Introduction to Hormones and

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Chapter 17

• Introduction to Hormones and
• Pituitary Function

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Introduction

• Feeling a little frisky ?
• Does your heart pound when things go bump in the
  night?
• Do you rub cortisone cream on skin rashes?
• Women What regulates your menstrual cycle? Are
  you pregnant?
• Men Why are you so hairy?
• The answer to all these questions can be answered
  by the study of hormones !!!

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• Objectives
• Define each of the key terms
• List the hormones secreted by the anterior and
  posterior pituitary gland
• List the hormones secreted by the hypothlamus
  gland

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Key Terms

• Adrenocorticotropin ( ACTH )
• Anterior pituitary gland
• Posterior pituitary gland
• Follicle Stimulating Hormone ( FSH )
• Negative Feedback
• Positive Feedback
• Hypothalamus gland
• Releasing Hormone
• Tropic hormone
• Effector hormone
• TSH
• GH
• LH

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Endocrine glands
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• Introduction to Hormones
• Hormones are chemical signals produced by
  endocrine glands
• Hormones are secreted into the plasma where they
  travel to and cause changes in the activities of
  target tissues
• The target tissue is physically disconnected
  from the endocrine gland
• Target tissues have specific membrane receptor
  sites that interact with their respective
  hormones
• The metabolic activity of the target tissue is
  modified by the hormone
• Other endocrine glands can themselves be target
  tissues
• Multiple hormones may interact to regulate one
  physiological activity
• A single hormone can effect more than one target
  tissue

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• Classifications of hormones
• Steroids
• Polypeptides ( proteins )
• Amines
• Steroid characteristics
• Cholesterol derivative ( water insoluble
  requires carrier molecule )
• Penetrates target cell and stimulates protein
  synthesis
• Long half-life ( 60 100 minutes )
• Not stored - Synthesized and released
• Examples
• Adrenal glands Aldosterone , Cortisol
• Ovaries / Testes Estrogens , Testosterone

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Examples of Steroid Hormones
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• Protein characteristics
• Water soluble ( dont require carriers )
• Short half-life ( 5 60 minutes )
• Stored in cells
• Cannot cross cell membrane ( receptor
  interactions)
• Examples
• Pituitary FSH, LD, TSH, HCG
• Amine characteristics
• Synthesized from amino acids
• Cannot cross target cell membrane ( receptor
  interactions )
• Examples
• Thyroid T3 , T4
• Adrenal Epinephrine

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• Mechanisms of control
• Plasma hormone concentrations are regulated by
  altering the rate of hormone synthesis by the
  endocrine glands
• Tropic hormones
• Hormones that regulate other endocrine glands
• Positive feedback
• ? substance X ?
  hormone Y
• Example ? Glucose ?
  insulin hormone
• Negative feedback
• ? substance W ?
  hormone Z
• Example ? Calcium ? PTH
  hormone

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• Indirect Control mechanisms
• Tropic Hormone effects other endocrine gland
• Effector Hormone effects a non-endocrine tissue
• A type of negative feedback
• ? effector hormone causes decreased tropic
  hormone
• Example

Cortisol ( Tropic hormone from the adrenal
gland) Pituitary gland secrets ACTH
( Effector hormone ) ? ACTH decreases
cortisol
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• Methodologies for measuring hormones
• Early methodologies involved studying the effects
  of hormones on test animal tissues
• Famous example The Rabbit Test for pregnancy
  
• Pregnant women synthesize the hormone HCG
• Urine from pregnant women was injected into
  rabbits
• HCG ( if present ) altered the rabbits
  reproductive organs
• But the rabbit had to be dissected to examine the
  ovaries
• Actually, the rabbit always died !!!
• Crude techniques such as this were necessary
  because plasma hormone concentrations were
  extremely small Too small for routine
  colorimetric techniques

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• Hormone Methodologies
• Competitive Immunoassays ( Antibody )
• EIA, FIA, RIA
• ELISA
• Fluorescent Polarization
• Competitive Protein Binding ( Transport proteins
  )
• Receptor Assays ( Hormone receptors )
• Traditional spectrophotometric techniques are not
  used because they are insensitive to the very low
  concentrations of plasma hormones

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• Hypothalamus Gland
• The master endocrine gland
• Links the central nervous system ( CNS ) to the
  endocrine system
• The CNS stimulates the hypothalamus to secrete a
  variety of Releasing Hormones that affect the
  Anterior Pituitary Gland
• Releasing hormones are not found in the plasma
  They are secreted directly into the anterior
  pituitary
• The anterior pituitary responds by secreting many
  different hormones
• Hypothalamus disorders can only be detected via
  their effects of the anterior pituitary (
  releasing hormones arent in the plasma )

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• Anterior pituitary
• Stimulated by the hypothalamus releasing
  hormones
• Releasing hormones delivered directly at the
  pituitary via the pituitary stalk ( not via the
  blood )
• Hormones synthesized by the anterior pituitary
• LH Lutenizing hormone
• FSH Follicle Stimulating hormone
• TSH Thyroid Stimulating hormone
• ACTH Adrenocorticotropin
• GH Growth Hormone

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HYPOTHALAMUS GLAND
Releasing hormone
CRH
TRH
GHRH
ACTH
GnRH
TSH
LH FSH
GROWTH HORMONE
THYROID GLAND
OVARIES TESTES
ADRENAL GLAND
TISSUE BONE
TSH, LH, FSH, GH and ACTH are all secreted by
the anterior pituitary
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• Posterior pituitary
• Releases Antidiuretic Hormone ( ADH
  Vasopressin ) that was synthesized in the
  hypothalamus gland

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Links
http//www.endocrineweb.com http//training.seer.
cancer.gov/module_anatomy/unit6_3_endo_glnds.html
http//www.gen.umn.edu/faculty_staff/jensen/1135/
webanatomy/wa_ endocrine/wa_endo_glands_1.html