Hormones: Practice Questions

A hormone is a chemical secreted by a cell or group of cells into the blood for transport to a distant target, where it is effective at very low concentrations.

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Hormones can control the rates of enzymatic reactions, control the transport of ions or molecules across cell membranes, or control gene expression and protein synthesis.

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Hormones bind to target cell receptors and initiate biochemical responses.

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The three main chemical classes of hormones are peptide/protein hormones, steroid hormones, and amino acid-derived (amine) hormones.

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Peptide hormones are synthesized as preprohormones on ribosomes, converted to prohormones in the ER, processed in the Golgi complex, and released into the extracellular space through secretory vesicles. They are then transported in the bloodstream to their target cells.

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Peptide hormones are lipophobic and bind to surface membrane receptors on target cells. They initiate a cellular response through a signal transduction system.

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Insulin is an example of a peptide hormone.

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Steroid hormones are derived from cholesterol.

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