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Cells to systems > Lecture 20 > Flashcards

Lecture 20 Flashcards

1
Q

What provide afferent information essential for controlling muscle activity

A

Muscle spindles and the Golgi tendon organs

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2
Q

What are the proprioceptors in muscles

A 
– Golgi Tendon Organs
• Present in tendons
• Report muscle tension development
– Muscle Spindles
• Embedded within muscle
• Report muscle position, “Stretch”
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3
Q

How are the information for control of muscle activity use

A
  1. Appraisal of motor areas of the brain about
    muscle length and tension.
  2. Control of muscle length and tension in a
    negative-feedback fashion by means of local
    spinal reflexes
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4
Q

How are the motor neuron influenced

A
  1. Local reflex circuitry
  2. Descending pathways
    from the brain stem
    and cerebral cortex
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5
Q

What are the components of a simple reflex

A 
-Integration centre
(interneuron)
-Efferent arm (output)
-Response element
-Sensor (receptor)
-Afferent arm (input)
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6
Q

What are interneurons

A

the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS)

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7
Q

Why most descending synaptic input does not go

directly to motor neurons

A

because information have to return to interneuron
• Synapse with interneurons which synapse
with motor neurons
• 90% of spinal cord neurons
• Integrate input from higher centres,
peripheral receptors and other interneuronshe interneuron first

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8
Q

Afferent fibres carry information from sensory

receptors in three sources

A
  1. In skeletal muscles controlled by motor
    neurons
  2. In other nearby muscles, especially
    antagonists
  3. In the tendons, joints, and skin of body parts
    affected by muscle action
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9
Q

What are muscle spindle located at

A

located within fleshy part of
muscle
• Intrafusal fibers parallel to
extrafusal fibers

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10
Q

Are muscle spindle contractible

A

• Noncontractile central portion

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11
Q

What do the muscle spindle detect

A
  • rate of change at which the
    muscle fibers are stretched
  • changes in length of muscle fibers
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12
Q

What is the role on muscle spindle

A

• aids in coordination and

efficiency of muscle contraction

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13
Q

What are the types of muscle spindle fibres

A
  • Nuclear bag fibres

* Nuclear chain fibres

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14
Q

What is a Nuclear bag fibres

A

– Large number nuclei
packed into mid-portion
– Sense onset of stretch

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15
Q

What is a Nuclear chain fibres

A

– Nuclei in longitudinal
row
– Sense sustained stretch

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16
Q

How are the muscle spindles activated

A

Both are activated with

rapid stretch

17
Q

What is the Efferent neuron which
innervates intrafusal
fibres

A

gamma (γ)

motor neuron

18
Q

What is the Extrafusal fibres

A

alpha

(α) motor neuron

19
Q

How are muscle spindle attached

A

by connective
tissue in parallel to the
extrafusal fibres.

20
Q

Can external force activate the muscle spindle

A 
yes, External force
stretching the muscle
also stretches the
intrafusal fibres
activating their receptor
endings
21
Q

How are the information sent

A

in frequencies, the more stretched or faster is it, the higher the frequency in signals. The more or the faster the muscle is stretched, the greater the rate of receptor firing

22
Q

What does sudden stretch of a muscle result in

A
  1. Muscle spindles detect stretch of the muscle
  2. Sensory neurons conduct action potentials to the spinal cord
  3. Sensory neurons synapse direct with alpha motor neurons
  4. Alpha motor neurons conduct action potential to the muscle, causing it to contract and resist being stretched.
23
Q

What happen during The stretch, or myotactic, reflex

A

– Produces rapid corrections of motor output in the
moment to moment control of movement
– Forms the basis for postural reflexes to maintain
body position.

24
Q

What is the Golgi Tendon Organs located at

A

located at junction of tendon and

muscle

25
Q

what does the Golgi Tendon Organs detect

A

• detects:

  • force of muscle contraction
  • tension applied to tendon
26
Q

What is the role of golgi tendon organ

A 
• protects tendon and muscle from
excessive tension
• Muscle contraction stretches the
GTO and generates AP
• Greater the force of contraction
higher firing rate
27
Q

What is Golgi Tendon Organs made of

A

A large diameter myelinated type

1b axon arises from each GTO

28
Q

What is the tendon reflex like

A
  1. increased tension stimulates sensory receptor (tendon)
  2. Sensory neuron excited
  3. Within intergrating center (spinal cord), sensory neuron activates inhibitory interneuron
  4. Motor neuron inhibited
  5. effector (muscle attached to same tendon) relaxes and relieves excess tension
29
Q

What is the main role of a tendon organ

A

monitor tension

30
Q

what is Reciprocal Innervation

A

where sign sent of no reponse to the opposite muscle to not counteract it

Cells to systems (25 decks)

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