Reflex Action

Question 1

What is the reflex arc?

What are the five basic components of all reflex arcs:

Answer 1

A reflex is a rapid, involuntary motor response to a stimulus.

The reflex arc has five elements:

• Receptor ► Sensory Neuron ► CNS Integration Center ► Motor neuron ► Effector

Question 2

What is a monosynaptic reflex?

Give an example:

Answer 2

2 Neuron Chain involved:

In simple reflex arcs, the integration center may be a single synapse between a sensory neuron and a motor neuron.

PATELLAR REFLEX (STRETCH REFLEX)

Question 3

What is a polysynaptic reflex?

Give an example

Answer 3

Requires 3 or more sets of neurons

More complex reflex arcs involve multiple synapses with chains of interneurons.

WITHDRAWAL REFLEX (CROSSED-EXTENSOR REFLEXES)

Question 4

Knee Jerk Reflex (stretch reflex)

Answer 4

• helps keep your knees from buckling when you are standing upright.
• important for maintaining muscle tone & adjusting it reflexively
• Monosynaptic & Ipsilateral

Question 5

Flexor or Withdrawal Reflex

Answer 5

• initiated by a painful stimulus and causes automatic withdrawal of the threathened body part from the stimulus.
• protective reflexes important for survival
• Ipsilateral and Polysynaptic