Reflex Arc

Question 1

What are reflexes?

Answer 1

Fast, innate, involuntary actions which use unconcious parts of the brain to prevent our body from damage to increase survival chances

Question 2

What is the general structure of the reflex arc?

Answer 2

Stimuli detected by receptor, to sensory neurone, to relay neurone, to motor neurone, to effector

Question 3

Explain the 5 steps in testing a knee jerk reflex

Answer 3

1. Tap underneath the kneecap, causes the patellar tendon (quad) to stretch which stretches the quad muscle
2. Receptors detect a muscle stretch
3. A nerve impulse is sent along teh sensory neurone to the spinal chord (CNS)
4. Sensory neurone connects with the motor neurone, takes impulse to the extensor muscle (quads)
5. Relay neurone inhibits motor neurone of flexor muscle (hamstring) so no impulse is carries here
6. Extensor muslce relaxes, flexor relaxes and leg kicks out to walk

Question 4

What type of reflex is the knee jerk reflex?

Answer 4

Spinal reflex, as it involves the spinal chord

Question 5

Explain the 5 steps of the blinking reflex

Answer 5

1. Cornea is stimulated/irritated by a light brush/lights
2. Signals impulse along sensory neurone
3. relay neurone in lower brain stem pass impulse along
4. Signal branches off motor neurone to eyelid muscles (orbicularis oculi muscles)
5. Both eyes close as a consensual response

Question 6

What type of reflex is the bliking reflex?

Answer 6

Cranial reflex, as it involves the brain