Topic One

• endocrinology is the study of hormones
• chemicals that coordinate different functions within the body by carrying messages through the blood

  Hormones
• Adrenal gland


  Release epinephrine and norepinephrine which helps the body deal with stress
• Parathyroid gland


  Four glands that release parathyroid hormone which regulates calcium levels in the blood
• Thymus


  During childhood releases GH which stimulates T Cell development
• Hypothalamus


  Makes hormones that control the pituitary gland, and are stored within the pituitary gland
• Pituitary gland


  Makes hormones that regulate many other endocrine glands
• Pineal gland


  Releases melatonin, involved in daily sleep-wake cycles
• Thyroid


  Produces thyroxine which regulates metabolism
• Pancreas


  Pancreas produces insulin and glucagon, which regulate blood sugar levels
• Ovary


  Produces estrogen and progesterone
• Testes


  Produces testosterone which is responsible for sperm
• Cell membrane receptors


  Most peptide hormones, act via second messengers or transcription factors
• Nuclear receptors


  Steroids and thyroid hormones act via transcription
• Agonists are hormone analogs that bind to receptors to mimic hormones
• Antagonists bind to receptors to prevent activation
• Non-neural endocrine cell do not create AP

  • transport into the blood stream
• Neurosecretory Cells create AP but do not act directly on another neuron
• All steroid hormones are synthesized from cholesterol
• Steps fo steroid synthesis;

  1. cholesterol imported into mitochondrial membrane by StAR
  2. converted to pregnenolone by enzyme Cyp11A1
  3. rest of synthesis occurs in the ER
• Peptide hormones are composed of amino acids

  • rapid diffusion
• Amine hormones

  • derviced from amino acids

  1. derived from tyrosine and tryptophan