CBSE – 10th Standard Science

class 10 chapter 7 – Control and Coordination

Control and Coordination

  • Control and coordination are the functions of the nervous system and hormones in our bodies.
  • The responses of the nervous system can be classified as reflex action, voluntary action or involuntary action.
  • The nervous system uses electrical impulses to transmit messages.
  • The nervous system gets information from our sense organs and acts through our muscles.
  • Chemical coordination is seen in both plants and animals.
  • Hormones produced in one part of an organism move to another part to achieve the desired effect.
  • A feedback mechanism regulates the action of the hormones.


In animals, such control and coordination are provided by nervous and muscular tissues. Touching a hot object is an urgent and dangerous situation for us. They need to detect it,and respond to it.  All information from our environment is detected by the specialised tips of some nerve cells. These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so on. So gustatory receptors will detect taste while olfactory receptors will detect smell



Reflex Actions



Human Brain

  • The communication between the central nervous system and the other parts of the body is facilitated by the peripheral nervous system consisting of cranial nerves arising from the brain and spinal nerves arising from the spinal cord.
  • The brain has three such major parts or regions,
    • fore-brain,mid-brain& hind-brain.
  • The fore-brain is the main thinking part of the brain. It has regions which receive sensory impulses from various receptors. Separate areas of the fore-brain are specialised for hearing, smell, sight and so on. The sensation of feeling full is because of a centre associated with hunger, which is in a separate part of the fore-brain.
  • So, in between the simple reflex actions like change in the size of the pupil, and the thought out actions such as moving a chair, there is another set of muscle movements over which we do not have any thinking control. Many of these involuntary actions are controlled by the mid-brain and hind-brain.
  • All these involuntary actions including blood pressure, salivation and vomiting are controlled by the medulla in the hind-brain.
  • Think about activities like walking in a straight line, riding a bicycle,picking up a pencil. These are possible due to a part of the hind-brain called the cerebellum. It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.






Plants do not have a nervous system or an endocrine system.Responses to stimuli in palnts are coordinated by hormones.

Hormones act as chemical messengers which enable plants to respond to many factors, such as light,gravity,water and temperature


Movement Due to Growth

  • When growing plants detect light, a hormone called auxin, synthesised
  • at the shoot tip, helps the cells to grow longer. When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot.
  • Gibberellins which, like auxins, help in the growth of the stem.
  • Cytokinins promote cell division,and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds. These are examples of plant hormones that help in promoting growth.
  • Abscisic acid is one example of a hormone which inhibits growth. Its effects include wilting of leaves.