Nervous and Endocrine system

• Nervous system= central nervous system + peripheral nervous system
• Central nervous system (CNS) = brain + spinal cord
• Peripheral nervous system (PNS) = sends information to the CNS from the outside world and transmits messages from the CNS to muscles and glands in the body
• Somatic nervous system = transmits information from receptor cells in the sense organs to the central nervous system. It also receives information from the CNS that directs muscles to act.
• Autonomic nervous system = transmits information to and from internal bodily organs. It operates involuntary (it is automatic) and it has two branches: the sympathetic and parasympathetic nervous systems.
• The nervous system has two main functions:

  • to collect, process and respond to information in the environment
  • to co-ordinate the working of different organs and cells in the body
• Autonomic nervous system = governs vital functions in the body such as breathing, heart rate, digestion and stress response
• Somatic nervous system = controls muscle movement and receives information from sensory receptors
• Endocrine system = instructs glands to release hormones directly into the bloodstream to be carried towards target organs
• The endocrine system acts much more slowly than the nervous system but has very widespread and powerful effects.
• Pituitary gland = 'master gland' because it control the release of hormones from all the other endocrine glands in the body
• Fight or flight:

  • Hypothalamus triggers activity in the sympathetic branch of the autonomic system
  • ANS changes from its normal resting state to the physiologically aroused, sympathetic state
  • Adrenaline is released from the adrenal gland into the bloodstream
  • Adrenaline triggers physiological changes in the body which creates the physiological arousal necessary for the fight or flight response
• Fight or flight:

  Once the threat has passed, the parasympathetic nervous system returns the body to its resting state. The parasympathetic branch of the ANS works in opposition to the sympathetic nervous system- it acts as a 'brake' and reduces the activity of the body. This is known as the rest and digest response.
• Sympathetic state:

  • increased heart rate
  • increased breathing rate
  • dilated pupils
  • inhibited digestion
  • inhibited saliva production