithelial surface
Endocrine glands – ductless organs that
secrete their molecules directly into the
bloodstream
Glands

Endocrine glands are
activated by other
hormones
Hypothalamus
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Controls the pituitary gland
Receives information from the nervous
system
Pituitary
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Location: Inferior to the hypothalamus
Known as the master gland
I. Anterior Pituitary
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1. Growth hormone
(GH)
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General metabolic
hormone
Major effects are directed
to growth of skeletal
muscles and long bones
I. Anterior Pituitary
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2. Prolactin (PRL)
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Stimulates and maintains
milk production following
childbirth
Function in males is
unknown
I. Anterior Pituitary

3. Adrenocorticotropic hormone (ACTH)

Regulates endocrine activity of the adrenal cortex
which makes a hormone called cortisol (helps the
body manage stress)
I. Anterior Pituitary

4. Thyroid-stimulating hormone (TSH)

Produces the hormone thyroxine

Regulates the rate of metabolism
I. Anterior Pituitary
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Gonadotropic hormones – Regulate
hormonal activity of the gonads

5. Follicle-stimulating hormone (FSH)
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Stimulates follicle development in ovaries
Stimulates sperm development in testes
I. Anterior Pituitary

Gonadotropic hormones – Regulate
hormonal activity of the gonads

6. Luteinizing hormone (LH)
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Triggers ovulation
Prepares uterus for fertilized egg
Stimulates testosterone production in males
II. Posterior Pituitary
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1. Oxytocin
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Stimulates contractions of the uterus during labor
Causes milk ejection
II. Posterior Pituitary

2. Antidiuretic hormone
(ADH)


Can inhibit urine
production
In large amounts, causes
vasoconstriction leading
to increased blood
pressure
Posterior Pituitary
Anterior Pituitary

Mnemonic Device for anterior and posterior pituitary
gland

Anterior pituitary

FLAT PIG
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1. FSH
2. LH
3. ACTH
4. TSH
5. Prolactin
(Ignore)
6. Growth Hormone
Posterior pituitary

Audio Osmosis = AO

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1. ADH
2. Oxytocin

Anterior Pituitary Gland Chart
Mnemonic Device
(Letter)
Hormone
Targeted Area
Produces
F
L
FSH
LH
Ovaries and Testes
Ovaries and Testes
Sperm and egg
Ovulation and
testosterone
A
T
P
I
G
ACTH
TSH
Prolactin
Ignore
GH
Adrenal Gland
Thyroid
Breast
Muscles and bones
Cortisol
Thryoxine
Milk
Growth of muscles
and bones

Posterior Pituitary Gland Chart
Mnemonic
Device (Letter)
A
Hormone
Targeted Area
ADH
Kidneys
O
Oxytocin
Produces
Inhibit urine
production
Uterus and breast Uterine
contraction and
milk letdown
Pineal
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Location: Between the
left and right
hemispheres (thalamus
region)
Hormone: Melatonin
Function: maintains the
body’s circadian cycle
(a daily cycle of activity
observed in many living
organisms)
Thyroid
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Located in the neck in front of the trachea
Thyroid gland releases the hormone
thyroxine.
Function: regulates the rate of metabolism
Parathyroid
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Location: embedded in back of thyroid gland
Hormone: Parathormone
Function: Controls the metabolism of calcium
Thymus
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Located posterior to the
sternum
Helps develop the
immune system in
infants

Helps lymphocytes to
mature
Adrenal Gland

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Location: on top of
kidney
Hormone: Adrenaline
Function: Raises blood
sugar level and
increases heart beat
and breathing rates
Islets of Langerhans
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Location: Pancreas
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Hormones: Insulin
Produced by beta cells
Function: Stimulates
glucose uptake by cells
Islets of Langerhans
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Location: Pancreas
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Hormone: Glucagon
Produced by alpha cells
Function: Promote
conversion (change of
glycogen to glucose)
Endocrine System Control
Regulation of Blood Sugar
Feedback
insulin
liver stores
sugar
body
cells take
up sugar
from blood
pancreas
high
liver
blood sugar level
(90mg/100ml)
low
triggers
hunger
liver
releases
sugar
pancreas
glucagon
reduces
appetite
Ovary
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Hormones: estrogen
and progesterone
Functions:
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Estrogen helps develop
secondary characteristics
in females
Progesterone prepares
the uterus for the
fertilized ovum and
maintains pregnancy
Testes
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The testes secrete
“male sex hormones”
called androgens.
Testosterone is an
androgen that develops
the secondary
characteristics in men.