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Endocrine System - Anatomy & Physiology

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  • Difference between nervous and endocrine systems
    Nervous system uses electrical impulses for fast, short-term responses; endocrine system uses hormones for slower, long-lasting effects.
  • Autocrine, paracrine, and endocrine factors
    Autocrine: act on the same cell; paracrine: act on nearby cells; endocrine: hormones travel through blood to distant targets.
  • Chemical classes of hormones
    Hormones are classified as amino acid derivatives, peptides/proteins, and steroids.
  • Primary endocrine organs
    Include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pineal gland, pancreas, ovaries, and testes.
  • Mechanisms of hormone action
    Hormones act via cAMP, Ca2+ second messengers, steroid hormone receptors, thyroxine mechanisms, and tyrosine kinase receptors.
  • Factor affecting cell response to hormone
    The number and sensitivity of hormone receptors on the target cell determine its response.
  • Downregulation vs. upregulation of hormone receptors
    Downregulation: decrease in receptor number due to high hormone levels; upregulation: increase in receptors due to low hormone levels.
  • Antagonistic, permissive, and synergistic hormone effects
    Antagonistic: hormones oppose each other; permissive: one hormone enhances another's effect; synergistic: hormones work together for greater effect.
  • Negative feedback in hormone regulation
    Hormone levels are regulated by negative feedback loops that reduce hormone secretion when levels are sufficient.
  • Three endocrine gland stimuli
    Stimuli include humoral (blood levels), neural (nerve signals), and hormonal (hormones stimulating other glands).
  • Command center of the endocrine system
    The hypothalamus controls the endocrine system by regulating the pituitary gland.
  • Hormones secreted by hypothalamus and pituitary
    Hypothalamus secretes releasing/inhibiting hormones; anterior pituitary releases hormones like GH, TSH, ACTH; posterior pituitary releases ADH and oxytocin.
  • Hypophyseal portal system
    A network of blood vessels connecting the hypothalamus to the anterior pituitary for hormone transport.
  • Thyroid hormone synthesis and types
    Thyroid hormones are made in the thyroid gland; T4 (thyroxine) and T3 differ in iodine content and activity.
  • Functions of thyroxine (TH)
    TH regulates metabolism, growth, and development.
  • How calcitonin lowers blood calcium
    Calcitonin decreases blood calcium by inhibiting osteoclast activity and promoting calcium deposition in bones.
  • Location of parathyroid glands
    Parathyroid glands are located on the posterior surface of the thyroid gland.
  • Regulation of blood calcium by PTH and calcitonin
    PTH increases blood calcium by stimulating bone resorption; calcitonin lowers it by inhibiting bone resorption.
  • Three phases of General Adaptation Syndrome
    Phases are alarm, resistance, and exhaustion in response to stress.
  • Adrenal cortex layers and hormones
    Layers: zona glomerulosa (mineralocorticoids), zona fasciculata (glucocorticoids), zona reticularis (androgens).
  • Adrenal medulla secretion and function
    Secretes epinephrine and norepinephrine for fight-or-flight response.
  • Function of pineal gland and melatonin
    Pineal gland secretes melatonin, which regulates circadian rhythms and sleep.
  • Hormones from ovaries, testes, and placenta
    Ovaries produce estrogen and progesterone; testes produce testosterone; placenta produces hormones supporting pregnancy.
  • Pancreatic hormone secretion
    Alpha cells secrete glucagon, beta cells secrete insulin, delta cells secrete somatostatin, PP cells secrete pancreatic polypeptide.
  • Glucagon and insulin in blood glucose homeostasis
    Glucagon raises blood glucose; insulin lowers blood glucose.
  • Definition and types of diabetes
    Diabetes is a disorder of blood glucose regulation; Type I is insulin deficiency; Type II is insulin resistance.
  • Organs with secondary endocrine functions
    Include heart, kidneys, digestive tract, and adipose tissue, secreting hormones like ANP, erythropoietin, and others.
  • Embryonic germ layers of endocrine glands
    Endocrine glands arise from ectoderm, mesoderm, or endoderm depending on the gland.
  • Common endocrine disorders and causes
    Disorders include dwarfism, gigantism, acromegaly, goiter, cretinism, Grave's disease, Cushing's syndrome, and Addison's disease.