Types of Hormones

There are many types of hormones in the human body. However, they all can be divided into three classes. This categorization based on their chemical structure.

Types of Hormones:

  • lipid-derived
  • amino acid-derived
  • peptide hormones (which includes peptides and proteins).

One of the features of lipid-derived hormones is that they can diffuse across plasma membranes whereas the amino acid-derived and peptide hormones cannot.

Exocrine hormones are secreted through a duct into the bloodstream. They will usually effect a distant organ or tissue.

Endocrine hormones are secreted from the tissue instead of through a duct. They enter the bloodstream via capillaries.

Hormones of the body and how they work

Lipid Derived Steroid Hormones

Steroid hormones: water balance, sexual development and stress response. Most are derived from cholesterol.
  • Androgens, estrogens and progesterone
  • Mineralocoritcosteriods and gluccorticosteriods
  • Steroid hormones are insoluble in water
  • Steroid hormones are carried by transport proteins in blood.
  • They remain in circulation far longer than peptide hormones.

Amino Acid Derived Hormones

Water-soluble and insoluble in lipids. These hormones cannot pass through plasma membranes of cells.

Commonly derived from tyrosine and tryptophan.

  • Thyroid hormone regulates the development of organs and metabolism.
  • Catecholamines are considered stress hormones and neurotransmitters.
  • Tryptophan is a precursor to serotonin and melatonin
  • Serotonin is found in our GI tract and regulates movement in our intestines.
  • Serotonin is associated with mood, appetite and wellbeing.

Peptide Hormones

Hormones derived from peptides. Polypeptide chain (chain of amino acids). Includes molecules that are short polypeptide chains and includes small proteins ie) growth hormones produced by the pituitary .
  • Secreted peptides are stored within the vesicles in the cells.
  • Secreted peptides are released in response to stimuli.
  • Water-soluble and insoluble in lipids.
  • These hormones cannot pass through plasma membranes of cells.
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