Endocrine

• Types of hormones

  • Peptide
  • Steroid
  • Amino-acid derived
• Peptide hormones

  • Water soluble and do not need a carrier through the blood
  • Indirect stimulators
  • Cannot pass through the plasma membrane
• Peptide hormones

  • Hormones from the hypothalamus and anterior pituitary
  • Glucagon and insulin
  • Calcitonin and PTH
• Steroid hormones

  • Lipid soluble and direct stimulators
  • Can pass through the plasma membrane
• Steroid hormones

  • Hormones from the adrenal cortex and reproductive organs
• Amino-acid derived hormones

  • Hormones from the adrenal medulla, thyroid, and melatonin
• Secondary messengers

  • cAMP
  • IP3
  • DAG
  • Ca
• Posterior pituitary gland

  • Does not produce its own hormones, and holds hormones from the hypothalamus
  • Stores oxytocin and ADH
• Anterior pituitary gland

  Releases LH, FSH, ACTH, TSH, prolactin, and GH
• Thyroid gland

  • Releases T3 and T4
  • T3 is the active form but T4 is the main circulating form because it is more stable
  • Parafollicular cells release calcitonin
• Adrenal medulla


  • Acted on by the sympathetic NS in response to short term stress
  • Releases the catecholamines epinephrine and norepinephrine
• Adrenal cortex

  • Releases glucocorticoids (ex. cortisol), mineralocorticoids (ex. aldosterone), and androgenic steroids in response to long term stress
  • Aldosterone increases Na reabsorption and K secretion, which increase blood pressure and volume