Human Endocrine System

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Human Endocrine System

• System of Hormone secreting Organs
• Some hormones only affect few tissues
• Others affect almost all body tissues
• Tropic Hormones target other endocrine glands

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Table of all Glands and their Hormones
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HYPOTHALMUS

• Integrates Endocrine and Nervous Systems
• Receives information from nerves all over body
• Releases endocrine signals appropriate to nerve
  inputs
• Secretions are stored in and regulate the
• Pituitary Gland

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PITUITARY GLAND

• Master Gland
• Hormones regulate other endocrine functions
• Two Distinct regions
• Anterior Pituitary
• Posterior Pituitary

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POSTERIOR PITUITARY GLAND

• Releases two hormones
• Oxytocin
• Induces uterus to contract during childbirth
• Releases milk during nursing
• Antidiuretic Hormone (ADH)
• Regulates osmolarity of blood
• Retention of water in kidneys

More on Posterior
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Figure 45.6a Hormones of the hypothalamus and
pituitary glands
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ANTERIOR PITUITARY GLAND

• Produces many hormones
• Growth Hormone (GH)
• Promotes growth in tissues
• Growth disorders result from abnormal GH
  production
• Overproduction GIGANTISM
• Underproduction - DWARFISM

More on Anterior
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ANTERIOR PITUITARY GLAND

• Follicle Stimulating Hormone (FSH)
• Stimulates activities in testes and ovaries
• Leutinizing Hormone (LH)
• Stimulates activities in testes and ovaries
• Thyroid Stimulating Hormone (TSH)
• Stimulates hormone production by thyroid
• Endorphins
• Hormones that inhibit the perception of pain
• Released when pain and stress reach certain level
• Growth Hormone (GH)
• Promotes growth in tissues
• Growth disorders result from abnormal GH
  production
• Overproduction GIGANTISM
• Underproduction - DWARFISM

More on Anterior
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Figure 45.6b Hormones of the hypothalamus and
pituitary glands
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PINEAL GLAND

• Small organ near center of brain
• Secretes the hormone
• MELATONIN affects skin pigments
• Most pineal functions related to biorythms
  associated with reproduction
• Biological Clock

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THYROID GLAND

• Two lobed organ located on the rear of trachea in
  throat
• Produces two similar hormones
• Triiodothyronine (T3) more active
• Thyroxine (T4)
• Critical in development and maturation
• Controls
• Blood Pressure
• Heart Rate
• Muscle Tone
• Digestion
• Reproduction
• Shortage of Thyroid hormone causing enlargment
• Goiter results from lack of iodine

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Figure 45.7 Two thyroid hormones
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Figure 45.8 Feedback control loops regulating
the secretion of thyroid hormones T3 and T4
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PARATHYROID GLAND

• Four glands embedded in the Thyroid Gland
• Secretes
• Parathyroid Hormone (PTH)
• Raises calcium ion levels in blood Ca 2
• Functions in processing of Vitamin D
• Works in conjunction with Thyroid and Calcitonin
  in Negative Feedback System

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Figure 45.9 Hormonal control of calcium
homeostasis in mammals
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PANCREAS

• These clusters of cells are found throughout the
  pancreas and secrete two major hormones
• Islets of Langerhans
• Alpha Cells
• Secrete GLUCAGON
• Beta Cells
• Secrete INSULIN
• Regulate the amount of GLUCOSE in blood
• Two types of Diabetes exist
• Type I
• Type II

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PANCREAS

• TYPE I Diabetes
• Autoimmune disorder.
• Usually appears in childhood.
• Treatment insulin injections.
• Type II diabetes mellitus (non-insulin-dependent
  diabetes)
• Usually due to target cells having a decreased
  responsiveness to insulin.
• Usually occurs after age 40 risk increases with
  age.
• Accounts for over 90 of diabetes cases.

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Figure 45.10 Glucose homeostasis maintained by
insulin and glucagon
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ADRENAL GLANDS

• Located adjacent to the kidneys
• 2 Regions
• Adrenal cortex - outer portion.
• Adrenal medulla - inner portion
• Adrenal Medulla reacts to stress and is closely
  related to Nervous System
• Adrenal Cortex also reacts to stress, but
  responds to endocrine signals

Adrenal Glands and Stress
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ADRENAL MEDULLA

• Secretes epinephrine or ADRENILINE and
  noradreniline
• Response to either positive or negative stress
• Responses include
• Pleasure
• Fear
• Danger
• Release of hormones directly into blood results
  in rapid bioenergetic boost

MORE
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ADRENAL MEDULLA

• Epinephrine and Noreinephrine
• Increase Glycogen breakdown in Liver and Skeletal
  Muscles
• Increase volume of Heartbeat
• Dilate bronchioles during breathing
• Epinephrine used in Asthma medications

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ADRENAL CORTEX

• Stress causes HYPOTHALAMUS to release hormone
  that stimulate Anterior Pituitary to release ACTH
• Raises blood Glucose levels
• Key Hormones include
• Corticosteroids
• Glucocorticoids
• Mineralocorticoids

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Figure 45.14 Stress and the adrenal gland
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TESTES

• Synthesize these hormones
• ANDROGENS
• Main hormone
• Testosterone
• Stimulate and maintain male reproductive system
  and sex characteristics
• Adrogens responsible for male development as
  fetus and secondary sex characteristics at
  puberty
• Hair Growth
• Low Voice

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OVARIES

• Synthesize these hormones
• ESTROGENS
• Similar role in maintaining female reproductive
  system and secondary sex characteristics
• Secretion regulated by FSH and LH

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Table 45.1 Major Vertebrate Endocrine Glands and
Some of Their Hormones (HypothalamusParathyroid
glands)
Second part of Table
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Table 45.1 Major Vertebrate Endocrine Glands and
Some of Their Hormones (PancreasThymus)
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Thymus

• Produces Thymosin which stimulates production of
  lymphocytes