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Questions and Answers
Which molecule acts as a secondary messenger to carry out cellular functions?
Which of the following molecules is not classified as a steroid hormone?
Which of the following is primarily involved in regulating metabolic processes in the body?
What is the primary function of vitamin D (cholecalciferol) in the body?
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Which of the following hormones are classified as steroid hormones?
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What determines whether a cell will respond to a hormone?
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Which of the following best describes target cells?
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How do hormones typically exert their effects on target cells?
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Which statement is true regarding hormone circulation?
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What is NOT a characteristic of a hormone's action on target cells?
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What is one of the primary roles of insulin in the body?
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Where are insulin receptors primarily located?
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How does insulin affect glucose production in the liver?
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Which of the following statements about insulin is correct?
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What is the primary effect of insulin on muscle cells?
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What characteristic distinguishes cholesterol-derived substances in their cellular interaction?
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What is a potential effect when a molecule binds to a receptor inside the cell?
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What is the likely outcome when a substance binds to receptors on the cell surface?
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Which characteristic is associated with soluble substances derived from cholesterol?
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What is the primary mechanism through which most hormones exert their effects on target cells?
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Study Notes
Intracellular Hormone Receptors and Activation of Genes
- Steroid hormones and thyroid hormones (e.g., testosterone, estrogen, T3, T4) can easily enter target cells.
- Inside the cell, they bind to and activate specific intracellular receptors.
- The hormone-receptor complex then travels to the nucleus to regulate gene activity.
- This regulation influences functions like growth, metabolism, and reproduction.
Hormone Action and Target Cells
- Hormones circulate throughout the body, but only activate specific cells known as target cells.
- G proteins trigger the release of second messengers (e.g., cAMP) within target cells.
- These second messengers initiate chain reactions, leading to cellular responses such as activating protein kinases.
Insulin's Effects on Glucose Uptake
- Insulin increases glucose uptake into cells.
Example: Steroid Hormones
- Steroid hormones (like testosterone and estrogen) can act as secondary messengers to carry out cellular functions.
Negative Feedback Loops
- High levels of cortisol in the blood suppress the release of corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH), which in turn reduces cortisol production.
- This mechanism helps maintain hormone balance.
Hormone Receptors
- Hormone receptors are proteins that bind to hormones, triggering a cellular response
- Some hormone receptors are located on the cell surface while others are found inside the cell
- Insulin receptors are found on the surface of muscle cells and liver cells
- Thyroid hormone receptors are found in the nucleus
G Protein-Linked Hormone Receptors
- G protein-linked hormone receptors are characterized by their use of a G protein as an intermediary
- The binding of a hormone to the receptor activates a G protein inside the cell
- The activated G protein triggers the production of cAMP, which acts as a second messenger
- The cAMP cascade leads to a series of intracellular events, ultimately resulting in a cellular response
- Examples of hormones that utilize this mechanism include adrenaline and glucagon
Enzyme-Linked Hormone Receptors
- Enzyme-linked hormone receptors are characterized by their direct enzymatic activity
- One example is the insulin receptor, which possesses tyrosine kinase activity
- When insulin binds to its receptor, the receptor's tyrosine kinase activity is activated, leading to the phosphorylation of intracellular proteins
- This phosphorylation cascade ultimately leads to the cellular response triggered by insulin, such as glucose uptake in muscle cells and inhibition of glucose production in the liver
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Description
Explore the mechanisms of intracellular hormone receptors and their role in gene activation. This quiz covers the actions of steroid hormones and thyroid hormones, the function of target cells, and the effects of insulin on glucose uptake. Test your knowledge on how hormones regulate vital cellular functions.
