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Questions and Answers
What is the primary method by which hormones travel to their target sites?
What type of hormones utilize the fixed membrane receptor mechanism?
What is the primary mode of transportation for hormones to reach their target sites?
Which hormone is primarily responsible for regulating growth and controlling the functioning of endocrine glands?
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Which enzyme is activated when a hormone binds to its specific target receptor in the cell membrane during the fixed membrane receptor mechanism?
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What characteristic do all peptide hormones share?
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What is the primary function of the parathormone secreted by the parathyroid gland?
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What characteristic allows lipid hormones to pass through the plasma membrane?
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Which hormones are derived from aromatic amino acids?
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What acts as the secondary messenger in the fixed membrane receptor mechanism?
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Which tissue in the human body is targeted by retinoid hormones for their regulatory functions?
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What are steroid hormones derived from?
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What enzyme deactivates cAMP in the fixed membrane receptor mechanism?
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Which of the following is an example of a peptide hormone?
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Excessive amounts of which vitamin can cause birth defects, urging caution in its use during pregnancy?
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Which of these is a feature of peptide hormones?
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What type of hormone includes compounds derived from fatty acids that compose the plasma membrane?
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What effect does cAMP have within the cell during the fixed membrane receptor mechanism?
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What type of hormone is insulin?
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What is the function of calcitriol in calcium homeostasis?
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Which hormone type contains carbohydrate side chains?
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Which of the following hormones is an example of a lipid hormone?
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What component is essential for receptor stimulation in a target cell?
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Which class of hormones can cross the plasma membrane due to their solubility?
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Lipid and phospholipid-derived hormones are produced from which of the following?
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Steroid hormones, such as testosterone, are primarily derived from which substance?
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Which monoamine hormone is derived from tryptophan and regulates sleep patterns?
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How many iodine atoms are incorporated into thyroid hormones?
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Which of the following is an example of an endocrine hormone?
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Hormones that diffuse to neighboring target cells are classified as which type?
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What allows cells to respond to very low concentrations of hormone?
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Which statement about hormone action specificity is correct?
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What type of molecules utilize the mobile receptor mechanism to initiate biochemical changes in the cell?
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Where do lipid-soluble hormones bind after diffusing through the plasma membrane?
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What is the result of the receptor-hormone complex formation inside the cell?
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Which process follows the transcription of DNA initiated by the hormone-receptor complex?
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What is the final outcome of the mobile receptor mechanism on cell activity?
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Which cellular component is primarily involved in the translation of mRNA into protein during the mobile receptor mechanism?
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What activates the enzyme adenyl cyclase in the fixed membrane receptor mechanism?
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What acts as the secondary messenger in the fixed membrane receptor mechanism?
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Where is the receptor located in the mobile receptor mechanism?
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What is the final result of the mobile receptor mechanism?
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Which type of hormones utilize the mobile receptor mechanism?
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What is the role of phosphodiesterase in the fixed membrane receptor mechanism?
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Which step involves the conversion of ATP to cAMP in the fixed membrane receptor mechanism?
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In the mobile receptor mechanism, the hormone-receptor complex binds to what in the nucleus?
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Study Notes
Chemistry of Hormones
- Hormones are chemical messengers released by cells or glands that affect cells in other parts of the body.
- Hormones are released into the bloodstream and travel to target sites.
- The target cell has specific receptors for a given hormone, which triggers a change in cell activity.
- Receptor stimulation may send feedback to the original hormone-producing cell.
Types of Hormones
- There are three classes of hormones: peptide hormones, lipid hormones, and monoamine hormones.
Peptide Hormones
- Consist of short or long chains of amino acids.
- Examples include vasopressin, insulin, and follicle-stimulating hormone.
- Are water-soluble and cannot pass through the plasma membrane alone.
Lipid Hormones
- Include steroid and eicosanoid hormones.
- Are lipid-soluble and can pass through the plasma membrane.
- Steroid hormones are derived from cholesterol and eicosanoid hormones from fatty acids.
Monoamines
- Are derived from aromatic amino acids like phenylalanine, tyrosine, and tryptophan.
Mechanism of Hormone Action
- The mechanism of hormone action is grouped into two classes:
- Fixed membrane receptor mechanism
- Mobile receptor mechanism
Fixed Membrane Receptor Mechanism
- Shown by water-soluble hormones that are amines or proteins in composition (e.g., growth hormone, oxytocin, ADH).
- Hormones cannot pass through the lipid membrane.
- Hormones bind to target receptors on the cell membrane, activating adenyl cyclase.
- cAMP acts as a secondary messenger, diffusing through the cell membrane and activating enzymatic reactions.
- cAMP is deactivated by phosphodiesterase.
Mobile Receptor Mechanism
- Shown by lipid-soluble hormones that are steroids or thyroid hormones (e.g., testosterone, estradiol, aldosterone).
- Hormones can easily pass through the lipid membrane.
- Hormones bind to receptors present inside the cytoplasm.
- The hormone-receptor complex enters the nucleus and binds to specific DNA sequences, leading to gene activation and protein synthesis.
- Newly synthesized proteins change cell activity.
Classification of Hormones
- Endocrine hormones are released into the blood and carried to target cells throughout the body (e.g., insulin and glucagon).
- Paracrine hormones are released into the extracellular space and diffuse to neighboring target cells (e.g., eicosanoid hormones).
- Autocrine hormones affect the same cell that releases them, binding to receptors on the cell surface.
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Description
Learn about the chemistry of hormones, how they are released and travel through the bloodstream, and how they interact with target cells to affect cellular activity.
