Podcast
Questions and Answers
What type of hormones bind to receptors located on the cell membrane?
What type of hormones bind to receptors located on the cell membrane?
Which intracellular substance degrades cAMP, thus inactivating the response to a hormone?
Which intracellular substance degrades cAMP, thus inactivating the response to a hormone?
phosphodiesterase
Growth factor hormones, such as insulin, bind to which type of receptor?
Growth factor hormones, such as insulin, bind to which type of receptor?
tyrosine kinase receptors
Which is the correct order of events for hormones activating Gs proteins?
Which is the correct order of events for hormones activating Gs proteins?
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Which second messenger causes the release of calcium from the endoplasmic reticulum?
Which second messenger causes the release of calcium from the endoplasmic reticulum?
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Which of the following adrenergic receptors increase cAMP levels?
Which of the following adrenergic receptors increase cAMP levels?
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Which of the following hormones has intracellular receptors?
Which of the following hormones has intracellular receptors?
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What is the mechanism of action of lipid-soluble hormones?
What is the mechanism of action of lipid-soluble hormones?
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After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do?
After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do?
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Which hormone's receptor is always bound to DNA, even when the receptor is empty?
Which hormone's receptor is always bound to DNA, even when the receptor is empty?
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What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor?
What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor?
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What tropic hormone stimulates cortisol from the adrenal gland?
What tropic hormone stimulates cortisol from the adrenal gland?
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What is the function of the ventral hypothalamic neurons?
What is the function of the ventral hypothalamic neurons?
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Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones?
Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones?
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Which of the following hormones is regulated by a neuroendocrine ('letdown') reflex?
Which of the following hormones is regulated by a neuroendocrine ('letdown') reflex?
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Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized?
Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized?
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What is the most important regulatory factor controlling the circulating levels of thyroid hormone?
What is the most important regulatory factor controlling the circulating levels of thyroid hormone?
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Study Notes
Hormone Receptors and Mechanisms
- Water-soluble hormones, including insulin and epinephrine, bind to receptors on the cell membrane and cannot diffuse through the plasma membrane.
- Phosphodiesterase is an enzyme that breaks down cyclic AMP (cAMP), thereby inactivating hormone responses.
- Growth factor hormones, like insulin, associate with tyrosine kinase receptors, acting without a second messenger.
- The sequence for hormone activation of Gs proteins involves G protein activation, GTP binding, adenylate cyclase activation, and conversion of ATP to cAMP.
Second Messengers and Effects
- Inositol trisphosphate (IP3) functions as a second messenger that triggers the release of calcium from the endoplasmic reticulum.
- β adrenergic receptors are responsible for increasing cAMP levels through their coupling to adenylate cyclase via Gs proteins.
Lipid-Soluble Hormones
- Cortisol and thyroid hormones, both lipid-soluble, utilize intracellular receptors.
- The mechanism of action for lipid-soluble hormones involves gene activation that leads to increased protein synthesis.
- Once a lipid-soluble hormone binds to its receptor, the hormone-receptor complex acts as a transcription factor, engaging with DNA to activate specific genes.
Thyroid Hormones and Regulation
- Thyroid hormones maintain a constant binding to DNA, even in the absence of ligands, to ensure readiness for action.
- Chaperone proteins prevent intracellular receptors from binding to DNA until the hormone is attached, maintaining regulatory control.
- Adrenocorticotropic hormone (ACTH) stimulates cortisol production from the adrenal gland, with stress and ACTH acting as primary stimuli.
Hypothalamic Function and Growth Hormones
- Ventral hypothalamic neurons regulate thyroid-stimulating hormone (TSH) secretion through releasing and inhibiting hormones.
- Insulin-like growth factors (IGFs) are stimulated by growth hormone (GH) and are crucial for GH’s growth-promoting effects on bone and skin.
Neuroendocrine Reflex and ADH
- Oxytocin release is regulated by a neuroendocrine "letdown" reflex, prompted by suckling or uterine stretching, which enhances milk ejection and uterine contractions.
- Antidiuretic hormone (ADH), also termed vasopressin, is synthesized in the hypothalamus, primarily in the supraoptic nucleus, and stored in the posterior pituitary.
Feedback Mechanisms
- Negative feedback is essential in regulating thyroid hormone circulation; high hormone levels lead to decreased secretion of thyroid-stimulating hormone (TSH), which in turn lowers thyroid hormone production.
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Description
Test your knowledge on hormones and their signaling mechanisms with these flashcards. This quiz covers important concepts such as water-soluble hormones and the role of phosphodiesterase in cellular responses. Perfect for students studying anatomy and physiology.
