Structure and function

• Nervous system


  Enables humans to react to their surroundings and to coordinate their behaviour
• Information in the nervous system


  Sent as electrical impulses - electrical signals that pass along nerve cells known as neurones
• Neurones


  • Have a cell body and cytoplasmic extensions called axons and dendrites
  • Some human neurones have axons over a metre in length but only 1-4 micrometres wide
  • This is far more efficient than having multiple neurones to convey information from the CNS to effectors - less time is wasted transferring electrical impulses from one cell to another
  • The axon is insulated by a fatty myelin sheath with small uninsulated sections along it (called nodes) which the impulse jumps along
• Central nervous system (CNS)


  The brain and spinal cord
• Peripheral nervous system (PNS)


  All of the nerves in the body
• Pathway through the nervous system


  1. Stimulus

  2. Receptor

  3. Coordinator

  4. Effector

  5. Response
• The pituitary gland secretes hormones that regulate other endocrine glands, such as growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), oxytocin (OT), antidiuretic hormone (ADH).
• The pancreas produces insulin to lower blood glucose levels when they are high and glucagon to raise them when low.
• The hypothalamus is the control centre for homeostatic mechanisms.
• The hypothalamus is the control centre for homeostatic mechanisms.
• The hypothalamus regulates many bodily functions including hunger, thirst, sleep, sex drive, mood, body temperature, blood pressure, heart rate, and water balance.
• The hypothalamus regulates many bodily functions including hunger, thirst, sleep, sex drive, mood, body temperature, blood pressure, heart rate, and water balance.
• The hypothalamus also plays a role in controlling the release of certain hormones from the pituitary gland.
• The hypothalamus also plays a role in controlling the release of certain hormones from the pituitary gland.