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Endocrine System - Anatomy & Physiology

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이 집합의 용어 (28)

  • What are the general functions of the endocrine system?
    The endocrine system regulates body functions through hormones, controlling metabolism, growth, reproduction, and homeostasis.
  • What is a hormone?
    A hormone is a chemical messenger secreted by endocrine glands that travels through the bloodstream to target cells to regulate physiological processes.
  • What defines a target cell in the endocrine system?
    A target cell has specific receptors for a hormone; when the hormone binds, it triggers a cellular response.
  • How do hormones control the correct cells?
    Hormones control correct cells by binding only to cells with specific receptors for that hormone.
  • What is receptor distribution and its significance?
    Receptor distribution means not all cells have the same hormone receptors, allowing hormones to affect only specific cells.
  • What is up-regulation of hormone receptors?
    Up-regulation is the increase in receptor number on a cell, making it more sensitive to a hormone.
  • What is down-regulation of hormone receptors?
    Down-regulation is the decrease in receptor number on a cell, reducing its sensitivity to a hormone.
  • Compare the nervous and endocrine systems in chemical messengers and target delivery.
    Nervous system uses neurotransmitters released at synapses; endocrine system uses hormones released into blood to reach distant targets.
  • Compare the time required for nervous vs. endocrine system effects.
    Nervous system effects are rapid and short-lived; endocrine system effects are slower to start but longer lasting.
  • What are the two main chemical classes of hormones?
    Amino acid-based hormones (hydrophilic except thyroid hormone) and steroid hormones (hydrophobic, derived from cholesterol).
  • Where are receptors for hydrophilic vs. hydrophobic hormones located?
    Hydrophilic hormone receptors are on the cell membrane; hydrophobic hormone receptors are inside the cell, often in the nucleus.
  • Why can't most amino acid-based hormones enter target cells?
    Because they are hydrophilic and cannot cross the lipid plasma membrane, they bind to surface receptors.
  • What is signal transduction in hormone action?
    Signal transduction is the process by which a hormone binding to a receptor triggers a cascade of intracellular events leading to a response.
  • Describe kinase receptors and their role.
    Kinase receptors are membrane proteins that phosphorylate enzymes when a hormone binds, activating intracellular signaling pathways.
  • What is the second messenger mechanism in hormone action?
    Hormone binding activates a membrane receptor that produces a second messenger (e.g., cAMP) inside the cell to amplify the signal.
  • In the cAMP second messenger system, what enzyme produces cAMP?
    Adenylyl cyclase is the membrane-bound enzyme that converts ATP to cAMP.
  • What is the function of protein kinases in hormone signaling?
    Protein kinases phosphorylate proteins to alter their activity, mediating the cellular response to hormones.
  • How are hydrophobic hormones able to affect target cells?
    They diffuse through the plasma membrane, bind intracellular receptors, and directly activate gene transcription.
  • Where does signal amplification occur in hormone action?
    Amplification occurs at the target cell, where one hormone molecule can trigger the production of many second messengers.
  • What is negative feedback in hormone secretion control?
    Negative feedback reduces hormone secretion when blood hormone levels are high to maintain homeostasis.
  • Give an example of neural control of hormone secretion.
    Neural control involves nerve signals stimulating hormone release, such as the milk let-down reflex triggered by oxytocin.
  • What is the body's main biological clock and its role in hormone rhythms?
    The suprachiasmatic nucleus in the hypothalamus controls circadian rhythms, regulating 24-hour hormone release cycles.
  • Define permissiveness in hormone interactions.
    Permissiveness occurs when one hormone enhances the effect of another hormone.
  • Define antagonism in hormone interactions.
    Antagonism occurs when one hormone opposes or inhibits the action of another hormone.
  • How are hydrophobic hormones transported in the blood?
    They bind to transport proteins, which carry them through the bloodstream.
  • What is hyposecretion and hypersecretion of hormones?
    Hyposecretion is insufficient hormone secretion; hypersecretion is excessive hormone secretion.
  • What is the difference between primary and secondary hormone disorders?
    Primary disorders originate in the endocrine gland; secondary disorders result from problems outside the gland, such as pituitary dysfunction.
  • How does receptor number affect hormone function?
    Changes in receptor number alter cell sensitivity, affecting the magnitude of the hormone's effect.