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Anatomy & Physiology: The Endocrine System

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이 집합의 용어 (34)

  • What is the primary function of the endocrine system?
    To coordinate and integrate body cell activities by releasing hormones into the blood, influencing metabolic activities with slower but longer-lasting responses than the nervous system.
  • Name the main endocrine glands.
    Pituitary, thyroid, parathyroid, adrenal, and pineal glands.
  • What are the two main classes of hormones?
    Amino acid–based hormones (including peptides and proteins) and steroids synthesized from cholesterol.
  • How do hormones affect target cells?
    By altering plasma membrane permeability, stimulating enzyme or protein synthesis, activating/deactivating enzymes, inducing secretory activity, or stimulating mitosis.
  • What triggers hormone release in the endocrine system?
    Endocrine gland stimuli (humoral, neural, hormonal) and nervous system modulation.
  • Define humoral stimuli in hormone release.
    Changing blood levels of ions and nutrients directly stimulate hormone secretion, e.g., low blood Ca2+ triggers parathyroid hormone release.
  • What is neural stimuli in hormone release?
    Nerve fibers stimulate hormone release, such as sympathetic fibers triggering adrenal medulla to secrete catecholamines.
  • Explain hormonal stimuli in hormone release.
    Hormones stimulate other endocrine glands to release hormones, e.g., hypothalamic hormones stimulate anterior pituitary hormones.
  • What determines target cell specificity for hormones?
    Presence of specific receptors, blood hormone levels, receptor number, and receptor-hormone binding affinity.
  • What is up-regulation and down-regulation of hormone receptors?
    Up-regulation: target cells increase receptors in response to low hormone levels. Down-regulation: target cells decrease receptors due to high hormone levels.
  • What is the half-life of a hormone?
    The time required for the blood level of a hormone to decrease by half, varying from minutes to days depending on the hormone.
  • Describe permissiveness in hormone interaction.
    One hormone cannot exert its full effect without another hormone being present.
  • What is synergism in hormone action?
    Multiple hormones produce the same effect on a target cell, amplifying the response.
  • Define antagonism in hormone interaction.
    One hormone opposes the action of another, e.g., insulin and glucagon.
  • What hormones are secreted by the posterior pituitary?
    Oxytocin and antidiuretic hormone (ADH), both produced by hypothalamic neurons and stored in the posterior pituitary.
  • What are the main functions of oxytocin?
    Stimulates uterine contractions during childbirth and triggers milk ejection during breastfeeding.
  • How does antidiuretic hormone (ADH) regulate water balance?
    ADH targets kidney tubules to reabsorb water, reducing urine output; high concentrations cause vasoconstriction.
  • List the six anterior pituitary hormones.
    Growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL).
  • What are the direct metabolic effects of growth hormone (GH)?
    Decreases glucose uptake, triggers glycogen breakdown, increases fatty acid levels, and promotes protein synthesis.
  • How is growth hormone (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?
    Released in response to corticotropin-releasing hormone (CRH) from the hypothalamus, with feedback inhibition by cortisol.
  • What are the functions of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)?
    FSH stimulates gamete production; LH promotes gonadal hormone production and triggers ovulation in females.
  • What hormone does prolactin (PRL) regulate and how is it controlled?
    Stimulates milk production; regulated mainly by prolactin-inhibiting hormone (dopamine) and stimulated by estrogen and suckling.
  • What are the two main thyroid hormones and their effects?
    T4 (thyroxine) and T3 (triiodothyronine); they increase basal metabolic rate, regulate growth, development, and maintain blood pressure.
  • What is the role of parathyroid hormone (PTH)?
    Maintains calcium homeostasis by stimulating bone resorption, increasing kidney reabsorption of Ca2+, and activating vitamin D for intestinal absorption.
  • What hormones are produced by the adrenal cortex?
    Mineralocorticoids (e.g., aldosterone), glucocorticoids (e.g., cortisol), and gonadocorticoids (weak androgens).
  • Describe the renin-angiotensin-aldosterone mechanism.
    Low blood pressure triggers renin release, leading to angiotensin II formation, which stimulates aldosterone release to increase blood volume and pressure.
  • What are the main effects of cortisol?
    Increases blood glucose via gluconeogenesis, promotes fat and protein metabolism, enhances vasoconstriction, and suppresses inflammation and immune response.
  • What hormones are secreted by the adrenal medulla?
    Catecholamines: epinephrine (80%) and norepinephrine (20%), which increase heart rate, blood glucose, and cause vasoconstriction.
  • What hormone does the pineal gland secrete and its function?
    Melatonin, which regulates circadian rhythms, sexual maturation timing, and physiological processes with rhythmic variations.
  • What are the endocrine functions of the pancreas?
    Alpha cells produce glucagon to raise blood glucose; beta cells produce insulin to lower blood glucose.
  • How does insulin lower blood glucose levels?
    Enhances glucose uptake by cells, inhibits glycogen breakdown, and prevents conversion of amino acids/fats to glucose.
  • What are the primary sex hormones produced by the gonads?
    Ovaries produce estrogens and progesterone; testes produce testosterone.