AP Notes, Outlines, Study Guides, Vocabulary, Practice Exams and more!

Hormones

hormone - regulatory chemical secreted by endocrine gland 

  • only target cell can respond to hormone (but blood carries hormone throughout the body)
  • neurotransmitter - only diffuse a short distance, but may be chemically similar to hormones
    • effects the postsynaptic neuron
    • neurohormone - chemicals secreted from neurons into blood
    • some molecules work as both neurotransmitters and hormones
  • targets ligand-gated receptors on target cells
    • messages sometimes relayed through 2nd messenger, magnified through enzyme cascade
  • paracrine regulation - using chemicals as local regulators in an organ
  • pheromone - chemical released into the environment
    • used as communication between animals

types of hormones - 

  • polypeptides - chains of amino acids (never more than 100)
    • insulin, ADH
  • glycoproteins - polypeptides (w/ over 100 amino acids) attached to carbohydrate
    • FSH, LH
  • amines - derived from tyrosine/tryptophan amino acids
    • catecholamines - secreted by adrenal medulla, includes adrenaline/noradrenaline
    • melatonin, thyroid hormone
  • steroids - lipids derived form cholesterol
    • sex steroids - secreted by testes, ovaries, placenta, adrenal cortex
    • corticosteroids - secreted only by adrenal gland
  • lilophilic hormones - fat soluble, includes steroids/thyroxine
  • lilophobic hormones - water soluble, all other hormones
  • most releases of hormones controlled by the brain

hormones that enter cells - lipophilic hormones easily enter cells (can pass plasma membrane) 

  • either finds receptor in cytoplasm or inside nucleus (either way, eventually reaches nucleus)
  • hormone response elements - DNA segments binding to hormones

hormones that do not enter cells - lipophobic hormones can’t pass plasma membrane 

  • have to bind to receptors
  • 2nd messenger needed within the cell to get the reactions started
Subject: 
Biology
Subject X2: 
Biology

Need Help?

We hope your visit has been a productive one. If you're having any problems, or would like to give some feedback, we'd love to hear from you.

For general help, questions, and suggestions, try our dedicated support forums.

If you need to contact the Course-Notes.Org web experience team, please use our contact form.

Need Notes?

While we strive to provide the most comprehensive notes for as many high school textbooks as possible, there are certainly going to be some that we miss. Drop us a note and let us know which textbooks you need. Be sure to include which edition of the textbook you are using! If we see enough demand, we'll do whatever we can to get those notes up on the site for you!