The nervous system - biopsychology

• the key features of the nervous system

  the nervous system is a specialised network of cells and our primary communication system. it has two main functions:

  1. to collect, process, and respond to information in the environment.
  2. to co-ordinate the working of different organs and cells in the body.

  it is divided into the central nervous system and the peripheral nervous system,
• the structure and function of the central nervous system (CNS)

  • the CNS is made up of the brain and the spinal cord.
  • the brain is the centre of all conscious awareness.
  • the outer layer of the brain, the cerebral cortex, is highly developed in humans and is what distinguished our higher mental functions from those of animals.
  • the spinal cord is an extension of the brain and is responsible for reflex actions.
  • it passes messages to and from the brain and connects nerves to the PNS (peripheral nervous system).
• the structure and function of the PNS

  • the PNS transmits messages, via millions of neurons, to and from the nervous system.
  • the PNS is further sub-divided into the autonomic nervous system (ANS) and the somatic nervous system (SNS).
  • the ANS governs vital functions in the body, such as breathing, heart rate, digestion, sexual arousal, and stress responses.
  • the SNS controls muscle movement and receives information from sensory receptors.
• the key features of the endocrine system

  the endocrine system works alongside the nervous system to control vital functions in the body through the action of hormones.

  it works much more slowly than the nervous system but has widespread and powerful effects.
• glands

  glands are organs in the body that produce hormones.

  the major endocrine gland is the pituitary gland, located in the brain. it is called the master gland because it controls the release of hormones from all the other endocrine glands in the body.
• hormones

  hormones are secreted in the bloodstream and affect any cell in the body that has a receptor for that particular hormone.

  for example, thyroxine produced by the thyroid gland affects cells in the heart and also cells throughout the body which increase metabolic rates. this in turn affects growth rates.
• Fight or flight response

  1. Stressor perceived

  2. Hypothalamus triggers activity in sympathetic brain of ANS

  3. ANS changes from parasympathetic to sympathetic state

  4. Stress hormone adrenaline released from adrenal medulla

  5. Adrenaline triggers physiological changes (increased heart rate, dilated pupils, decreased saliva production)

  6. Threat passes, parasympathetic system returns to resting 'rest and digest' state
• The fight or flight response is the physiologically aroused sympathetic state