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BIOL21332 - Motor Systems > Lecture 6 - Spinal interneurons and spinal reflexes > Flashcards

Lecture 6 - Spinal interneurons and spinal reflexes Flashcards

1
Q

Which layers of the spinal cord are the dorsal horn?

A

Layers 1-6

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2
Q

Which layers of the spinal cord are intermediate?

A

Layer 7-8

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3
Q

Which layer of the spinal cord are the ventral horn?

A

Layer 8

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4
Q

What part of the spinal cord is linked to sensory information?

A

Dorsal horn

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5
Q

Which part of the spinal cord is linked to the interneurons?

A

Intermediate part

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6
Q

Which part of the spinal cord is linked to motor neurons?

A

Ventral horn

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7
Q

What is the role of spinal interneurons?

A
  • Act as convergence of inputs
  • Mainly inhibitory
  • Some excitatory
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8
Q

What is the reflex arc?

A

The mechanisms involved in generating a reflex to a stimulus

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9
Q

What is a reflex?

A

An involuntary coordinated pattern of muscle contraction and relaxation elicited by a peripheral stimulus.

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10
Q

What can supra-spinal centres modulate?

A

Spinal reflexes

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11
Q

What is a myotatic reflex?

A
  • Stretch reflex

- Muscle contracts in response to its lengthening

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12
Q

What is the sensory receptor in the stretch reflex?

A

Muscle spindle primary ending

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13
Q

What is the function of the stretch reflex?

A
  • Resist unwanted lengthening

- Negative feedback control of muscle contractions

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14
Q

How are inhibitory interneurons activated at rest?

A

By golgi tedon organs

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15
Q

What happens when inhibitory interneurons are inhibited by other interneurons?

A
  • Motor neurons are activated

- Muscle contracts

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16
Q

What is the function of the tendon reflex?

A
  • Resists unwanted muscle lengthening
  • Stabilises joints
  • Maintain up-right posture
17
Q

What initiates the withdrawal reflex?

A
  • Painful stimuli
18
Q

What are the 2 branches of the withdrawal reflex? [2]

A
  • Withdrawal /flexion of stimulated limb

- Crossed-extension of contralateral limb

19
Q

What are Renshaw limbs?

A

Inhibitory interneurons

20
Q

What is the role of Renshaw cells?

A

Act as a negative feedback control mechanism

21
Q

How are Renshaw cells activated?

A

They receive an excitatory signal from the motor neuron that innervates the muscle during a reflex

22
Q

What happens when the stretch reflex is hypoactive/absent?

A
  • Disorders interupting the relfex arc

- CNS lesions (spinal shock)

23
Q

What happens when the stretch reflex is hyperactive?

A
  • Cerebral palsy, spasticity etc

- CNS lesions

BIOL21332 - Motor Systems (21 decks)

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