Hormones and nerves

• Hormones are chemical substances produced by glands and carried in the bloodstream to specific target organs in the body
• An example is adrenaline, released by the adrenal gland, which increases heart rate
• Hormones are destroyed by the liver after use
• Hormones control the body with slower effects compared to the nervous system, but they last longer
• Nervous control is electrical and fast, while hormonal control is chemical and slower
• Nervous transmission is by nerve cells, while hormonal transmission is through the bloodstream
• Nervous effectors are muscles or glands, while hormonal effectors are target cells in specific tissues
• Nervous response is muscle contraction or secretion, while hormonal response is chemical change
• Nervous response is rapid and short-lived, while hormonal response is slower and long-lasting
• The pituitary gland in the brain is known as the 'master gland' and releases hormones in response to the body's condition
• The pituitary gland can stimulate other glands to release different hormones and bring about effects
• The body produces various hormones that travel in the bloodstream and affect different organs or cells
• Important hormones include ADH, adrenaline, and insulin
• ADH:

  • Source: Pituitary gland
  • Organ: Kidneys
  • Role: Controlling water content of blood
  • Effect: Increases reabsorption of water by collecting ducts
• Adrenaline:

  • Source: Adrenal glands
  • Organ: Several targets including respiratory and circulatory systems
  • Role: Preparation for 'fight or flight'
  • Effect: Increases breathing rate, heart rate, blood flow to muscles, conversion of glycogen to glucose
• Insulin:

  • Source: Pancreas
  • Organ: Liver
  • Role: Controlling blood glucose levels
  • Effect: Increases conversion of glucose into glycogen for storage