Endocrine system

• What are the major endocrine glands?

  • Thyroid
  • Parathyroid
  • Ovary
  • Testis
  • Adrenal
  • Pancreas
  • Pituitary
• What controls the pituitary gland?

  Hypothalamus
• Which glands are under pituitary control?

  • Thyroid
  • Ovary
  • Testis
  • Adrenal
• Where can you find individual endocrine cells?

  Scattered through GI tract & skin
• What does the thyroid gland secrete?

  Thyroxine (T4 & T3)

  Calcitonin

  Has glandular epithelium & product enters bloodstream

  Highly vascularised
• What are the 2 types of hormone?

  • Steroid (potent) (oestrogens, aldosterone)
  • Non-steroid (diverse: eicosanoids, peptides, amines, insulin, growth hormone)
• What are the causes of endocrine diseases?

  • Hormone resistance (receptor defects)
  • Hormone excess (tumours of gland & overstimulation)
  • Hormone deficiency (gland destruction)
• What happens in Type 1 diabetes?

  Insulin deficiency
• What hormones are important during puberty?

  • Adrenal glands activated to make adrenal androgen
  • Growth hormone
  • Oestrogen
  • Testosterone
• What may a pituitary tumour cause?

  Acromegaly (excess growth hormone in adulthood)
• Properties of peptide/protein hormones?

  • Hydrophilic
  • Exocytosis secretion
  • Amino acid chain structure
  • Cell surface receptor
  • Transported in blood as free hormone
  • E.g, Oxytocin & ADH
  • Made through gene transcription & post-translational modification in golgi
  • Stored in secretory granules
  • Injected so don't enter gut to be degraded by acid environment & enzymes
• Properties of steroid hormones?

  • Lipophilic
  • Can't be stored in vesicles so made on demand instead
  • Cholesterol derived
  • Intracellular receptors
  • Simple diffusion
  • Bound to transport proteins in blood
  • E.g, cortisol & glucocorticoid
  • Given by patch
  • Potent so only need a low conc.
  • Act slower than neurotransmitters
• What is the mechanism of steroid hormones?

  Activation of specific genes to produce new proteins
• What is the mechanism of peptide hormones?

  Activation of second messenger system to alter activity of existing proteins
• How many hormones does the pituitary gland secrete?

  8
• Which hormones does the anterior pituitary secrete?

  • FSH
  • TSH
  • LH
  • ACTH
  • Prolactin
  • Growth hormone

  (hormones with tropic action)
• Which hormones does the posterior pituitary secrete?

  • Oxytocin
  • ADH
• Which pituitary lobe is larger?

  Anterior
• What is the anterior pituitary lobe controlled by?

  Hormones made in hypothalamus

  Neuron axons short & stop at hypothalamus base

  Release hormone into blood into pituitary (Forward drive)

  Indirect control
• What does the pituitary blood portal system control?

  Glandular tissue
• How does the posterior pituitary work?

  Neurosecretory cells in hypothalamus with longer axons that pass down pituitary stalk & their terminals form posterior pituitary

  Direct control