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Endocrine System - Anatomy & Physiology

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Terms in this set (25)

  • Difference between endocrine and exocrine glands
    Endocrine glands are ductless and release hormones into the blood; exocrine glands use ducts to secrete substances.
  • Major hormone classes
    Two main classes: amino acid–based hormones and steroids. Steroids are synthesized from cholesterol.
  • Hormone receptor location for water-soluble vs lipid-soluble hormones
    Water-soluble hormones bind to plasma membrane receptors; lipid-soluble hormones bind to intracellular receptors.
  • Main mechanism of water-soluble hormone action
    Use G protein and second messenger systems like cAMP or PIP₂-Ca²⁺ to trigger cellular responses.
  • Main mechanism of lipid-soluble hormone action
    Directly activate genes by binding intracellular receptors, leading to gene transcription and protein synthesis.
  • cAMP second messenger pathway sequence
    Hormone → receptor → G protein → adenylate cyclase → cAMP → protein kinase → cellular response.
  • Types of hormone stimuli
    Humoral: blood ion/nutrient changes; Neural: nerve fibers stimulate secretion; Hormonal: one hormone triggers another.
  • Up-regulation vs down-regulation of hormone receptors
    Up-regulation: more receptors when hormone levels are low; down-regulation: fewer receptors when hormone levels are high.
  • Permissiveness, synergism, and antagonism in hormones
    Permissiveness: one hormone needs another to act fully; Synergism: hormones reinforce each other; Antagonism: hormones oppose each other.
  • Difference between anterior and posterior pituitary
    Posterior pituitary is neural tissue storing hypothalamic hormones; anterior pituitary is glandular tissue regulated by hypothalamic releasing/inhibiting hormones.
  • ADH source, target, and effect
    Produced by hypothalamus, released from posterior pituitary; targets kidneys to increase water reabsorption.
  • Oxytocin function and feedback type
    Stimulates uterine contractions and milk ejection; operates via positive feedback.
  • Growth hormone (GH) effects and disorders
    Promotes growth and metabolism; excess causes gigantism in children, acromegaly in adults; deficiency causes pituitary dwarfism.
  • Three major pituitary hormone axes
    Thyroid axis: TRH → TSH → T3/T4; Adrenal axis: CRH → ACTH → cortisol; Gonadal axis: GnRH → FSH/LH → gonadal hormones.
  • Thyroid hormone synthesis sequence
    1. Thyroglobulin made; 2. Iodide trapped; 3. Iodide oxidized; 4. Iodine attaches to tyrosines; 5. MIT + DIT form T3, DIT + DIT form T4; 6. Colloid endocytosed; 7. T3/T4 secreted.
  • Difference between T3 and T4
    T4 has four iodine atoms; T3 has three and is more active. Peripheral tissues convert T4 to T3.
  • Effects of thyroid hormone (TH)
    Increases basal metabolic rate, heat production, and supports normal growth and development.
  • Parathyroid hormone (PTH) role in calcium regulation
    PTH increases blood Ca²⁺ by stimulating bone resorption, renal Ca²⁺ reabsorption, vitamin D activation, and intestinal Ca²⁺ absorption.
  • Adrenal cortex zones and their hormones
    Zona glomerulosa: aldosterone (salt); Zona fasciculata: cortisol (sugar); Zona reticularis: gonadocorticoids (sex).
  • RAAS pathway in response to low blood pressure
    Low BP → kidney renin ↑ → angiotensin II ↑ → aldosterone ↑ → renal Na⁺ reabsorption ↑ → blood volume and BP ↑.
  • Insulin vs glucagon effects on blood glucose
    Insulin lowers blood glucose by promoting uptake and storage; glucagon raises blood glucose by stimulating glycogenolysis and gluconeogenesis.
  • Type 1 vs Type 2 diabetes mellitus
    Type 1: insulin hyposecretion; Type 2: insulin resistance or hypoactivity.
  • Symptoms of diabetes mellitus
    Polyuria (excessive urine), polydipsia (excessive thirst), and polyphagia (excessive hunger).
  • Hormones secreted by non-classic endocrine organs
    Examples: adipose (leptin), GI tract (gastrin), heart (ANP), kidneys (erythropoietin), skin (cholecalciferol).
  • Effect of aging on growth hormone and thyroid hormone
    GH and TH decline with age, contributing to muscle atrophy and lower basal metabolic rate.