The Endocrine System

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The Endocrine System

• Although we rarely think about them, the glands
  of the endocrine system and the hormones they
  release affect almost every cell, organ, and
  function of our bodies.

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One of the Bodys Control Systems

• The endocrine system controls
• mood
• growth development
• tissue function
• metabolism (energy use)
• reproductive processes

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What Is the Endocrine System?

• The foundations of the endocrine system are the
  hormones and glands.

A hormone is a chemical released by a gland that
causes target cells to perform specific functions.
A gland is a tissue or organ that produces and
releases chemical substances.
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As the body's chemical messengers, hormones
transfer information and instructions from one
set of cells to another. Only endocrine glands
make hormones.

• Exocrine glands (pronounced ek-suh-krin), such
  as the sweat and salivary glands, release
  secretions in the skin or inside of the mouth.
  The chemicals stay in the area of the body where
  they were produced.

• Endocrine glands, on the other hand, release more
  than 20 major hormones directly into the
  bloodstream where they can be transported to
  cells in other parts of the body.

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Endocrine Glands

• The major glands that make up the human
  endocrine system are the
• Hypothalamus
• Pituitary
• Thyroid
• Parathyroids
• Adrenals
• Pancreas
• Ovaries and testes (reproductive glands)
• The pancreas also works with the digestive
  system.

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Hypothalamus

• a collection of specialized cells that is located
  in the lower central part of the brain
• the link between the endocrine and nervous
  systems
• controls the pituitary gland

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Pituitary

• Although it is no bigger than a pea, the
  pituitary gland, located at the base of the brain
  just beneath the hypothalamus, is considered the
  most important part of the endocrine system.
• It's often called the "master gland" because it
  makes hormones that control several other
  endocrine glands.
• The production and secretion of pituitary
  hormones can be influenced by factors such as
  emotions and seasonal changes.
• Among the hormones it produces is growth hormone,
  which stimulates the growth of bone and other
  body tissues.

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Thyroid

• located in the front part of the lower neck
• shaped like a bowtie or butterfly
• produces thyroid hormones, which control the
  rate at which cells burn fuels from food to
  produce energy
• Thyroid hormones also play a key role in bone
  growth and the development of the brain and
  nervous system.
• The production and release of thyroid hormones is
  controlled by the pituitary gland.

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Parathyroids

• four tiny glands
• attached to the thyroid
• function together
• help control the level of calcium in the blood
• The right amount of calcium is important for
  muscle function, including the heart muscle.

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AdrenalGlands

• The body has two triangular adrenal glands, one
  on top of each kidney.
• The adrenal glands have two parts, each of which
  produces a set of hormones and has a different
  function.
• The outer part produces hormones that regulate
  salt and water balance in the body, among other
  things.
• The inner part produces adrenaline, which
  increases blood pressure and heart rate when the
  body experiences stress.

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Pancreas

• The pancreas produces important hormones (insulin
  is one) that work together to maintain a steady
  level of glucose, or sugar, in the blood and to
  keep the body supplied with fuel.

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What Does the Endocrine System Do?

• Once a hormone is secreted, it travels from the
  endocrine gland through the bloodstream to the
  cells designed to receive its message. These
  cells are called target cells. When the hormone
  reaches its target cell, it locks onto the cell's
  surface and gives chemical instructions to the
  inner workings of the cell.

TARGET CELL ?
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Things That Can Go Wrong With the Endocrine System

• Too much or too little of any hormone can be
  harmful to the body.
• For example, if the pituitary gland produces too
  much growth hormone, a child may grow excessively
  tall. If it produces too little, a child may be
  abnormally short.
• Medicines that control the production of hormones
  or replace missing hormones can treat many
  endocrine diseases.

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INFORMATION SOURCEhttp//kidshealth.org
Homework Read pp. D24-D26 in science textbook.

• Updated and reviewed by
• Wayne Ho, MD, and Steven Dowshen, MDJanuary
  2004Edited and adapted by Beth Reopelle 2006