Chapter 11
The Great Communicator
© 2009 Delmar, Cengage 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 to secrete or separate.
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Functions of the
Endocrine System
• 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:
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one pituitary gland
one thyroid gland
four parathyroid glands
two adrenal glands
one pancreas
one thymus
one pineal gland
two gonads
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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:
anterior and posterior.
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Pituitary Gland
• Controls all other glands
• Located within the sphenoid bone of the skull
• Divided into 2 lobes
– Anterior lobe
– Posterior lobe
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The Anterior Pituitary Gland
• Secretions of the anterior
pituitary gland:
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thyroid stimulating hormone (TSH)
adrenocorticotropic hormone (ACTH)
follicle-stimulating hormone (FSH)
luteinizing hormone (LH)
interstitial cell-stimulating hormone
(ICSH)
– prolactin
– growth hormone (GH)
– melanocyte-stimulating hormone
(MSH)
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Anterior Lobe
• Growth Hormone (Somatropin)
• Thyroid Stimulating Hormone (TSH)
• Gonadotropic Hormones
– Ovaries
• Follicle stimulating hormone (estrogen)
• Luteinizing Hormone : formation of corpus luteum
– Testes
• Follicle stimulating hormone (development of sperm cells)
• Luteinizing Hormone : testosterones
• Prolactin (mammary gland development)
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• Adrenocorticotropic Hormone (ACTH)
– Adrenal glands
– Production of corticosteriods
• Melanocyte stimulating hormone (MSH)
– melanin pigment in skin and hair
– Involved in ability to undergo chameleonlike color changes
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The Posterior Pituitary Gland
• Secretions of the posterior pituitary gland:
– antidiuretic hormone (ADH)
– oxytocin
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Posterior Lobe
1. Antidiuretic hormone (ADH)
– Limits development of large volume of urine by
reabsorbing water by kidneys
2. Oxytocin
– Stimulates milk production and contraction of uterus
during parturition
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The Thyroid Gland
• The thyroid gland is a butterfly-shaped gland
that secretes the following:
– triiodothyronine (T3)
– thyroxine (T4)
– calcitonin
• The combining forms for the thyroid gland
are thyr/o and thyroid/o.
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Thyroid Gland
• Regulates growth and metabolism
• Over or under production of iodine
• Calcitonin maintains balance of calcium
in the blood by decreasing
In birds causes molting and other behaviors linked to
Changes in daylight.
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January 7, 2015
• From memory • List the names of the glands belonging to the
Endocrine System:
1.
2.
3.
4.
5.
6.
7.
8.
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The Parathyroid Glands
• The parathyroid glands are usually four glands
located on the surface of the thyroid gland.
• The parathyroid glands secrete parathormone.
• The combining form for the parathyroid glands is
parathyroid/o.
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Parathyroid Gland
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•
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“Near” thyroid gland / 2 on each side
Parathyroid Hormone (PTH)
Regulates calcium
Maintains balance of calcium in blood by
decreasing
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The Adrenal Glands
• The adrenal glands are two glands located cranial to each kidney;
they consist of a cortex and a medulla.
– Ad- means toward.
– Ren/o means kidney.
• The adrenal cortex secretes
– mineralocorticoids
– glucocorticoids
– and androgens (sex hormones)
• .
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Adrenal Glands
• The adrenal medulla secretes
– epinephrine (adrenoline)
– and norepinephrine
• The combining forms for the adrenal glands
are adren/o and adrenal/o.
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The Pancreas
• The pancreas is a gland located
near the proximal duodenum that
has exocrine and endocrine
functions.
• The endocrine functions of the
pancreas maintain blood glucose
levels.
• The pancreas secretes insulin and
glucagon.
• The combining form for the
pancreas is pancreat/o.
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Pancreas
• Insulin
– Use and storage of carbohydrates (sugar)
– Decrease blood glucose levels
• Glucagon
– Increase blood glucose levels
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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 which is responsible for
production of white blood cells (T- lymphocyte cells) /
immunity
• In adulthood becomes fatty piece of tissue
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The Pineal Gland
• The pineal gland is located near midline in the central portion of
the brain and functions in maintaining circadian rhythm.
• The pineal gland secretes melatonin.
• Resemble pinecone
• The combining form for the pineal gland is pineal/o.
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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.
• Secretions of the ovaries:
– estrogen
– progesterone
• .
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The Testes
• The testes are the male gonads.
• Secretion of the testes:
– testosterone
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Hyperadrenocorticism
• Over production of glucocorticoid (hormone)
• Commonly called Cushings Disease
– An opposite disease is Addison’s where there is a
deficiency
Signs:
Polydypsia
Polyuria
Body fat distribution
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Pathological Conditions
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Hyperthyroidism
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Common in aging cats
Excessive production of thyroid hormone
Can feel an enlarged thyroid gland
Can be treated with medication
Surgical removal of the thyroid gland
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Signs of Hyperthyroidism
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Weight loss (increased metabolism)
Polyuria
Polydipsia
Meowing
Aggression
Affection
• (Behavior changes)
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Diabetes Mellitus
• Insulin is hormone that transports blood
glucose to be stored (as glycogen)and used
for energy needs of cells
• Pancreas doesn’t produce insulin, too much
glucose in blood
• Results in low pH of blood (acid)
• Ketoacidosis = low blood pH and ketones (which
are by products of fat metabolism)
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• Ketoacidosis is result of no production
of insulin = blood glucose (“sugar”)
• Hypoglycemic is the opposite and is the
result of overdose of insulin!
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Things to remember about diabetes
• Signs of diabetes:
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Often overweight
Middle aged – senior
Breed predisposition
Cats
Polydipsia
Polyuria
Sudden weight loss
cataracts
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Things to remember
Diabetes can be treated but not cured:
balancing between too much insulin and
too little insulin
– difficult for owners to understand initially
– treatment is lifetime
• Too much insulin can kill
• Too little can result in death also
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Medical Terms for the
Endocrine System
• Additional terms for endocrine system
tests, pathology, and procedures can be
found in the text.
• Review StudyWARE to make sure you
understand these terms.
© 2009 Delmar, Cengage Learning