A&P Practical 1 - Reflexology

Reflex Arc Components (5 of them)

Reflex Arc Components (5 of them)

1. Receptor

2. Sensory Neuron

3. Integration Center

4. Motor Neuron

5. Effector

   (Figure 21.1)

Receptor (Reflex Arc)

The site of stimulus action

Sensory Neuron (Reflex Arc)

Sends afferent impulses to the Central Nervous System

Integration Center (Reflex Arc)

★Integrates the information from the sensory neuron to the motor neuron

• A synapse between a sensory neuron & a motor neuron (monosynpatic reflex)

• One or more interneurons synapsing to form the integration center (Polysynaptic reflex)

Motor Neuron (Reflex Arc)

Conducts efferent impulses from the integration center to an effector organ

Effector (Reflex Arc)

A muscle fiber or gland cell, response to efferent impulses by contracting or secreting

Monosynaptic Reflex Arc

A single synapse between a sensory neuron & a motor neuron

• Ex: Patella Reflex

  (Figure 21.2)

Polysynaptic Reflex Arc

Involves one or more interneurons synapsing to form the integration center

• Ex: Flexor reflex

  (Figure 21.2)

Patellar Reflex

A kick is seen in response to a tap on the lower patella.

What muscle contracts in the patellar reflex?

Quadricep Femoris

What nerve carries the afferent & efferent impulses in the patellar reflex?

Femoral Nerve

How does distraction play into the patellar reflex?

No effect

How does exercise play into the patellar reflex?

The more exercise, the less of a reflex is seen from the patellar reflex

• This is due to the muscles being tired and worn out

Calcaneal Tendon Reflex

When the Achilles tendon is tapped while the foot is dorsiflexed (pointed upwards), the foot will plantar-flex (point downwards)

Plantar Reflex (Babinski)

An object is dragged from the base of the heel towards the top of the foot, causing the toes to curl in (for a healthy adult) or the toes to fan out (for a healthy baby)

Positive Babinski

Toes fan out

• Bad for adults

• Good for babies

Negative Babinski

Toes curl in

• Good for adults

• Bad for babies

Pupillary Reflex

When light is shined into one pupil, both pupils will contract

• This is a function of the sympathetic nervous system to let in less light to the pupils and get a better view

• This indicates that the nerve pathways of both the eyes converge for this reflex

Ciliospinal Reflex

When the back of the neck is touched on one side, the corresponding side’s pupil will dilate

• This indicated that the nerve pathways of both eyes do not converge for this reflex

Suggested Questions for Reflexology

1, 2, 6, 7, 9, 11, 20, 21