reflex arcs

Question 1

the nerve pathway shown in the diagram may be regarded as a simple reflex arc. Use the diagram to explain why (1)

Answer 1

only 3 neurones

Question 2

suggest 2 advantages of simple reflexes (2)

Answer 2

don’t have to be learned
can escape from predators
protect against damage to body tissues

Question 3

central nervous system

Answer 3

consists of brain and spinal cord

Question 4

peripheral nervous system

Answer 4

made up of pairs of nerves which originate from the brain or spinal cord

made up of sensory and motor neurones-

sensory neurones- carry impulses from receptor to central nervous system

motor nueorones- carry impulse away from central nervous system and to effector

Question 5

voluntary nervous system

Answer 5

voluntary/conscious actions
impulses transmitted to body muscles

Question 6

autonomic nervous system

Answer 6

involuntary/subconscious actions
impulses transmitted to body glands, smooth muscle and cardiac muscle.

Question 7

what is a reflex?

Answer 7

involuntary response to a sensory stimulus

Question 8

what is a reflex arc?

Answer 8

the sequence of nerve cells involved in reflex- is reflex arc

Question 9

sequence

Answer 9

stimulus- detectable change in environment e.g. hot plate.

receptor- cells which detect change e.g. temperature sensitive cells on the back of your hand
sensory neurone carries impulse from receptor to spinal cord/coordination centre
coordinator- links motor and sensory neurones in the spinal cord
motor neurones- tranmits impulse from coordination to effector

effector- muscle in upper arm, which contracts

response- hand moves away from hot object.

Question 10

benefits of reflex arc

Answer 10

increased speed of transmissions
this is due to few synapses

protects body tissues from damage
doesn’t have to be learnt.