Edexcel IGCSE Biology: Double Science 复习笔记 2.10.5 Co-ordination Systems in Humans

Edexcel IGCSE Biology: Double Science 复习笔记 2.10.5 Co-ordination Systems in Humans

The Human Nervous System & Endocrine System


  • There are two different control systems in humans that work together to help us respond to stimuli. These are:
    • The nervous system
    • The hormonal system (also known as the endocrine system)


  • Changes in our external environment or in the internal environment of our bodies act as stimuli
  • The nervous and hormonal systems coordinate a suitable response to these stimuli
  • This allows us to make sense of our surroundings, to respond to the changes that occur in our surroundings and coordinate and regulate body functions



The nervous system

  • Information is sent through the nervous system as electrical impulses – these are electrical signals that pass along nerve cells known as neurones
  • These impulses travel along neurones at very high speeds (up to 100 metres per second)
  • This allows rapid responses to stimuli (e.g. the withdrawal reflex that causes you to move your hand away extremely quickly when it touches a flame)
  • The nervous system coordinates the activities of sensory receptors (eg. those in the eye), decision-making centres in the central nervous system (CNS), and effectors such as muscles and glands
  • The nervous system is used to control functions that need instant (or very rapid) responses






The human nervous system




The endocrine system

  • Information is sent through the endocrine (hormonal) system as chemical substances known as hormones
  • Hormones are carried by the blood and can therefore circulate around the whole body
  • Hormones transmit information from one part of the organism to another and bring about a change (they provide a signal that triggers a response)
  • They alter the activity of one or more specific target organs
  • Hormones are used to control functions that do not need instant responses
  • Hormones are produced by endocrine glands
  • The endocrine glands that produce hormones in animals are known collectively as the endocrine system
    • A gland is a group of cells that produces and releases one or more substances (a process known as secretion)





Features of the Nervous System and the Endocrine System Table