Proprioception Flashcards

1
Q

What are proprioceptors?

A

Mechanoreceptors that signal body or limb position

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2
Q

Give three examples of proprioceptors

A

Muscle spindles- monitor muscle length and rate of change of muscle length - control reflexes and voluntary movements
Golgi tendon organs - monitor tension on muscles
Joint receptors - Monitor joint angle, rate of angular movement, and tension on the joint

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3
Q

Which proprioceptors are involved with sending sensory information for spinal cord reflexes?

A

Golgi tendon organs and muscle spindles

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4
Q

What is a muscle spindle?

A

Intrafusal fibres with special sensory and motor innervation contained within a capsule, they lie in parallel with extrafusal muscle fibres

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5
Q

What are the two different types of intrafusal fibre?

A

Nuclear bag fibres - bag shaped, nuclei are all grouped together
Nuclear chain fibres - nuclei are lined up in a chain

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6
Q

What is contained at the ends of the muscle spindle?

A

Sacromeres

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7
Q

What do gamma motoneurones innervate?

A

Innervate ends of intrafusal fibres which contract

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8
Q

What do alpha motoneurones innervate?

A

The extrafusal muscle fibres, they are larger than gamma motoneurones

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9
Q

How are regenerative action potentials in the muscle spindles created?

A

Muscle stretch stimulates the stretch receptors, stretch sensitive ion channel opens causing local generator potential - causing regenerative action potentials

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10
Q

Stretch receptors can monitor the rate of change of muscle length, how is this done

A

The rate of action potential formation reflects the velocity of change of muscle length

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11
Q

How is muscle length determined by the muscle stretch receptors?

A

The resting rate of action potential formation at one muscle length will be different to the resting rate of action potential formation at another length

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12
Q

How can spindle discharge be increased?

A

Stretching the agonnist

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13
Q

Describe the structure of the golgi tendon organ

A

Nerve endings mingle with tendon bundles at the end of the muscle

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14
Q

How are golgi tendon organs activated?

A

Contraction of the muscle, passive stretch doesn’t affect them much

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15
Q

Are GTO’s in series or parallel with the muscle?

A

Series

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16
Q

Which proprioceptors are activated during isometric contraction?

A

Only GTO’s since tension is increased but length of the muscle is kept constant

17
Q

What is the purpose of gamma motor neurones?

A

Makes the intrafusal muscle contract in time with the extrafusal muscle, this restores sensitivity of the central part of the intrafusal fibres at a new muscle length - maintains spindle sensitivity