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Chapters 6 and 8 (Physiology)

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Terms in this set (29)

  • Two types of cell-cell communication
    Electrical and Chemical communication.
  • Local cell communication methods
    Contact-dependent signals, Paracrine signals, and Autocrine signals.
  • Difference between paracrine and autocrine signals
    Paracrine signals act on neighboring cells; Autocrine signals act on the same cell that secreted them.
  • Why do only target cells respond to hormones in the blood?
    Only cells with specific receptors for that hormone respond.
  • Four major types of membrane receptors
    Receptor-channels, G protein-coupled receptors, Receptor enzymes, and Integrin receptors.
  • Where are receptors for lipophilic molecules located?
    In the cytoplasm or nucleus inside the cell.
  • Where are receptors for lipophobic molecules located?
    On the cell membrane surface.
  • Function of receptor-channels
    Open ion channels upon ligand binding, allowing ions like Na+, K+, or Cl- to flow, causing rapid cell depolarization.
  • G protein-coupled receptor pathways
    Activate G-proteins that either stimulate adenylate cyclase producing protein kinase A or phospholipase C producing DAG and protein kinase C.
  • Example of receptor enzyme pathway hormone
    Insulin binds receptor enzymes that trigger internal enzymatic activity.
  • Factors affecting target cell response magnitude
    Receptor affinity, ligand concentration, and number of receptors.
  • Difference between agonists and antagonists
    Agonists activate receptors to trigger responses; antagonists block receptors to prevent responses.
  • What is receptor down-regulation?
    Removal of receptors via endocytosis, leading to decreased cell sensitivity and possible drug tolerance.
  • What is receptor up-regulation?
    Increase in receptor number or cellular components, making cells more sensitive to signals.
  • How can one signal molecule have different effects in different tissues?
    Different receptor types (e.g., alpha vs beta adrenergic receptors) cause varied responses.
  • Properties of homeostatic control systems
    Include nervous and endocrine regulation, tonic control, antagonistic control, and one signal with different tissue effects.
  • Definition of hormones
    Chemical messengers secreted into blood by endocrine cells or glands to regulate distant target cells.
  • Three chemical classes of hormones
    Peptide, Steroid, and Amine hormones.
  • Characteristics of peptide hormones
    Hydrophilic, made on ribosomes, stored in vesicles, short half-life, bind membrane receptors.
  • Characteristics of steroid hormones
    Derived from cholesterol, hydrophobic, synthesized on demand, transported bound to carrier proteins, longer half-life, intracellular receptors.
  • Characteristics of amine hormones
    Derived from tyrosine or tryptophan; catecholamines are water soluble and bind membrane receptors; thyroid hormones are lipid soluble and bind intracellular receptors.
  • Primary vs secondary endocrine organs
    Primary organs secrete hormones as main function; secondary organs secrete hormones as a secondary function.
  • Simple reflex pathway in hormone control
    Endocrine cell senses stimulus and secretes hormone directly (e.g., PTH regulating plasma Ca2+).
  • Difference between anterior and posterior pituitary
    Anterior pituitary is a true endocrine gland; posterior pituitary stores and releases neurohormones made in hypothalamus.
  • What are tropic hormones?
    Hormones that regulate secretion of other hormones, often ending with '-tropin'.
  • Examples of posterior pituitary neurohormones
    Antidiuretic hormone (ADH) regulates water balance; Oxytocin stimulates milk ejection and uterine contractions.
  • Types of hormone interactions
    Synergism, permissiveness, and antagonism.
  • Cause of endocrine hypersecretion
    Often caused by benign or cancerous tumors or medical treatment.
  • Cause of endocrine hyposecretion
    Caused by gland atrophy, autoimmune disease, or damage anywhere in the hormone control pathway.