The endocrine system

• The endocrine system is in the body.

  It uses blood to transport signals (hormones)

  This means that the signal can be released inside of the body and will be transported throughout the body.

  It is slower than the nervous system.
• Endocrine gland

  • Contains cells that produce a hormoe and release it straight into the blood.
  • They are ductless

  Exocrine glands

  • Produce a hormone which is not directly released inside of the blood.
  • They have a duct that carries secretion to another place.
• Protein and peptide hormones

  • Are not soluble inside of the membrane so do not enter the cell.

  Steroid hormones

  • Can pass through the membrane and enter the cell.
  • Act upon the DNA inside of the nucleus.
• Adrenal gland:

  • Adrenaline
  • Prepares body for action e.g increased heart rate and also breathing.
• Pancreas:

  • Insulin
  • Promotes glucose by cells, so helps lower blood sugar levels.
  • Glucagon - raises blood sugar levels by converting a carbohydrate store (glycogen) into muscles and the liver in glucose.
• Thyroid:

  • Thyroxine
  • Regulates cell metabolism
  • Regulates calcium absorbption and also use.
• Pituitary:

  • Somatotropin - growth hormone, bone growth
  • Prolactin - Initates production of breast milk
  • LH - Involved in the controlling of the menustral cycle.
  • FSH - Involved in the controlling of the menustral cycle.
  • Oxytocin - Initates contractions of the uterus
  • ADH - Triggers uptake of water from the urine inside of the kidney.
• Each hormone is different from others.

  Some cells have receptors on their plasma membrane (target issues)

  The hormone binds to the receptor and the cells respond to the signal.

  This allows hormones to travel around the body without affecting other cells.
• The centre of the adrenal gland is called the medulla (produces peptide hormones)

  Surronding the medulla is the cortex (produces steroid hormones)
• The function of the adrenal medulla is:

  • Makes and releases adrenaline in response to pain and shock
• Function of adrenal cortex:

  • Uses cholestrol to produce certain steroid hormones

  Mineralocorticoids (eg aldosterone) control the concentration of Na and K inside of the blood.

  Glucocorticoids (eg cortisol) help control the metabolism of the carbohydrates and proteins inside of the liver.
• Adrenaline is a hormone produced by the adrenal gland.

  • Prepares the body for activity
  • Is an amino acid derivative.
  • Cannot enter the target cell/
  • Therefore it must cause an effect without entering the cell.
• ACTION OF ADRENALINE

  
• ACTION OF ADRENALINE PART TWO

  
• ACTION OF ADRENALINE PART THREE

  
• First messenger:

  A hormone that transmits a signal around the body.

  A second messenger:

  Is cAMP which transmits a signal inside of the cell.