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Chapter 11
The Great Communicator
The Endocrine System
Copyright © 2006 Thomson Delmar Learning
Functions of the
Endocrine System
• The endocrine system is composed of
ductless glands that secrete chemical
messengers called hormones into the
bloodstream
– endo- means within
– -crine means secrete or separate
• Hormones enter the bloodstream and are
carried throughout the body to affect a
variety of tissues and organs
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Structures of the
Endocrine System
• The glands of the normal endocrine
system include
–
–
–
–
–
–
–
–
one pituitary gland
one thyroid gland
four parathyroid glands
two adrenal glands
one pancreas
one thymus
one pineal gland
two gonads
Copyright © 2006 Thomson Delmar Learning
The Pituitary Gland
• The pituitary gland is
located at the base of the
brain just below the
hypothalamus
– The hypothalamus
secretes releasing and
inhibiting factors that
affect the release of
substances from the
pituitary gland
– The combining form for
the pituitary gland is
pituit/o
– The pituitary gland has
two lobes: the anterior
and posterior
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The Anterior Pituitary Gland
• The anterior pituitary
gland secretes
– thyroid stimulating
hormone (TSH)
– adrenocorticotropic
hormone (ACTH)
– follicle-stimulating
hormone (FSH)
– luteinizing hormone
(LH)
– Interstitial cellstimulating hormone
(ICSH)
– prolactin
– growth hormone (GH)
– melanocyte-stimulating
hormone (MSH)
Copyright © 2006 Thomson Delmar Learning
The Posterior Pituitary Gland
• The posterior
pituitary gland
secretes
– antidiuretic
hormone
(ADH)
– oxytocin
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The Thyroid Gland
• The thyroid gland
is a butterflyshaped gland
that secretes
– triiodothyronine
(T3)
– thyroxine (T4)
– calcitonin
• The combining
forms for the
thyroid gland
are thyr/o and
thyroid/o
Copyright © 2006 Thomson Delmar Learning
The Parathyroid Glands
• The parathyroid glands are usually four glands located
on the surface of the thyroid gland
• The parathyroid glands secrete parathromone
• The combining form for the parathyroid glands is
parathyroid/o
Copyright © 2006 Thomson Delmar Learning
The Adrenal Glands
• The adrenal glands are two glands located cranial to
each kidney that consist of a cortex and medulla
– ad- means toward
– ren/o means kidney
• The adrenal cortex secretes mineralocorticoids,
glucocorticoids, and androgens
• The adrenal medulla secretes epinephrine and
norepinephrine
• The combining forms for the adrenal glands are adren/o
and adrenal/o
Copyright © 2006 Thomson Delmar Learning
The Pancreas
• The pancreas is a
gland located near
the proximal
duodenum that has
both exocrine and
endocrine functions
• The endocrine
functions of the
pancreas maintains
blood glucose levels
• The pancreas
secretes insulin and
glucagon
• The combining form
for the pancreas is
pancreat/o
Copyright © 2006 Thomson Delmar Learning
The Thymus
• The thymus is a gland predominant in young animals
located near midline in the cranioventral portion of the
thoracic cavity
• The thymus secretes thymosin
• The combining form for the thymus is thym/o
Copyright © 2006 Thomson Delmar Learning
The Pineal Gland
• The pineal gland is located near midline in the central
portion of the brain and functions in maintaining circadian
rhythm
• The thymus secretes melatonin
• The combining form for the pineal gland is pineal/o
Copyright © 2006 Thomson Delmar Learning
The Gonads
• The gonads are glands that produce gametes (sex cells)
• The gonads are the ovaries in females and the testes in
males
• The combining form for the gonads is gonad/o
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The Ovaries
• The ovaries are
the female gonads
• The ovaries
secrete
– estrogen
– progesterone
• The ovaries are
covered in more
detail in the chapter
on reproduction
Copyright © 2006 Thomson Delmar Learning
The Testes
• The testes are
the male
gonads
• The testes
secrete
– testosterone
• The testes are
covered in
more detail in
the chapter on
reproduction
Copyright © 2006 Thomson Delmar Learning
Medical Terms for the Endocrine
System
• Additional terms for endocrine
system tests, pathology, and
procedures can be found in the text
• Review the Flash! CD program to
make sure you understand these
terms
Copyright © 2006 Thomson Delmar Learning