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Endocrine System - Anatomy & Physiology

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이 집합의 용어 (29)

  • What are the two major control systems of the body?
    The endocrine system and the nervous system coordinate and integrate body cell activities.
  • How do endocrine and nervous systems differ in response speed and duration?
    The nervous system initiates rapid, short-duration responses via action potentials, while the endocrine system initiates slower, long-duration responses via hormones.
  • What are hormones and how do they travel to target cells?
    Hormones are chemical messengers secreted by endocrine glands that travel through the blood to reach target cells.
  • What distinguishes endocrine glands from exocrine glands?
    Endocrine glands are ductless and secrete hormones directly into extracellular fluid; exocrine glands have ducts and secrete nonhormonal substances.
  • Name three types of chemical messengers and their range of action.
    Hormones act over long distances via blood; autocrines affect the same cell that secretes them; paracrines affect neighboring cells locally.
  • What determines a hormone's mode of action?
    A hormone's chemical structure determines its solubility, transport in blood, receptor type, and degradation rate.
  • What are the two main classes of hormones based on chemical structure?
    Amino acid–based hormones (water soluble) and steroid hormones (lipid soluble).
  • How do water-soluble hormones act on target cells?
    They bind to plasma membrane receptors and use second messenger systems like cyclic AMP to alter cell activity.
  • How do lipid-soluble hormones act on target cells?
    They diffuse through the plasma membrane, bind intracellular receptors, and directly activate gene transcription.
  • Describe the cyclic AMP (cAMP) second messenger mechanism.
    Hormone binds receptor → activates G protein → activates adenylate cyclase → converts ATP to cAMP → cAMP activates protein kinases → cellular response.
  • What is the role of phospholipase C in hormone signaling?
    Activated by G protein, it splits PIP2 into DAG and IP3; DAG activates protein kinases, IP3 releases Ca2+ as a second messenger.
  • What are the three types of stimuli that trigger hormone release?
    Humoral stimuli (blood ion/nutrient levels), neural stimuli (nerve fibers), and hormonal stimuli (hormones stimulating other glands).
  • How does the nervous system modulate hormone release?
    It can override endocrine controls by modifying stimulation or inhibition of glands, especially during stress.
  • What factors influence target cell activation by hormones?
    Blood hormone levels, number of receptors on target cells, and receptor-hormone binding affinity.
  • What is up-regulation and down-regulation of hormone receptors?
    Up-regulation is increasing receptor numbers in response to low hormone levels; down-regulation is decreasing receptors due to high hormone levels.
  • What is the half-life of a hormone?
    The time required for the blood concentration of a hormone to decrease by half.
  • Compare lipid-soluble and water-soluble hormones in terms of transport and receptor location.
    Lipid-soluble hormones bind plasma proteins and have intracellular receptors; water-soluble hormones circulate freely and bind plasma membrane receptors.
  • Define permissiveness, synergism, and antagonism in hormone interactions.
    Permissiveness: one hormone needs another to act; synergism: combined hormones amplify effects; antagonism: one hormone opposes another.
  • How does the hypothalamus control the pituitary gland?
    It releases hormones that regulate anterior pituitary secretion and produces neurohormones stored in the posterior pituitary.
  • What hormones are stored and released by the posterior pituitary?
    Oxytocin and antidiuretic hormone (ADH), both produced by hypothalamic neurons.
  • What are the main functions of oxytocin?
    Stimulates uterine contractions during childbirth and triggers milk ejection during breastfeeding.
  • What triggers ADH release and what are its effects?
    High blood osmolarity triggers ADH release; it promotes water reabsorption in kidneys and causes vasoconstriction.
  • What are the six hormones secreted by the anterior pituitary?
    Growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).
  • What are the direct and indirect actions of growth hormone (GH)?
    Direct: alters metabolism to increase blood glucose and fat breakdown; Indirect: stimulates IGFs that promote cell growth and division.
  • How is GH secretion regulated?
    Stimulated by growth hormone-releasing hormone (GHRH) and inhibited by growth hormone-inhibiting hormone (GHIH or somatostatin).
  • What is the role of thyroid-stimulating hormone (TSH)?
    Stimulates thyroid gland development and secretion of thyroid hormones.
  • How is adrenocorticotropic hormone (ACTH) regulated and what does it do?
    Stimulated by corticotropin-releasing hormone (CRH); stimulates adrenal cortex to release glucocorticoids.
  • What are gonadotropins and their functions?
    Follicle-stimulating hormone (FSH) stimulates gamete production; luteinizing hormone (LH) promotes gonadal hormone production and ovulation.
  • What is the function of prolactin (PRL)?
    Stimulates milk production in females; regulated mainly by prolactin-inhibiting hormone (dopamine).