Term
| Describe the four different chemical classifications of hormones discussed in class. |
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Definition
1. Amine ligands - derived from tyrosine or tryptophan (include norepinephrine, epinephrine, thyroxine, melatonin)
2. Polypeptide/protien ligands - chains of amino acids (iinclude ADH, GH, insulin, oxytocn, glucagon, ACTH, PTH)
3. Glycoproteins - protein + carbohydrate group (include LH, FSH, TSH)
4. Steroids - lipids derived from cholesterol (include testosterone, estrogen, progesterone, and cortisol) |
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Term
| Differentiate between the solubility classifications of hormones. |
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Definition
Hydrophilic hormones (most amino acid based peptides/proteins) are soluble in water and insoluble in lipids.
Lipophilic hormones (steroids and thyroxine) are insoluble in water and soluble in lipids. |
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Term
| Indicate where hydrophilic/lipophilic hormones are synthesized. |
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Definition
Hydrophilic hormones are synthesized by the rough ER and modified in the Golgi Bodies. There must be a need for synthesis, and they are similar to other proteins in the cell. They are finally stored in vesicles for exocytosis.
Lipophilic hormones typically derive from a cholesterol precursor, via enzymatic modification. Their secretion depends upon their synthesis. Only cholesterol precursor is stored. And since they're soluble (and thus permeable to the plasma membrane) they go right through into the bloodstream. |
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Term
| Indicate how hydrophilic/lipophilic hormones are transported in the blood. |
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Definition
Hydrophilic hormones readily dissolve in the plasma. They meet their receptors on the surface of the outer membrane for their target cells.
Lipophilic hormones cannot dissolve in plasma, so they must travel bound to protein. The protein must unbind in order for the hormone to have any action. Since they are soluble in lipids (and thus the plasma membrane), they need no recepters; they just permeate the membrane of their target cell. |
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Term
| Where are the receptors for hydrophilic/lipophilic hormones. |
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Definition
Hydrophilic hormones bind to their recepters on the surface of the outer plasma membrane of their target cells.
Lipophilic hormones can easily pass through the plasma membrane, so they bind with receptors inside the cell (cytosol and nucleus). |
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Term
| What is the general effect of hydrophilic/lipophilic hormones after the hormones bind to their receptors? |
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Definition
Hydrophilic hormones generally alter membrane ion permeability by opening and closing channcels. They also may activate a messenger system, which alters the protein activiity within the cell, to elicit a specific response.
Lipophilic hormones contribute to gene activation for protein synthesis. |
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Term
| Which type of hormone (hydrophilic/lipophilic) can be stored in a cell for release at a later time? Which cannot be stored? |
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Definition
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Term
| What is the purpose of a secondary messenger system? |
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Definition
| The purpose of a secondary messenger system (cascading effect) is to amplify the original signal. |
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Term
| What is the effector enzyme for the secondary messenger system discussed in class? |
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Definition
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Term
| What is the actual second messenger of the secondary messenger system discussed in class? |
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Definition
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