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The Endocrine System

The Endocrine System. Communication throughout the body. What is the endocrine System? . It is one of the 2 regulatory systems in the human body It is made up of endocrine glands that secrete chemical messengers called hormones

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The Endocrine System

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  1. The Endocrine System Communication throughout the body

  2. What is the endocrine System? • It is one of the 2 regulatory systems in the human body • It is made up of endocrine glands that secrete chemical messengers called hormones • Hormones travel through the blood allowing communication through all parts of the body

  3. Jobs of the Endocrine System • Regulation of metabolism and tissue maturation • Regulation of ion concentrations in the blood • Maintaining water balance • Helps control production of immune cells • Helps control heart rate and blood pressure

  4. . . . Still more! • Controls blood glucose and other nutrients • Controls reproductive functions • Regulates uterine contractions and milk production

  5. What is an endocrine gland? • They are ductless organs that secrete their hormones directly into the blood • Hormones cause a response in other cells, called target cells, but only if the other cells have receptors.

  6. Are there different types of hormones? • Yes! • There are two major categories: • Steroid hormones (lipid soluble) • Protein or peptide hormones (water soluble)

  7. Steroid Hormones • Can pass through the cell membrane • Have receptor molecules inside the cell • Usually take a longer period of time to act • Can be reproductive hormones • Can be taken orally because they will pass through the stomach walls

  8. Protein Hormones • Cannot cross the cell membranes • Need receptor molecules on the outside of target cells • Usually act very quickly • Cannot be taken orally because they cannot pass through the stomach wall and will be digested • A small amount can have a very big affect due to signal amplification

  9. How do Steroid Hormones Work? • 1. They pass through the cell membrane • 2. They bind a receptor in the cytoplasm of a target cell • 3. The receptor/Hormone complex enters the nucleus • 4. Gene expression is started and new gene products are formed

  10. How do Protein hormones work? • 1. The water-soluble hormone binds a receptor on the outside of the cell membrane • 2. A G protein activates an enzyme (adenylatecyclase) • 3. This causes a series of intracellular changes that can amplify the original signal • 4. Intracellular changes result in a change in productivity, enzyme activation, gene expression, cell shape, or cell motion

  11. How are Hormones controlled? • The Pituitary gland is the “master gland” that controls the endocrine system • The pituitary gland is controlled by its close neighbor, the hypothalamus (part of the nervous system)

  12. Two types of feedback: Negative: Positive: Used to break homeostasis Levels of hormones cause more hormone to be produced. Ex: Oxytocin in child birth causes stronger and stronger contractions • Used to maintain values in a normal range • Maintains homeostasis • Ex: Insulin and glucagon keep blood glucose levels constant

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