Chapter 3: Coordination and Response (F5)




  • The nervous system and the endocrine system are responsible for coordination in the human body.
  • The three main components in the nervous system are the sensory receptors, the central nervous system and the effector.
  • The sensory receptors detect information in and around the body and relay the information to the central nervous system via the afferent neurones.
  • The central nervous system then integrates the information and relays the response to the effector via the efferent neurones.
  • The effectors are muscles and gland cells.
  • The transmission of information along neurones is by nerve impulses.
  • When an impulse reaches a synaptic terminal, the transmission of information across the synapse is via chemical messengers called neurotransmitters.
  • The brain is made up of cerebrum, cerebellum and medulla oblongata.
  • The cerebral cortex of the cerebrum govern voluntary action involving the skeletal muscles.
  • The spinal cord govern involuntary action.
  • The autonomic nervous system governs involuntary action which involves smooth muscles, cardiac muscles and glands.
  • Diseases associated with disorders of the central nervous system include Parkinson's disease and Alzheimer disease.
  • The endocrine system consists of endocrine glands which produce chemical substances called hormones.
  • Hormones diffuse directly into the blood and are transported by blood to specific target organs.
  • Hormones are required in small quantities.
  • The pituitary gland is the master gland that secretes several hormones that control other endocrine glands.
  • Some examples of these hormones are TSH, LH and ACTH.
  • Hormones function in reproduction, growth and homeostasis.
  • The nervous system and the endocrine system work together to maintain a homeostatic condition in the body.
  • An imbalance of hormones can cause dwarfism, gigantism etc.
  • The maintenance of a relatively constant internal environment is known as homeostasis.
  • Osmoregulation is a process whereby the osmotic pressure of the internal environment is regulated to an optimal level.
  • The kidney helps regulate the balance of water and salt in the body.
  • The regulation of blood osmotic pressure, glucose level and body temperature occurs via negative feedback mechanism.
  • Insulin and glucagon are the two hormones involved in the regulation of blood glucose level.
  • Body temperature is regulated by the thermoregulatory centre in the hypothalamus.
  • The thermoregulatory centre in the hypothalamus regulates the responses of several effectors including the erector pili muscles of the skin, the adrenal glands, the smooth muscles in arterioles, sweat glands and the skeletal muscles.
  • Drugs and alcohol affect the nervous system and endocrine system.
  • We should practise a healthy lifestyle by abstaining from drugs and alcohol.
  • Plants have hormones that regulate their growth and development.
  • Plant hormones are called phytohormones.
  • Auxins promote cell elongation in the shoot.
  • Ethylene speeds up ripening of fruits.

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