IB Biology: C3.1-Reflex Actions and Reflex Arc

Front

What is a reflex action?

Back

A reflex action is a rapid, automatic or involuntary response to a specific stimulus.

Front

What is a reflex arc?

Back

A reflex arc is the path (including participating cells) along which impulses travel in a reflex action.

Front

What is the purpose of reflex actions?

Back

Reflex actions provide a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors aimed at protecting the body from harm.

Front

What is an example of involuntary responses with skeletal muscles as the effector?

Back

A reflex arc is an example of involuntary responses with skeletal muscles as the effector.

Front

What happens when you touch a sharp pin with your finger?

Back

Receptors initiate afferent action potentials that travel through the hand to the spinal cord through one of the spinal nerves.

Front

What occurs when the afferent neuron enters the spinal cord?

Back

The afferent neuron synapses with an interneuron in the grey matter.

Front

What is the role of the interneuron or relay neuron in a reflex arc?

Back

The interneuron or relay neuron synapses with a motor neuron in the grey matter.

Front

What happens after the motor neuron is activated in a reflex arc?

Back

The action potentials passed to the motor neuron go directly to the arm muscles (effector), causing them to contract and pull the finger away from the sharp pin.