7.2 The Classification of Hormones Flashcards
How can hormones be classified?
by their source, how they are controlled in the brain, the type of receptor they bind to or chemical class.
what are the three main chemical classes of hormones?
Peptide/protein hormones, steroid hormones, and amino acid–derived (amine) hormones.
what are peptide/protein hormones made of, and what is their diversity like?
Hormones composed of linked amino acids. They can range from small peptides to large proteins and glycoproteins.
What is post-translational modification of prohormones?
The process where prohormones are cleaved into active hormones and other peptide fragments
How are peptide hormones synthesized and released?
They are synthesized as preprohormones, processed to prohormones in the ER, and then converted to active hormones in the Golgi. They are stored in vesicles and released by exocytosis.
How do peptide hormones typically act on target cells?
They bind to surface membrane receptors and use signal transduction systems to initiate responses.
What is unique about steroid hormones compared to peptide hormones (what are they derived from, what are they, what do they diffuse across, what manner are they synthesized and released)?
Steroid hormones are derived from cholesterol, are lipophilic, and diffuse across membranes. They are synthesized and released as needed, not stored.
what do steroid hormones bind to when being transported in the blood and why?
They are bound to protein carriers because they are not very soluble in plasma. The carrier protects them and extends their half-life.
What are the main actions of steroid hormones at the cellular level (what do they bind, what do they act as and why)?
They bind to intracellular receptors and act as transcription factors to regulate gene expression.
What are amino acid–derived (amine) hormones, what amino acids are they derived from?
Hormones derived from single amino acids, either tryptophan (e.g., melatonin) or tyrosine (e.g., catecholamines and thyroid hormones).
How do catecholamines and thyroid hormones differ despite both being derived from tyrosine (what types of receptors do they bind to)?
Catecholamines bind to cell membrane receptors like peptide hormones, while thyroid hormones have intracellular receptors and act like steroid hormones.
