Reflex Arc (8)

Question 1

What is a reflex arc?

Answer 1

It is the functional unit of the nervous system. It is the pathway followed by impulses from a receptor to an effector to bring about a reflex action.

Question 2

1. Receptor : 2. Sensory neurons : 3. Connector neuron : 4. Motor neuron : 5. Effector :

Answer 2

1. Responds to stimuli and generates impulses 2. Carries impulses to CNS 3. Acts as reflex centre 4.Carries impulses to an effector organ 5. Brings about change

Question 3

What is a reflex action?

Answer 3

It is a fast, automatic response by an effector organ, ie. a muscle or a gland, to a stimulus received by a receptor organ.

Question 4

Reflexes may be: (2)

Answer 4

-Somatic reflexes which activate skeletal muscles -Autonomic reflexes which activate smooth or cardiac muscle and glands

Question 5

Where may reflex centres may be situated? (2)

Answer 5

-The brain: controlling reflexes such as sneezing, breathing, blinking etc. -The spinal cord: Controlling primitive reflexes such as the knee jerk when tapped below the knee-cap or the immediate withdrawal of a hand or foot from a painful stimulus.

Question 6

What is the significance of the reflex arc? (2)

Answer 6

-Reflex arcs enable the body to respond quickly to a stimulus as very often the higher centres of the brains are not involved -Provide inborn safety mechanisms which serve mainly to protect the body from danger

Question 7

Give examples of reflexes. (4)

Answer 7

-Sneezing to clear the nasal passages of irritants -Blinking when danger threatens the sensitive tissues of the eye -Yawning when there is too much CO2 in the blood -Coughing when food enters the trachea

Question 8

How does a simple reflex arc function? (6)

Answer 8