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Questions and Answers
Which enzyme converts norepinephrine to normetanephrine?
What is the primary way catecholamines increase blood glucose levels?
Which of the following is NOT a function of catecholamines?
How are the metabolic products VMA and Homovanillic Acid excreted?
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What is the primary role of catecholamines in regulating heart activity?
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Why do catecholamines have a short plasma half-life?
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Study Notes
Functions of Catecholamines
- Catecholamines, especially norepinephrine and epinephrine, contribute to the metabolic response to trauma.
- They provide fatty acids as an energy source by stimulating lipolysis.
- They increase glucose production, a vital energy source for the brain, by: • Stimulating glycogenolysis and gluconeogenesis. • Inhibiting insulin secretion. • Stimulating glucagon secretion.
- They regulate blood pressure by causing vasoconstriction.
- They affect heart activity, increasing cardiac output.
- They reduce hypersensitivity reactions.
- They increase heat production.
Transport of Catecholamines
- Catecholamines are hydrophilic, so they are not bound to carrier proteins in plasma.
- As a result, they have a short plasma half-life of 10-30 seconds.
Metabolism of Catecholamines
- The liver metabolizes catecholamines through complex pathways.
- Norepinephrine and epinephrine are converted into normetanephrine and metanephrine, respectively, ultimately forming Vanillyl Mandelic Acid (VMA).
- Dopamine is converted into Homovanillic Acid.
- VMA and Homovanillic Acid are conjugated with glucuronate or sulfate in the liver.
- These conjugated metabolites are primarily excreted in the urine and, to a lesser extent, in the feces.
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Description
Learn about the roles of catecholamines, specifically norepinephrine and epinephrine, in metabolism. This quiz covers their functions in responding to trauma, energy production, and glucose regulation.
