Podcast
Questions and Answers
Which hormones are stored in secretory granules and released by exocytosis?
Which hormones are stored in secretory granules and released by exocytosis?
- Aldosterone and cortisol
- Catecholamines and polypeptide hormones (correct)
- Thyroid hormones and steroid hormones
- Insulin and glucagon
In which form do steroid and thyroid hormones leave the cell?
In which form do steroid and thyroid hormones leave the cell?
- Attached to receptor proteins
- Stored in secretory granules
- Free form within the cytoplasm (correct)
- Bound to transport proteins
What is the role of transport proteins in hormone circulation?
What is the role of transport proteins in hormone circulation?
- To act as hormone receptors
- To carry hormones in a free form
- To facilitate hormone synthesis
- To bind and transport hormones in the blood (correct)
Which hormone has a longer plasma half-life, thyroxin or aldosterone?
Which hormone has a longer plasma half-life, thyroxin or aldosterone?
What factor is the plasma half-life of a hormone correlated with?
What factor is the plasma half-life of a hormone correlated with?
Which hormones circulate in a free form rather than bound to transport proteins?
Which hormones circulate in a free form rather than bound to transport proteins?
Where are catecholamines and polypeptide hormones typically stored?
Where are catecholamines and polypeptide hormones typically stored?
Which type of hormones are readily passed into the cell due to being hydrophobic?
Which type of hormones are readily passed into the cell due to being hydrophobic?
What is the function of the receptor site on a cell?
What is the function of the receptor site on a cell?
How are peptide hormones primarily synthesized?
How are peptide hormones primarily synthesized?
Which group of cells responds to specific hormones?
Which group of cells responds to specific hormones?
What triggers the responses of target cells after a G protein signaling cascade?
What triggers the responses of target cells after a G protein signaling cascade?
How do protein hormones initiate a response in target cells?
How do protein hormones initiate a response in target cells?
Which type of hormone is known to penetrate the cell and bind to intracellular receptors?
Which type of hormone is known to penetrate the cell and bind to intracellular receptors?
How do water-soluble hormones primarily travel in the bloodstream?
How do water-soluble hormones primarily travel in the bloodstream?
What is the role of a transcription factor activated by a hormone?
What is the role of a transcription factor activated by a hormone?
Which type of hormone affects the permeability of the cell membrane by opening or closing ion channels?
Which type of hormone affects the permeability of the cell membrane by opening or closing ion channels?
How do lipid hormones primarily travel in the bloodstream?
How do lipid hormones primarily travel in the bloodstream?
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Study Notes
G Protein Signaling Mechanism
- Hormone binds to receptor, activating G protein (Gs)
- G protein activates adenylate cyclase, converting ATP to cAMP (2nd messenger)
- cAMP activates protein kinases, triggering responses of target cell (activates enzymes, stimulates cellular secretion, opens ion channels, etc.)
Steroid Hormones
- Hydrophobic, readily pass into cell
- Bind receptor associated with DNA, causing gene to be transcribed
- Specific protein produced alters metabolism in various ways
Hormone Receptors and Effects
- Receptor site: location on a cell where hormone binds (lock)
- Target tissues: group of cells that respond to specific hormones
- Specificity: specific hormones bind to specific receptor sites
Synthesis and Storage of Hormones
- Amino acid and steroid hormones are synthesized through series of enzymatic reactions
- Peptide hormones are synthesized as proteins in the ribosomes
- Catecholamines and polypeptide hormones are stored in secretory granules
- Thyroxin and steroid hormones are not stored in granules and are present in the free form within the cytoplasm
Hormone Release
- Catecholamine and polypeptide hormones are released by exocytosis
- Thyroxin and steroid hormones leave the cell by simple transfer through the plasma membrane
Hormone Transport
- Released hormones enter the blood, where they may circulate in two forms: free (unbound) and bound
- Free hormones bind to receptor, while bound hormones are carried by specific albumins and globulins synthesized in the liver
- Steroid and thyroid hormones are bound to transport proteins, whereas polypeptide and other amine hormones circulate in a free form
Types of Hormones and Mechanism of Chemical Signaling
- Protein hormones: bind to receptor protein on the surface of the target cell, triggering signal transduction pathway
- Steroid hormones: penetrate the cell and bind to receptor protein inside the target cell, triggering signal transduction pathway
- Hormones can cause change by altering cell activity, changing permeability of cell membrane, and synthesizing proteins
Regulation of Hormones
- Blood levels of chemicals (e.g. blood glucose levels)
- Other hormones (e.g. TSH signals thyroid gland to release thyroid hormone)
- Nervous system
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