Unit 5: The nervous and endocrine systems                    1   2   3   4   5

2. The nervous system

a) Functions of the nervous system:

• It receives the sensorial information from sense organs.
• It interprets this information.
• It elaborates appropriate responses.
• It transmits orders to effector organs which perform the response.
• It coordinates the operation of all organs.
• It carries out the intellectual and mental functions.
• It is responsible for the feelings and the emotions.

b)  General organisation of the nervous system:

The nervous system is organised following this sketch:

The elements which participate are:

• Receptor. It is a cell that is able to perceive the stimulus, transforms it in nerve impulse and transmits it to other nerve cell. Sometimes these cells are grouped forming sense organs.  Each receptor is sensitive to a specific stimulus (light, sound, pressure, pain…)

• Nerves. They are formed by nerve cells which transmit nerve impulses from receptors to nerve centres (sensitive nerves) or from them to effectors (motor nerves).

• Nerve centre. It is the organ which receives the information, processes it and elaborates the response.

• Effector. It is the organ which performs the response. There are two types of effectors:
• • Muscles. They produce a motor response (a movement).
  • Glands. They produce a secretory response (a substance’s secretion)

c) Structure of the nervous system:

Our nervous system is divided into two subsystems:

• Central nervous system. It is formed by the nerve centres (Encephalon and spinal cord)
• Peripheral nervous system. It is formed by the nerves.
• • Somatic.  It controls the voluntary movement of skeletal muscles
  • Autonomic. It controls self-regulated actions of internal organs and glands.
  • • Sympathetic
    • Parasympathetic

2.1. Imagine that you are going to cross the street. You get distracted

        and do not look before crossing. Suddenly you hear a claxon.

        Immediately you go back to the pavement.

a. What are the stimulus and the response in this example?

b. What are the sensorial and the effector organs implicated?

c. What nerve centre receives the sensorial information, elaborates the response

    and transmits it to the effector? 

2.2. Listen and identify what component of the nervous system funcional sketch

        is described: