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Anatomy & Physiology: Endocrine System and Blood

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Terms in this set (28)

  • Endocrine system function
    Coordinates body cell activity via hormones transported in blood; controls reproduction, growth, metabolism, and defense mobilization.
  • Difference between endocrine and exocrine glands
    Endocrine glands produce hormones and lack ducts; exocrine glands produce nonhormonal substances and have ducts.
  • Two main classes of hormones
    Amino acid–based hormones (peptides, proteins) and steroids (synthesized from cholesterol).
  • Target cells in hormone action
    Cells with specific receptors for a hormone; hormones alter their activity by changing membrane permeability, enzyme activity, secretion, or mitosis.
  • Three stimuli triggering hormone release
    Humoral (blood ion/nutrient levels), neural (nerve fibers), and hormonal (hormones stimulating other glands).
  • Up-regulation vs. down-regulation of hormone receptors
    Up-regulation: increase receptors due to low hormone levels; down-regulation: decrease receptors due to high hormone levels.
  • Half-life of hormones
    Time for blood hormone level to decrease by half; varies from minutes to a week depending on hormone.
  • Permissiveness, synergism, and antagonism in hormone interaction
    Permissiveness: one hormone needs another to act; synergism: hormones amplify effects; antagonism: hormones oppose each other.
  • Posterior pituitary hormones and origin
    Oxytocin and ADH produced by hypothalamic neurons; stored and released by posterior pituitary.
  • Growth hormone (GH) effects
    Direct metabolic effects (glucose sparing, fat breakdown) and indirect growth promotion via IGFs stimulating cell growth and protein synthesis.
  • Thyroid hormone forms and effects
    T4 (thyroxine) and T3 (triiodothyronine); increase basal metabolic rate, regulate growth, development, and maintain blood pressure.
  • Parathyroid hormone (PTH) role
    Increases blood Ca2+ by stimulating bone resorption, kidney reabsorption, and activating vitamin D for intestinal absorption.
  • Aldosterone function
    Mineralocorticoid that stimulates Na+ reabsorption and K+ elimination by kidneys, increasing blood volume and pressure.
  • Renin-angiotensin-aldosterone mechanism
    Low blood pressure triggers renin release, leading to angiotensin II formation, which stimulates aldosterone release.
  • Cortisol effects
    Raises blood glucose via gluconeogenesis, promotes fat and protein metabolism, enhances vasoconstriction, and suppresses inflammation.
  • Adrenal medulla hormones and effects
    Epinephrine and norepinephrine increase heart rate, blood glucose, and cause vasoconstriction; epinephrine stimulates metabolism more.
  • Pancreatic islet hormones
    Alpha cells produce glucagon (raises blood glucose); beta cells produce insulin (lowers blood glucose).
  • Insulin actions
    Enhances glucose uptake by cells, inhibits glycogen breakdown, and promotes glucose storage as glycogen or fat.
  • Erythrocyte structure
    Biconcave, anucleate cells filled with hemoglobin for efficient oxygen transport.
  • Erythropoiesis regulation
    Stimulated by erythropoietin (EPO) from kidneys in response to hypoxia; requires iron, vitamin B12, and folic acid.
  • Hemoglobin composition
    Four polypeptide chains (two alpha, two beta) each with a heme group containing iron that binds oxygen.
  • Leukocyte categories
    Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).
  • Neutrophil function
    Most abundant WBC; phagocytizes bacteria and kills microbes via respiratory burst.
  • Platelet function
    Cell fragments that form temporary plugs to seal vessel breaks and release chemicals for clotting.
  • Three steps of hemostasis
    Vascular spasm, platelet plug formation, and coagulation (clotting).
  • Intrinsic vs. extrinsic coagulation pathways
    Intrinsic triggered by blood factors; extrinsic triggered by tissue factor outside blood; both activate factor X.
  • Coagulation final steps
    Prothrombin activator converts prothrombin to thrombin; thrombin converts fibrinogen to fibrin forming clot mesh.
  • Blood types ABO and Rh
    ABO groups based on A and B antigens; Rh factor based on presence of D antigen; mismatches cause transfusion reactions.