Human nervous system

Question 1

What is the function of the nervous system?

Answer 1

The nervous system allows the body to react to its surroundings and coordinate an appropriate response.

Question 2

How does a stimulus lead to a response being carried out by the body?

Answer 2

• Stimulus is converted into an electrical impulse by the receptors.
• The electrical impulse passes along the sensory neurons to the central nervous system (CNS).
• The CNS coordinates an appropriate response and an electrical impulse is sent along the motor neurons to the effector, which carries out the response.

Question 3

Where is body temperature controlled in the body?

Answer 3

Body temperature is controlled by the thermoregulatory centre in the hypothalamus of the brain.

Question 4

How is temperature monitored by the body?

Answer 4

• Thermoregulatory centre has receptors sensitive to blood temperature.
• Skin has receptors sensitive to skin temperature - sends impulses to thermoregulatory centre.

Question 5

What physiological changes occur when the body temperature is too high?

Answer 5

• Vasodilation: blood vessels near the surface of the skin dilate (expand) - more heat is radiated away.
• Sweating: evaporation of water takes away heat energy from the surface of the skin.

Question 6

What physiological changes when the body temperature is too low?

Answer 6

• Vasoconstriction: blood vessels near the surface of the skin constrict (become narrow) - less heat is radiated away.
• Shivering: respiration allows the muscles to contract. It is an exothermic process, so heat energy is released.
• Sweating stops.