Lecture 29 - Endocrine Disorders

• Cortisol


  Stimulates pancreatic alpha cells to secrete glucagon
• What can go wrong with hormone signalling?
• Secretion levels


  • Hyposecretion - Too little hormone is secreted into the plasma
  • Hypersecretion - Too much hormone is secreted into the plasma
• Hyposensitive


  Receptors are less sensitive; receptors get desensitised, causing them to respond less or not at all
• Addison's Disease


  Hyposecretion of cortisol and aldosterone
• Addison's Disease


  • Common cause - Autoimmune disease that attacks the adrenal cortex
  • Hyposecretion disorder - Reduced cortisol and aldosterone secretion causes reduction in normal effects
  • Symptoms - Low blood pressure, Loss of appetite, weight loss
• Cushing's Disease


  Hypersecretion of Cortisol
• Cushing's Disease


  • Common cause: Adrenal cortex tumor or taking glucocorticoid medication for long periods (e.g. prednisone)
  • Hypersecretion disorder: Excess cortisol secretion causes amplification of normal effects, plus other symptoms with Cushing's
  • Symptoms: High blood pressure, Thinning of arms and legs; weight gain in torso
• Dwarfism


  Hyposecretion of growth hormone
• Dwarfism


  • Common causes - Genetic mutation or inheritance (e.g. have short parents)
  • Hyposecretion disorder - reduced growth hormone secretion
  • Symptoms: Short stature
• Gigantism


  Hypersecretion of growth hormone
• Gigantism


  • Common cause - pituitary gland tumor in childhood
  • Hypersecretion disorder - Excess growth hormone secretion before long bones have stopped growing (epiphyseal plates have yet not fused)
  • Symptoms - Tall stature
• Acromegaly


  Hypersecretion of growth hormone
• Acromegaly


  • Common cause - Pituitary gland tumor in early adulthood
  • Hypersecretion disorder - Excess growth hormone secretion after long bones have stopped growing (epiphyseal plates have fused)
  • Symptoms - Large and irregularly shaped extremities and characteristic facial features
• Infantile hypothyroidism


  Hyposecretion of thyroid hormone
• Infantile hypothyroidism


  • Common causes - Missing or poorly developed thyroid gland, Poorly functioning anterior pituitary, Lack of iodine in mother's diet
  • Hyposecretion disorder - reduced secretion of thyroid hormone causes reductions of its normal effects, plus other symptoms
  • Symptoms include: Low metabolic rate, Delayed growth and development
• Adult hypothyroidism


  Hyposecretion of thyroid hormone
• Adult hypothyroidism


  • Common causes - Autoimmune disease that attacks thyroid hormone, Iodine deficiency in diet, Surgical removal of thyroid gland
  • Hyposecretion disorder - Reduced secretion of thyroid hormone causes reductions of its normal effects
  • Some symptoms - Low metabolic rate; tiredness, Weight gain, Sensitive to cold - not as much thermogenesis, Depression; brain fog
• Simple Goitre


  Hyposecretion of thyroid hormone
• Simple Goitre


  • Common cause: lack of iodine in diet
  • Hyposecretion disorder: Without iodine, the thyroid gland cannot make thyroid hormone. Without thyroid hormone negatively feeding back, TRH and TSH get continually secreted. Excess TSH causes the thyroid gland to swell
  • Symptoms - Enlarged thyroid gland = a goitre
• Graves Disease


  Hypersecretion of thyroid hormone
• Graves Disease


  • Cause - Autoimmune disorder
  • Hypersecretion disorder - Excess secretion of thyroid hormone causes amplifications of its normal effects, plus other symptoms
  • Some symptoms: High metabolic rate; weight loss, Increased heart rate, Sensitive to heat, Nervousness, neurons working too hard, Exophthalmos (bulging eyes), Goitre (thyroid swelling)
• Hyperparathyroidism


  Hypersecretion of parathyroid hormone
• Hyperparathyroidism


  • Common cause - Parathyroid tumor
  • Hypersecretion disorder - Excess secretion of parathyroid hormone causes amplifications of its normal effects
  • Some symptoms - Bones become soft, deformed and fragile, Kidney stones (excess Ca2+ accumulates in the kidney)
• Hypoparathyroidism


  Hyposecretion of parathyroid hormone
• Hypoparathyroidism


  • Common cause - damaged parathyroid glands due to genetic or autoimmune disease
  • Hyposecretion disorder - reduced secretion of parathyroid hormone causes reduced plasma [calcium] – hypocalcemia
  • Some symptoms: Muscle tetany (tetanus); muscle spasms/cramps, effects ion concentration, increases resting membrane potential (easier to bring to threshold), Seizures, affecting nervous system (Neurons)
• Type I Diabetes Mellitus

  Hyposecretion of insulin
• Type I Diabetes Mellitus

  • Common cause - Beta islet cells in pancreas get destroyed by a virus or autoimmune disease
  • Hyposecretion disorder - Reduced secretion of insulin causes symptoms related to chronically high plasma glucose (which can damage blood vessels & nerves), with inability for cells to use the glucose
  • Some symptoms - Polyuria (excessive urine production), Polydipsia (excessive thirst), Diabetic neuropathy and retinopathy, Cardiovascular issues
  • Treatment: requires insulin injections or infusion
• Insulin Resistance and Type II Diabetes Mellitus

  • Hyposensitivity disorder (Insulin resistance) - insulin receptors on target cells become insensitive (resistant) to insulin due to chronically high insulin levels
  • Hyposensitivity and Hyposecretion disorder (Type II Diabetes) - As insulin resistance gets worse the pancreatic beta islet cells wear out. This leads to progressively reduced insulin secretion
• Insulin Resistance and Type II Diabetes Mellitus


  • Common cause - Unhealthy lifestyle - inactivity, poor diet, obesity
  • Some symptoms - Polyuria (excessive urine production), Polydipsia (excessive thirst), Diabetic neuropathy and retinopathy, Cardiovascular issues
  • Treatment and prevention - Insulin, exercise, good diet