NS 3 - Reflexes

Question 1

List and briefly explain 2 types of reflex arcs

Answer 1

Ipsilateral = same side as stim

Crossed extensor= opp side to stim

Question 2

List 5 steps in a neural reflex

Answer 2

1) arrival of stim that activates receptor. Physical or chem changes
2) activation sense neuron via gp
3) IP by PoSyn cell triggered by NT
4) activation of motor neuron by AP
5) response of peripheral effector triggered by NT

Question 3

Explain early dev

Answer 3

Innate

• basic neural reflex
• before birth

Acquired

• rapid, automatic
• learned motor patterns
• reinforced by practice

Question 4

Explain type motor response

Answer 4

Somatic

• involve NS control
• tendon reflex eg: patellar reflex

Visceral

• uses systems other than just muscle
• automatic reflex

Question 5

Explain complexity of neural circuit

Answer 5

Mono synaptic
- sense neuron synapses directly onto motor neuron

Poly synaptic
- at least 1 inter neuron b/w sense and motor neurons

Question 6

Explain site of ip

Answer 6

Spinal
- monosynaptic = least delay bw input and output, receptor is muscle spindle, stretch reflex (babinkski)

• poly synaptic = prod EPSP or IPSP, interneurons control more than 1 muscle group
• inter segmental = interaction of many segments, highly variable motor response

Cranial

Question 7

Explain the tendon reflex

Answer 7

Sensory receptors

Prevents skeletal muscle from developing tension and tearing tendon

Question 8

Explain the withdrawal reflex

Answer 8

Flexor reflex

Move away from stim

Strength depends on intensity and location of stim

Question 9

Explain postural reflex

Answer 9

Stretch reflex

Automatic balance

Muscle responds by contraction

Maintain upright position