overview of endocrine glands and hormones

1. Anatomy and Physiology of The
Endocrine System
ATS Unit 5

2. Goals
• Discuss the anatomy of the endocrine system
• Identify and describe important hormones.
• Discuss how the endocrine system interacts
with other systems in the body.

3. Endocrine System Basics
• The endocrine system includes all of the
glands and tissues that produce hormones in
our body.
– Hormones are chemical messages secreted
directly into the blood stream that control and
modify a huge number of bodily functions.
– The endocrine system is one of the two systems of
communication in the body (the other is the
nervous system).

4. Glands
• Glands are specialized tissues that excrete
some substance.
– Endocrine glands (also called ductless glands)
secrete chemicals inside of the body, directly into
the blood stream.
– Other glands excrete substances outside the body
or in the respiratory, digestive, urinary or
reproductive tracts.
– Glands are commonly made of cuboidal
epithelium.

5. Hormones
• Chemical messengers, similar to
neurotransmitters, that act on tissue to elicit a
targeted response.
– From the Greek word for “excite”
– Three classes of hormones (based on chemistry)
• Amines are derived from a single amino acid (epinephrine,
dopamine)
• Peptides are made of chains of amino acids, or proteins from
3 to over 200 (ghrelin, insulin)
• Steroids are made from cholesterol (fat based) and include
androgens, estrogens, and glucocorticoids.

6. The Pituitary Gland
• Called the “Master Gland”
because it releases many
hormones that regulate other
glands.
• Located just under the brain, and
has an anterior and posterior
lobe.
• It communicated regularly with
the hypothalamus (a part of the
brain that monitors physiological
status, content of blood, etc.) and
can adjust these factors as
needed.

7. Hormones of the Pituitary Gland
Anterior
• Growth Hormone
• Prolactin
• Thyroid Stimulating
Hormone
• Adrenocorticotropic
Hormone
• Follicle Stimulating
Hormone
• Luteinizing Hormone
Posterior
• Vasopressin (Antidiuretic
Hormone)
• Oxytocin
Melanocyte Stimulating Hormone is release by cells in-between the lobes

8. The Thyroid
• Butterfly Sharped and located in the neck, this
gland releases three hormones:
– Thyroxine and Triodothyronine: work together to
control rate of glucose and oxygen metabolism,
protein synthesis, and break down of stored
energy.
– Calcitonin: regulates amount of Calcium in blood
by stimulating osteoblasts to add calcium to
bone, therefore lowering the blood levels.

9. The Parathyroid Glands
• These are tiny glands located on
either side of the thyroid. They
only produce one hormone.
– Parathyroid Hormone has one job,
which is to increase blood levels of
calcium. It does this in 2 ways:
• Stimulates osteoclast to release calcium
from bone.
• Reduce the amount of calcium
eliminated by the kidneys.

10. Adrenal Glands
• Two glands
(each two
glands in one)
that sit on top
of each kidney
They are
controlled by
the
adrenocorticotr
opic hormones
from the
pituitary.

11. Hormones of the Adrenal Glands
Cortex
• Mineralocorticoids (esp.
Aldosterone) which help
regulate the levels of
electrolytes in the blood
stream (mostly potassium and
sodium)
• Glucocorticoids (cortisone and
cortisol) that increase the
levels of glucose on the blood.
• Androgens, which are similar
to male sex hormones but are
in both genders.
Medulla
• Epinephrine, hormone of
the sympathetic nervous
system. Increase respiratory
rate cardiac output,
metabolism, etc..
• Norepinephrine works with
epinephrine, increased
vascular tone and improves
focus and concentration.

12. Gonads
Ovaries
• These produce estrogen
and progesterone which
stimulate female sex
characteristics and the
monthly cycle.
• They respond to FSH and LH
from the anterior pituitary
gland.
Testes
• Testosterone develops the
male sex organs and
secondary sex
characteristics.
• They respond to LH from
the anterior pituitary gland.

13. Pancreas
• While most of the pancreas
serves to provide digestive
enzymes, small clusters of cells
serve as an endocrine gland.
– Islets of Langerhans:
• produce insulin which has 4 jobs:
– Facilitates transport on glucose into cells
(lowering blood levels)
– Promotes fatty acid transport into cells.
– Promotes amino acid transport into
cells.
– Stimulates protein synthesis.
• Make Glucagon
– Works as the opposite of insulin and
increases blood glucose by releasing it
from liver.

14. Pineal Gland
• Located in the third ventricle of the brain, this
tiny gland makes Melatonin.
– Melatonin drops body temperature and has some
relationship to the sleep-wake cycle.
– Release is stimulated by light levels detected by
eyes.

15. Hormones Produces Elsewhere
• Prostaglandins are released by many tissues in the
body, and activity depends on their origin. Generally,
they act to constrict or relax blood vessels and cause
muscle contracts as in labor.
• Neurohormones are released in the brain that travel to
the body tissues. For example, the hypothalamus sends
messengers to the pituitary gland.
• Leptin is produces by fat cells to suppress appetite.
• Ghrelin is mad in the stomach and stimulates appetite.

16. Control of Hormones
• Release and action of hormones typically
follow a negative feedback loop (review).
• Many hormones work as antagonistic pairs
that regulate the same function.
• Hormones and glands are also controlled by
the nervous system which can control by
direct monitoring and response, or indirectly
by emotional or situational triggers.