Download Ch 9 Hypothalamus and Pituitary

FUNCTIONS OF THE ENDOCRINE SYSTEM AND
MAJOR ENDOCRINE ORGANS:
HYPOTHALAMUS AND PITUITARY
Pages 312-317
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THE ENDOCRINE SYSTEM

A control system of the body
 By
way of hormones (chemical messengers) that
are released directly into the blood

Hormones control and/or assist processes like:
 Reproduction
 Growth
and development
 Mobilization of body defenses
 Homeostasis
 Metabolism
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MAJOR ENDOCRINE ORGANS
Pituitary gland
 Hypothalamus
 Thyroid gland
 Parathyroid glands
 Adrenal glands
 Pancreas
 Pineal gland
 Thymus gland
 Gonads (ovaries and testes)

FIGURE 9.3 LOCATION OF THE MAJOR ENDOCRINE ORGANS OF THE BODY.
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands
Pancreas
Ovary (female)
Testis (male)
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FEATURES OF MAJOR ENDOCRINE ORGANS

Some are purely endocrine glands (ductless)
 Hormones
 Anterior

are secreted directly into the blood
pituitary, thyroid, adrenals, parathyroids
Other glands are mixed glands, with both
endocrine and exocrine functions
 Exocrine
glands dump into ducts
 pancreas,
gonads
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PITUITARY GLAND

Referred to as the “master endocrine gland”
 About
the size of a pea
Hangs from the hypothalamus in the brain
 Has two functional lobes

 Anterior
pituitary—glandular tissue
 Produces
 Posterior
hormones
pituitary—nervous tissue
 releases
hormones after neural stimulation
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HYPOTHALAMUS

produces releasing and inhibiting hormones
 These
influence pituitary action
 Such hormones are released into circulation that
connects the hypothalamus to the anterior
pituitary

Synthesizes two hormones:
 oxytocin
and antidiuretic hormone
 Stored in posterior pituitary
FIGURE 9.4 HORMONES RELEASED BY THE POSTERIOR LOBE OF THE PITUITARY AND THEIR TARGET
ORGANS.
Optic
chiasma
Axon
terminals
Hypothalamic
neurosecretory
cells
Hypothalamus
Arterial blood supply
Anterior lobe
of the pituitary
Posterior lobe of pituitary
Capillary bed
Venous drainage
Hormones produced
by the hypothalamus
are released into
blood by nerve
impulses
ADH
Oxytocin
Kidney tubules
Mammary glands
Uterine muscles
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THE HYPOTHALAMUS-POSTERIOR PITUITARY
RELATIONSHIP
The posterior pituitary stores hormones
synthesized by the hypothalamus
 Oxytocin

 Stimulates
uterine contractions
 Causes milk ejection in a breastfeeding woman

Antidiuretic hormone (ADH)
 Inhibits
urine production (diuresis)
 promotes
water reabsorption by the kidneys
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HORMONES OF THE ANTERIOR PITUITARY

Six anterior pituitary hormones
 endocrine
1.
2.
3.
4.
targets (tropic hormones):
Thyroid-stimulating hormone (thyrotropic hormone)
Adrenocorticotropic hormone
Follicle-stimulating hormone
Luteinizing hormone
 nonendocrine
1.
2.
targets:
Growth hormone
Prolactin
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HORMONES OF THE ANTERIOR PITUITARY

Characteristics of all anterior pituitary
hormones
 They
are proteins
 Use a second-messenger systems
 Regulated by hormonal stimuli
 Regulated by feedback inhibition (most often
negative)
FIGURE 9.5 HORMONES OF THE ANTERIOR PITUITARY AND THEIR MAJOR TARGET ORGANS.
Releasing hormones
secreted into portal
circulation
Hypothalamus
Anterior pituitary
Posterior pituitary
Adrenocorticotropic
hormone (ACTH)
Growth hormone (GH)
Bones and muscles Prolactin (PRL) Follicle-stimulating
hormone (FSH)
and luteinizing
Mammary
hormone (LH)
glands
Testes or ovaries
Thyrotropic
hormone (TH)
Thyroid
Adrenal cortex
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ANTERIOR PITUITARY HORMONE FUNCTION

Growth hormone (GH)


Prolactin (PRL)


Stimulates/maintains breast milk production
Adrenocorticotropic hormone (ACTH)


growth of skeletal muscles and long bones
Regulates endocrine activity of the adrenal cortex
Thyrotropic hormone (TH),
A.K.A. thyroid-stimulating hormone (TSH)
 Influences growth and activity of the thyroid gland

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
Gonadotropic hormones
 Regulate
hormonal activity of the gonads
 Follicle-stimulating
hormone (FSH)
Stimulates follicle development in ovaries
 Stimulates sperm development in testes

 Luteinizing
hormone (LH)
Triggers ovulation of an egg in females
 Stimulates testosterone production in males
