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ORGANS OF THE ENDOCRINE
SYSTEM
Pituitary gland
Thyroid gland
Parathyroid gland
Adrenal gland
Pineal gland
Pancreas
Gonads

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The Pituitary Gland
• “Hypophysis” = master
gland / pituitary gland
• Pea sized gland
• In hypophyseal fossa of
sphenoid
• Connect to hypothalmus
via infundimulum
• Secretes several
hormones

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The Pituitary Gland
• Two lobes:
1. Posterior pituitary (lobe):
• Composed of nervous
tissue
• Connected to
hypothalmus
1. Anterior pituitary (lobe)
(adenohypophysis)
• Glandular tissue
Anterior
lobe
Posterior
lobe

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Posterior Lobe
• Posterior lobe
• A downgrowth of hypothalums
• Hypothalums = emotional center

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Posterior Lobe - Hormones
• Produced by hypothalamus…released by
posterior lobe
• Oxytocin
• Stimulates contractions in childbirth
• Causes release of breast milk
• Antidiuretic hormone (ADH)
• Causes kidneys to reabsorb water

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Anterior Lobe
• Controlled by hypothalmus
• Secretes several hormones into blood stream

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Anterior Pituitary Hormones
1. Growth hormone (GH)
2. Thyroid-stimulating hormone (TSH) or
thyrotropin
3. Adrenocorticotropic hormone (ACTH)
4. Follicle-stimulating hormone (FSH)
5. Luteinizing hormone (LH)
6. Prolactin (PRL)
• Know names and abbreviations

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Anterior Pituitary Hormones
• All are proteins (water soluble)
• Use cAMP to cause changes in cell
• TSH, ACTH, FSH, and LH are all tropic
hormones
• Tropic hormones regulate other endocrine
glands

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Growth Hormone (GH)
• Targets bone and skeletal muscle
• Helps increase body mass
• Promotes protein synthesis
• encourages fat use

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Imbalances of Growth Hormone
• Hypersecretion
• In children results in gigantism
• In adults results in acromegaly
• Hyposecretion
• In children results in pituitary
dwarfism
gigantism
acromegaly

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• Stimulates the activity of
the thyroid
• Negative feedback
controls production
Thyroid-Stimulating Hormone (Thyrotropin)

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Adrenocorticotropic Hormone
(Corticotropin) (ACTH)
• Stimulates the adrenal gland to release
corticosteroids
• Such as epinephrine
• External factors alter release
• fever, hypoglycemia, and stressors

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Gonadotropins
• Regulate gamete production in gonads
1. Follicle-stimulating hormone (FSH)
2. Luteinizing hormone (LH)
• FSH stimulates gamete (egg or sperm)
production
• LH promotes production of gonadal hormones
• Present after onset of puberty

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Prolactin (PRL)
• Stimulates milk production
• Blood levels rise toward the end of pregnancy
• Suckling stimulates PRH release and
promotes continued milk production

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THYROID GLAND
Metabolism control
•Thyroid hormone
•Calcitonin

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Thyroid Gland
• Located in the throat inferior to Adam’s apple
• produces thyroid hormone
• To make thyroid hormone you need iodine
• thyroglobulin + iodine = thyroid hormone

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Thyroid Hormone
• Major metabolic hormone
• Increases metabolic rate and heat production
• Plays a role in:
• Maintenance of blood pressure
• Regulation of tissue growth
• Development of skeletal and nervous systems
• Reproductive capabilities

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Synthesis and Regulation of
Thyroid Hormone
• Cells require iodine to synthesize TH
• Regulated by negative feedback
• TH inhibits TSH production

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Homeostatic Imbalances of TH
• Hyposecretion in adults — goiter formation
• Enlarged thyroid
• Caused by lack of iodine
• Iodine fortified salt
• Hypersecretion — Graves’ disease
• Antibodies mimic TSH
• Too much TH produced
• Protruding eyes.

20. Copyright © 2011 Pearson Education, Inc. Figure 15.10
goiter

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Calcitonin
• Also produced by thyroid
• Lowers blood calcium (Ca2+
)
• Inhibits osteoclasts
• Causes calcium absorption  into urine
• Production triggered by high blood Ca2+

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PARATHYROID GLANDS

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Parathyroid Glands
• tiny glands embedded in posterior thyroid
• Secrete parathyroid hormone (PTH)
• PTH — important in Ca2+
levels

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Parathyroid Hormone (PTH)
• Functions opposite to calcitonin
• Produced when low blood Ca2+
levels
• Stimulates osteoclasts
• digest bone  release Ca2+
• Kidneys resorb Ca2+
• Negative feedback regulation:
• rising Ca2+
inhibits PTH release

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ADRENAL GLANDS

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Adrenal Glands
• Location: suprarenal = above the kidneys
• Two main regions
• Adrenal cortex — glandular tissue
• secrete corticosteroids
• Adrenal medulla — nervous tissue
• Sympathetic nervous system
• Secrete epinephrine

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Corticosteriods
• Three types produced:
1. Mineralocorticoids – Aldosterone
2. Glucocorticoids – cortisol / cortisone
3. Gonadocorticoids – sex hormones

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Mineralocorticoids
• Regulate electrolytes (primarily Na+
and K+
)
• blood volume, blood pressure
• Aldosterone potent mineralocorticoid
• Na+
reabsorption / water retention by kidneys
Glucocorticoids
• Cortisone and cortisol
• Helps resist stressors
• Helps regulates blood sugar

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Imbalances of Glucocorticoids
• Hypersecretion —Cushing’s syndrome
• Depresses the immune system
• Promotes changes in cardiovascular, neural, and GI
function
• Preparing for stress
• weight gain
• Hyposecretion — Addison’s disease
• Weight loss, severe dehydration, and hypotension

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Gonadocorticoids
• Sex hormones = androgens (male sex hormones)
• In tissues converted to testosterone or
estrogens in females
• Contribute to:
• Onset of puberty
• Secondary sex characteristics

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Adrenal Medulla
• Secretes epinephrine and norepinephrine
• hormones cause “fight or flight”
• Blood diverted to brain, heart, and skeletal
muscle
• glucose levels rise
• Blood vessels constrict
• heart beats faster

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PINEAL GLAND AND
PANCREASE

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Pineal Gland
• Small gland hangs from roof of third ventricle
• Secretes melatonin…derived from serotonin
• Melatonin affects
• sexual maturation
• Day/night cycles
• body temperature, sleep,
appetite

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Pancreas
• Has exocrine and endocrine cells
• Produce pancreatic juice for digestion (exocrine)
• Produce hormones (endocrine)
• Regulate blood sugar
• α cells produce glucagon
• when “glucose is gone”
• β cells produce insulin
• When blood glucose is high

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Glucagon / Insulin
• Glucagon targets liver:
• Gluconeogenesis — produces glucose from
glycogen stores
• Releases glucoses into blood
• Insulin targets tissues
• Causes uptake of glucose into cells

36. Copyright © 2011 Pearson Education, Inc. Figure 15.18
Liver
Liver
Tissue cells
Stimulates glucose uptake by cells
Stimulates
glycogen
formationPancreas
Pancreas
Insulin
Blood
glucose
falls to
normal
range.
Stimulates
glycogen
breakdown
Blood
glucose
rises to
normal
range.
Glucagon
Stimulus
Blood
glucose level
Stimulus
Blood
glucose level
GlycogenGlucose
GlycogenGlucose
Glucagon / Insulin

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Diabetes Mellitus
• Low insulin signaling
• Low levels of production or low activity of insulin
• Symptoms
• Polyuria —huge urine output
• Polydipsia —excessive thirst
• Polyphagia —excessive hunger
• Hyperinsulinism:
• Too much insulin; hypoglycemia, can cause
unconsciousness

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GONADS
Ovaries, placenta and testes

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Ovaries and Placenta
• Ovaries produce estrogens and progesterone:
• Maturation of female reproductive organs
• Female secondary sexual characteristics
• Breast development and mensturation
• Placenta secretes estrogens, progesterone, and
human chorionic gonadotropin (hCG)
• Pregnancy tests look for hCG

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Testes
• Produce testosterone
• Maturation of male reproductive organs
• Male secondary sexual characteristics
• Needed for sperm production

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Other Organs Produce Hormones
• Kidneys
• Erythropoietin  red blood cell production
• Adipose tissue
• Leptin  appetite control
• Thymus
• Lymph cell development
• Heart
• Blood pressure and volume
• GI cells
• Stimulate digestion