A&P 2.4 stretch reflex, CNS anatomy Flashcards Preview

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Flashcards in A&P 2.4 stretch reflex, CNS anatomy Deck (24)
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0
Q

Stretch reflex

Defined

A

Myotatic reflex - causes the contraction of a skeletal muscle (the effector) in response to stretching the muscle.

Example: knee jerk reflex

7 steps

1
Q

Reflex arc

A

Fast and involuntary action in response to a stimulus
Simplest form of integration
Shortest pathway from a stimulus to a response

7 steps

2
Q

Myotatic

A

Of the muscle

3
Q

Stretch reflex

Knee jerk example

Stimulus

A

Stretch the muscle belly via tap on tendon or muscle

4
Q

Sensory receptor

A

Dendrite or specialized structure that stimulates a dendrite = muscle spindle

5
Q

Sensory neuron

A

Afferent - conducts a nerve impulse from receptor to the CNS

6
Q

Integrating center

A

Sensory neurons synapse (directly with motor neurons therefore are MONOSYNAPTIC)

NO INTERNEURON OR ASSOCIATION NEURON

7
Q

Motor neuron

A

Efferent - conducts a nerve impulse from the CNS to an effector

8
Q

Effector

A

The muscle that was stretched

9
Q

Response

A

Muscle contraction

10
Q

Muscle spindle

Three bullets

A

Specialized structure that stimulates a dendrite

  • PNS subtype: proprioceptors- found in muscles, fascia and tendons
  • cellular characteristics: free nerve ending, simple, encapsulated
  • stimulus: mechanoreceptor- main function is to measure muscle length and respond to sudden or prolonged stretching of muscle spindle fibers
11
Q

MONOSYNAPTIC

A

Only one synapse in the CNS

12
Q

Knee jerk example

Three steps

A
  • Quads are stretched by tapping on the tendon
  • quads are the agonist/prime mover and contract
  • hamstring are the antagonist are inhibited by reciprocal innervation

Ipsilateral reflex- entire reflex from stimulus to response happens on 1 side or the same side of the body

13
Q

Argonist

A

Prime mover

Muscle that’s contracting

14
Q

Antagonist

A

Muscles opposing the contraction/ muscles that do the opposite action at the SAME JOINT

Prime stopper

15
Q

Ipsilateral

A

One side or same side

16
Q

Reciprocal innervation

A

When a stretched muscle contracts during a stretch reflex, antagonist muscles oppose the contraction relax. Reciprocal innervation prevents conflict between opposing muscles and is vital in coordinating body movements. These are motor pathways that excite a muscle and simultaneously inhibit its’ antagonist.

17
Q

Reflexes categorized according to

2 things

A

Effector: Somatic versus visceral

Location of integration: spinal versus cranial

18
Q

Effector

A

Somatic- body(skeletal, muscles, bones, fascia)

Visceral- organs in the abdomen, often G.I tract (example: defication after eating)

19
Q

Location of integration

A

Spinal reflexes - integration in the grey matter of the spinal cord; includes most proprioceptive and pain reflexes are spinal (including stretch reflex)

Cranial reflexes - integration takes place in the brain stem; eye reflex, startled reflex, propriocepative/pain reflex

20
Q

Propriocepative/pain reflex

A

Mostly spinal reflexes unless arising muscles are innervated by cranial nerves

Examples: muscles of the head, face, jaw, SCM, trapezius

21
Q

Startled reflex

A

Looking in the direction of the stimulus

22
Q

Teres minor

A, I, O

A

A - laterally rotate the shoulder, stabilize the head of the humerus in the glenoid cavity

O - upper 2/3 of lateral/axillary border

I - greater tuberercle of the humerus

23
Q

Subscapularis

A, I, O

A

A - medially rotate the shoulder, stabilize the head of the humerus in the glenoid cavity

O - subscapular fossa of the scapula (costal surface of the scapula)

I - lesser tubercle of the humerus