Lab 8

Question 1

List the structures: face, palm of hand, back of hand, fingertip, neck, proximal arm by sensitivity according to the class average?

Answer 1

Fingertips, face, palm of hand, neck, back of hand, bicep

Question 2

What are the parts of the reflex arc (or loop):

Answer 2

Stimulus, receptor (sensor), input signal, integration (control) center, output signal, target (effector)

Question 3

What is the stimulus of the reflex arc and what are some examples?

Answer 3

The change in the environment (often for bad). Examples include pressure light, or chemical changes.

Question 4

What is the receptor of the reflex arc and what are some examples?

Answer 4

This is a cell or part of a sensory neuron which detects a stimulus (ie, photoreceptors, muscle spindle,

Question 5

What is the input signal of the reflex arc and what are some examples?

Answer 5

Internal signal that travels along an afferent pathway, towards the integration center.
This is usually the axon of a sensory neuron which conducts action potentials towards the central nervous system.

Question 6

What is the integration center of the reflex arc and what are some examples?

Answer 6

Organ (usually the brain or spinal cord) that processes the information from the input signal and determines what response is needed (if any).
May be as few as one sensory and one motor neuron (monosynaptic), or may also include many neurons (polysynaptic)
For a reflex, the processing that occurs is sub-conscious (you are not aware of it)

Question 7

What is the output signal of the reflex arc and what are some examples?

Answer 7

Internal signal that travels along an efferent pathway
This can be the axons of a motor neuron which conducts an action potential from the CNS to the target or the hormone that is released by a gland towards a target cell

Question 8

What is the target of the reflex arc and what are some examples?

Answer 8

This is what produces a response based on the output signal received.
A muscle could respond by contracting; a gland could respond by secreting.

Question 9

What is the pupillary reflex arc, what type of reflex is it?

Answer 9

Stimulus: light
Receptor: photoreceptors
Input signal: Sensory neurons in the II Optic Nerve
Integration center: The midbrain of the brain
Output signal: The motor neuron of the III Oculomotor nerve
Target: Iris
Response: Pupil constriction
This is both an ipsilateral and a contralateral because the reaction occurred on the same side and the opposite side of the stimulus.

Question 10

What is the patellar reflex arc, what type of reflex is it?

Answer 10

Stimulus: Quadricep stretching
Receptor: Muscle spindle
Input signal: Sensory neurons in the femoral nerve of the lumbar plexus
Integration center: Spinal cord
Output signal: Excited (monosynaptic) motor neurons of the femoral nerve in the lumbar plexus and inhibited (polysynaptic) motor neuron of the sciatic nerve in the sacral plexus
Target: Excited: quadricep Inhibited: hamstring
Response: Contraction of quadricep, relaxation of hamstring –> extension of leg

Ipsilateral because the stimulus was on the right side and so was the response.