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Questions and Answers
What is the primary function of hormones in the body?
What is the primary function of hormones in the body?
How are hormones transported to other parts of the body?
How are hormones transported to other parts of the body?
What is the characteristic of hormones that makes them stimulatory?
What is the characteristic of hormones that makes them stimulatory?
What is the main difference between cell surface receptors and intracellular receptors?
What is the main difference between cell surface receptors and intracellular receptors?
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What happens when a water-soluble hormone binds to a cell-surface receptor?
What happens when a water-soluble hormone binds to a cell-surface receptor?
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What is the outcome of hormone binding to a target cell receptor?
What is the outcome of hormone binding to a target cell receptor?
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What is the term for cells that contain specific receptors for a particular hormone?
What is the term for cells that contain specific receptors for a particular hormone?
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How do intracellular receptors alter gene expression?
How do intracellular receptors alter gene expression?
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Where are the receptors for lipid-soluble hormones typically located?
Where are the receptors for lipid-soluble hormones typically located?
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What is the result of the binding of the hormone-receptor complex to specific DNA binding sites?
What is the result of the binding of the hormone-receptor complex to specific DNA binding sites?
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What is the purpose of regulating hormone secretion?
What is the purpose of regulating hormone secretion?
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What type of feedback mechanism amplifies physiological changes?
What type of feedback mechanism amplifies physiological changes?
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How do lipid-soluble hormones compare to water-soluble hormones in terms of onset of action?
How do lipid-soluble hormones compare to water-soluble hormones in terms of onset of action?
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What happens to hormones in the process of hormone clearance?
What happens to hormones in the process of hormone clearance?
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Study Notes
Hormones: Biosynthesis, Metabolism, and Mechanism of Action
What are Hormones?
- Hormones are chemical messengers produced by endocrine glands and secreted into the bloodstream to coordinate certain body functions.
Classes of Hormones
- Hormones can be classified based on their solubility and chemical structure.
Target Cells
- Target cells contain specific receptors (binding site) for a particular hormone.
Hormone Receptors
- There are two types of hormone receptors: cell surface receptors and intracellular receptors.
- Cell surface receptors are located on the plasma membrane and generate second messengers that alter the activity of other molecules within the cell.
- Intracellular receptors are located in the cytoplasm or nucleus and alter transcriptional activity of responsive genes.
Hormones with Cell Membrane Receptors
- Water-soluble hormones have a hormone-binding site located on the external portion of a specific cell-surface receptor.
- Hormones exert their action by binding to target cell receptor proteins, leading to a signal that is conveyed to the interior of the cell.
- Amplification of hormone activity is achieved by activation of a cascade of chemical reactions.
Hormones with Intracellular Receptors
- Lipid-soluble (steroid) hormones diffuse easily through the lipid bilayer of cell membranes and bind to receptors in the cytoplasm or nucleus.
- Binding causes a change in affinity of the receptor for binding sites on DNA in the cell nucleus, leading to changes in gene expression.
- Onset of action of lipid-soluble hormones is slow compared to water-soluble hormones, and there is no amplification cascade.
Regulation of Hormone Secretion
- Three types of stimuli stimulate the synthesis and release of hormones.
- Regulation of hormone secretion normally maintains homeostasis and prevents overproduction or underproduction of a particular hormone.
- Negative feedback is the most common mechanism, which reverses the direction of a change in a physiological system.
- Positive feedback amplifies physiological changes, leading to more hormone release.
Hormone Clearance
- Hormones are cleared from the plasma in several ways.
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Description
This quiz covers the biosynthesis, metabolism, and mechanism of action of hormones, including their classification, production, and function in the human body.
