Endocrinology

• What are the two major control systems of the vertebrate body?

  The endocrine system and the nervous system
• Why is the endocrine system necessary for multicellular organisms?

  It is required for effective cell-cell communication and maintaining homeostasis
• What is the definition of a hormone?

  A chemical messenger produced and secreted by a specialized endocrine gland
• How are hormones transported in the body?

  Hormones are transported in the bloodstream to distant target organs or cells
• What influences circulating hormone levels?

  The rate of secretion by the endocrine gland and the rate of metabolism by target tissues
• What are the three classes of hormones?

  Proteins/peptides, cholesterol derivatives, and modified amino acids
• What is the role of specific receptors in hormone action?

  Specific receptors bind hormones and initiate a chain of events that results in a biological response
• How do water-soluble hormones differ from lipid-soluble hormones in terms of receptor location?

  Water-soluble hormones bind to receptors on the cell membrane, while lipid-soluble hormones bind to receptors inside the cell
• What are the physiological changes that regulate hormone secretion?

  • Blood glucose levels regulate insulin and glucagon release from the pancreas
  • Stress regulates adrenaline release from the adrenal medulla
  • Blood calcium levels regulate parathyroid hormone release from the parathyroids
• What are the feedback mechanisms that regulate hormone secretion?

  • Mostly negative feedback (closed-loop feedback) maintains homeostasis
  • Some positive feedback examples include:
  • Milk-ejection reflex involving oxytocin
  • Pre-ovulatory LH surge involving oestrogen
• What are the main types of endocrine dysfunction?

  Hyposecretion, hypersecretion, ectopic hormone secretion, and end organ insensitivity/resistance
• What causes hyposecretion of hormones?

  Causes include genetic factors, dietary deficiencies, immunological issues, cancer, iatrogenic factors, and idiopathic reasons
• What is a common treatment for hyposecretion of hormones?

  Hormone replacement therapy
• What are some causes of hypersecretion of hormones?

  Functional tumors, ectopic hormone-secreting tumors, and immunological factors
• What is a common treatment for hypersecretion of hormones?

  Surgical removal of the hyper-secreting gland
• What is the role of the hypothalamic-pituitary system?

  • Coordinates the entire endocrine system
  • Acts as the principal interface between the brain and the periphery
  • The pituitary gland is referred to as the "conductor of the endocrine orchestra"
• Where is the pituitary gland located?

  In a bony cavity at the base of the brain called the Sella Turcica
• What hormones are produced by the anterior pituitary gland?

  • Gonadotrophins (regulate reproductive function)
  • Thyrotrophin (regulates thyroid)
  • Growth hormone
  • Prolactin (regulates milk production)
  • Adrenocorticotrophin (regulates adrenals)
• What hormones are produced by the posterior pituitary gland?

  • Oxytocin (prostate and uterine function)
  • Vasopressin (ADH) (kidney function)
• What is pan-hypopituitarism?

  It is the undersecretion of multiple pituitary hormones leading to reduced end-organ function
• What is the treatment for hypopituitarism?

  Tumor removal and multiple hormone replacement therapy
• What are the effects of thyroid hormones?

  • Calorigenic (heat-producing)
  • Increases basal metabolic rate (BMR)
  • Increases heart rate and force of contraction
  • Essential for growth and maturation
• What is hypothyroidism?

  A lack of thyroid hormone
• What are the common symptoms of hypothyroidism in adults?

  Weight gain, cold intolerance, lethargy, depression, and sluggish reflexes
• What is cretinism?


  A condition resulting from hypothyroidism in a fetus or child, leading to severe developmental issues
• What is the treatment for hypothyroidism?

  Lifelong replacement therapy with T4
• What is hyperthyroidism?

  An excess of thyroid hormone
• What are the common symptoms of hyperthyroidism?

  Weight loss, nervousness, heat intolerance, and high cardiac output
• What is the most common cause of hyperthyroidism?

  Graves disease
• What is the treatment for hyperthyroidism?

  Anti-thyroid drugs, surgical removal, or radioactive iodine ablation
• What hormones are secreted by the adrenal medulla and cortex?

  • Adrenal medulla: Adrenaline (epinephrine)
  • Adrenal cortex: Cortisol and aldosterone
• What is Addison's disease?

  A deficiency of adrenocortical hormones
• What are the symptoms of Addison's disease?

  Weight loss, muscle weakness, fatigue, and low blood pressure
• What is Cushing's syndrome?

  An excess of cortisol
• What are the symptoms of Cushing's syndrome?

  Raised blood glucose levels, muscle mass loss, and fat deposition around the abdomen
• What is pheochromocytoma?

  A tumor of the adrenal medulla that causes episodic hypertension
• What is the treatment for pheochromocytoma?

  Alpha- and beta-adrenoceptor blockers and tumor removal