Hormone Specificity


How do hormones only affect on organ if they are in the blood?  

see "Endocrine System" by Encyclopedia Britannica

 

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  1. Endocrine glands have a LOT of capillaries
  2. Capillaries carry hormones away from gland
    • capillary is place where material easily enters or leaves the blood since the wall of capillary is so thin
  3. Hormones leave hormone glands in the blood
  4. Blood - and hormones - travel throughout body and touch EVERY cell
  5. ...but hormones only affect target tissue
  6. Target tissue has receptor for hormones
    • every hormone is chemical with chemical shape (3D shape; specific charges)
    • receptors accept specific shape
    • one hormone fits into receptor 
    • every hormone requires a unique receptor
    • receptor receiving hormone "turns on" 
  7. Target activated by hormone