Chemical Coordination and Integration

Mechanism of hormone action (elementary idea)

  • Protein hormones bind to the G-Protein coupled receptor (GPCR) that is present on the cell membrane, that activates Adenylate cyclase (AC) to convert ATP into cyclic Amp (CAMP), called as secondary messenger.
  • CAMP further activates protein kinases (PK) to induce a cascade of reactions which stimulates a biochemical and physiological reaction to an organ.
  • Steroid hormones have their receptors in the cytosol, as these hormones easily dissolve in the cell membrane.
  • The receptors along with the hormones activate the gene of the DNA from which the protein produced, activates the physiological function of the organ.
  • There is no secondary messenger production in steroidal hormone activation.
  • Hormones – Classification :
  • Amine hormones are derived from tyrosine amino acid
    Eg : Thyroxine (T4), Adrenalin and nor – adrenaline.
  • Steroidal hormones are fat soluble.
    Eg : Hormones of Gonads and Adrenal cortex.
  • Proteinaceous hormones are water soluble
    Eg :TSH, FSH, LH
  • Long peptides are insulin, glucagon, ACTH and collips hormone
  • Short peptides are oxytocin, Vasopressin (ADH) and mSH.

Watch this video for the topic from 21:40 to 36:26

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