Nervous and Endocrine system

• Nervous system: Specialized network of cells in the human body that is our primary internal communication system. It is based on electrical and chemical signals.
• What are the two main functions of the nervous system?

  1. To collect, process and respond to information in the environment.
  2. To coordinate the working of different organs and cells in the body.
• What are the two subsystems of the nervous system?

  The central nervous system (CNS) and The peripheral nervous system (PNS)
• What are the two main subsystems of the central nervous system?


  The brain and spinal cord
• Central nervous system: Origin of all complex commands and decisions.
• Brain: Centre of all conscious awareness. It is highly developed in humans and is what distinguishes our higher mental functions from other creatures. It is divided into two hemispheres.
• Spinal cord: Extension of the brain, passes messages to and from the brain and connects nerves to the PNS. It is also responsible for reflex actions such as pulling your hand away from a hot plate.
• Peripheral nervous system: Sends information to the CNS from the outside world , and transmits messages from the CNS to muscles and glands in the body.
• What are the two subdivisions of the peripheral nervous system?


  Autonomic nervous system and the Somatic nervous system
• Somatic nervous system: Transmits information from the receptor cells in the sense organs to the CNS. It also governs muscle movement due to information being sent from the CNS.
• Autonomic nervous system: Transmits information to and from internal bodily organs governing vital functions automatically such as breathing or heartrate.
• What are the two subdivisions of the peripheral nervous system?


  Sympathetic nervous system and the parasympathetic nervous system.
• Parasympathetic nervous system:  network of nerves that relaxes your body after periods of danger. It is responsible for 'rest and digest' bodily functions.
• Sympathetic nervous system: Prepares your body for danger, responsible for 'flight or fight' response.
• Endocrine system: One of the body's major information systems that instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs. Communicates via chemicals.
• The endocrine system works slower than the nervous system however its affects are more widespread and powerful.
• The pituitary gland: Located in the brain and is often called the 'master gland' because it controls the release of hormones from all the other glands in the body.
• What are the different glands in the body?

  • Hypothalamus
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal - Produces adrenaline
  • Pancreas
  • Ovaries
  • Testes
• Gland: An organ in the body that synthesizes substances such as hormones.
• Hormone: A biochemical substance that circulates in the blood but only affects the target organs. They are produces in large quantities and have powerful effects but disappear quickly.
• Fight or flight response: The way animals respond when stressed. The body becomes physiologically aroused in readiness to fight or run.
• Adrenaline: A hormone produced by the adrenal glands which is a part of the human body's immediate stress response. Causes the body to go into the sympathetic state.
• Flight or fight response steps:

  1. The hypothalamus activates the pituitary gland.
  2. This triggers activity in the sympathetic branch of the ANS.
  3. The ANS changes from its normal resting state to the sympathetic state.
  4. Adrenaline is released, triggering changes to the body such as increased heart rate. Creating the necessary arousal for the fight or flight response.
  5. Once the threat has passed , the body returns to its normal resting state and could go through the 'rest and digest' response.
• Examples of the sympathetic state:

  • Increased heart rate
  • Increased breathing rate
  • Dilates pupils