What topics reviewed in the first six minutes are you feeling comfortable with? Write at least three.

What topics reviewed in the first six minutes are you still not understanding? Write at least one.

What is an effector?

Order the steps of a reflex arc from first (top) to last (bottom):

1. Motor neuron sends directions on how to react to the stimulus
2. Integration center decodes the signal
3. Receptor senses a stimulus
4. Effector cells respond by contracting or secreting
5. Sensory neuron transmits signal up the PNS to the CNS

Categorize the following definitions and examples

A person can control whether or not a reflex arc will happen

Two students are having a heated argument about reflex arcs.

Student 1 claims that the brain is not involved in reflex arcs because a response can be elicited from the spinal cord.

Student 2 claims that the brain is involved in reflex arcs because you are consciously aware of the reaction.

Which student do you agree with, Student 1 or Student 2? Justify your answer.

Most reflex arc pathways are "three neuron" pathways. The illustration below is that of a typical withdrawl reflex involving three neurons.

Consider what you learned in the 'Peripherap Nervous System' formative as you label (using the terms below) and color (using the key) the diagram in the 'show your work' box. You may not know every single term , but you should be able to use your background knowledge and the process of elimination.

(Note: if you are stuck and don't know what a lot of these terms mean, revisit the 'Peripheral Nervous System' formative rather than googling things!!)

• spinal nerve
• cell body of sensory neuron
• cell body of motor neuron
• synapse
• axon of motor neuron
• axon of sensory neuron
• receptor
• effector
• dendrite of sensory neuron
• posterior root
• anterior root
• posterior root ganglion

Finally, add arrows to show the direction of nerve impulse conduction.

As mentioned above, there are reflex arcs even more simple than the three neuron reflex arc.

The two neuron reflex arc, as shown in the picture below, is what occurs during what we commonly think of as a reflex: the ever famous patellar tendon reflex!

Match the terms below with their location on the diagram.

Brainstorm: Why might it be beneficial that reflex arcs do not require input from the brain to elicit a response? In other words, why do you think we evolved to have reflex arcs that react to stimuli without the brain needing to be involved?

Babies are born with certain reflexes and have them for their entire lives.

Which reflex did you find the most interesting / stuck out to you the most? Why?