Exam 1: Reflexes

Question 1

What are the 3 types of neuronal pathways?

Answer 1

Convergent pathway

Divergent pathway

Oscillating circuit

Question 2

What are the 3 elements of circuits?

Answer 2

Input: Originate elsewhere and terminate in synapses within the local circuit

Output: send axons to one or more targets

Interneurons: excitatory and inhibitory

Question 3

What are the 4 properties of reflexes?

Answer 3

ž1. Require stimulation

žž2. Quick

žž3. Involuntary

žž4. Stereotyped (predictable)

Question 4

The muscle spindle detects

Answer 4

Muscle stretch

Question 5

Path of muscle stretch reflex:

Sensory nerve originates in the _____ _____ and enters the _____ root of the spinal cord

A branch then goes to the _____ horn of the cord grey matter and synapses with the _____ _____ neurons,

The _____ _____ neurons then send _____ nerve fibers back to the same muscle in which the _____ _____ fiber originated

causing _____ of the stretched muscle to ______ / ______ the stretch

Answer 5

Path of muscle stretch reflex:

Sensory nerve originates in the muscle spindle and enters the dorsal root of the spinal cord

A branch then goes to the anterior horn of the cord grey matter and synapses with the anterior motor neurons

Anterior motor neuron sends motor nerve fibers back to the same muscle in which the muscle spindle fiber originated

causing contraction of the stretched muscle to resist / reverse the stretch

Question 6

The muscle stretch reflex:

is a _____ pathway that permits the _____ _____ time delay

Answer 6

The muscle stretch reflex:

is a monosynaptic pathway that permits the shortest possible time delay

Question 7

Muscle stretch reflex:

An important feature of the stretch reflex is its ability to provide a _____ muscle contraction, which prevents _____ (oscillation or jerkiness)

Signals are transmitted in _____ intensities but the contraction of the muscle is _____

If the _____ _____ _____ is not functioning, then the muscle contraction is _____ during the course of the signal

Answer 7

Muscle stretch reflex:

An important feature of the stretch reflex is its ability to provide a smooth muscle contraction, which prevents clonus (oscillation or jerkiness)

Signals are transmitted in varying intensities but the contraction of the muscle is smooth

If the muscle spindle apparatus is not functioning, then the muscle contraction is jerky during the course of the signal

Question 8

Abnormalities of Muscle stretch reflex:

žDecreased or absent reflex: disruption of the input or output which often occurs in _____ or _____

žžHyper-reflex: _____ _____ neuron lesions: the inhibitory effect is _____

žžAsymmetrical hyper-reflex: reflex not symmetrical between the left and right sides: _____ _____ _____ lesion

Answer 8

Abnormalities of Muscle stretch reflex:

Decreased or absent reflex: disruption of the input or output which often occurs in polyneuropathy or radiculopathy

žžHyper-reflex: upper motor neuron lesions: the inhibitory effect is lessened (output signal usually disrupted)

žžAsymmetrical hyper-reflex: reflex not symmetrical between the left and right sides: upper motor neuron lesion

Question 9

The Golgi tendon organ detects

Answer 9

Muscle tension

Question 10

Golgi tendon reflex:

Golgi tendon organ is an _____ sensory receptor through which _____ _____ fibers pass

Golgi tendon organ is stimulated when the bundle of muscle fibers is “_____” by _____ or _____ the muscle

Answer 10

Golgi tendon reflex:

Golgi tendon organ is an encapsulated sensory receptor through which muscle tendon fibers pass

Golgi tendon organ is stimulated when the bundle of muscle fibers is “tensed” by contracting or stretching the muscle

Question 11

Golgi tendon reflex:

žStimulated by muscle _____ in the connecting muscle

signals are transmitted to the spinal cord to cause an _____ _____ response that _____ the muscle

and an _____ response to _____ the antagonistic muscle

Answer 11

Golgi tendon reflex:

žStimulated by muscle tension in the connecting muscle

signals are transmitted to the spinal cord to cause an inhibitory response that lengthens the muscle (prevents development of too much tension on the muscle)

and an excitatory response to activate the antagonistic muscle

Question 12

Muscle spindle vs Golgi tendon:

The muscle spindle is stimulated when _____

vs

the golgi tendon organ which is stimulated when _____

Answer 12

Muscle spindle vs Golgi tendon:

The muscle spindle is stimulated when stretched

vs

the golgi tendon organ which is stimulated when tensed (it can be tensed by contracting or stretching the muscle!)

Question 13

Muscle spindle vs Golgi tendon:

The muscle spindle pathway _____ the stimulated muscle while reciprocally _____ the antagonist muscle

vs

The golgi tendon organ which _____ the antagonistic muscle while _____ the stimulated muscle

Answer 13

Muscle spindle vs Golgi tendon:

The muscle spindle pathway excites the stimulated muscle while reciprocally inhibiting the antagonist muscle (by damping efferent impulses)

vs

The golgi tendon organ which excites the antagonistic muscle while inhibiting (relaxing) the stimulated muscle

Question 14

Muscle spindle vs Golgi tendon:

The muscle spindle pathway is _____ to give the _____ pathway

vs

The golgi tendon organ pathway which is an _____ _____ with _____ in the spinal cord

Answer 14

Muscle spindle vs Golgi tendon:

The muscle spindle pathway is monosynaptic to give the quickest pathway

vs

The golgi tendon organ pathway which is an inhibitory circuit (negative feedback circuit) with interneurons in the spinal cord

Question 15

Flexor reflex:

žA sensory stimulus from a limb causes the _____ muscles of the limb to _____

žStimulated most powerfully by _____ endings

Answer 15

Flexor reflex:

žA sensory stimulus from a limb causes the flexor muscles of the limb to contract withdrawing the limb from the stimulating object

žStimulated most powerfully by pain endings

ž*Not limited to the limbs. If any part of the body is painfully stimulated this reflex still occurs

Question 16

Flexor reflex to pain:ž

_____ contraction of _____ muscles to withdraw a limb from an injurious stimulus

Painful stimulus applied at the hand

Signal travels into the spinal cord _____ _____ and secondarily to the _____ _____

_____ _____ excite the _____ muscles of the arm and inhibition of _____ muscles

Hand is withdrawn from the painful signal

Answer 16

Flexor reflex to pain:ž

Quick contraction of flexor muscles to withdraw a limb from an injurious stimulus

Painful stimulus applied at the hand

Signal travels into the spinal cord neuronal pool and secondarily to the motor neurons

Motor neurons excite the flexor muscles of the arm and inhibition of relaxer muscles

Hand is withdrawn from the painful signal

Question 17

Flexor reflex:

Is not a _____ pathway

The muscle still _____ after stimulus is released due to _____

Stronger stimulus (like fire) leads to _____ _____

Answer 17

Flexor reflex:

Is not a monosynaptic pathway

The muscle still contracts after stimulus is released due to afterdischarge

Stronger stimulus (like fire) leads to prolonged afterdischarge

Question 18

Crossed extensor reflex:

_____ seconds after a stimulus elicits a _____ reflex in one limb

Signals from the sensory nerve cross to the opposite side of the spinal cord to excite the _____ muscles

so that the opposite limb begins to _____

_____ of the opposite limb can push the entire body away from the object causing pain

Answer 18

Crossed extensor reflex:

0.2 – 0.5 seconds (200-500 milliseconds) after a stimulus elicits a flexor reflex (pain stimulus) one limb

Signals from the sensory nerve cross to the opposite side of the spinal cord to excite the extensor muscles

so that the opposite limb begins to extend

žExtension of the opposite limb can push the entire body away from the object causing pain

Question 19

Crossed extensor reflex:

_____ _____ before the reflex begins

_____ afterdischarge period than the flexor reflex (to _____ _____)

Answer 19

Crossed extensor reflex:

Long latency before the reflex begins (while flexor responds first)

longer afterdischarge period than the flexor reflex (to maintain stablization)

Question 20

Afterdischarge of flexer reflex vs crossed extensor reflex:

Crossed extensor afterdischarge is _____ than the flexor afterdischarge

Answer 20

Afterdischarge of flexer reflex vs crossed extensor reflex:

Crossed extensor afterdischarge is longer than the flexor afterdischarge

Question 21

Superficial Reflexes:

Name 5 superficial reflexes

Answer 21

Superficial Reflexes:

žBiceps jerk reflex

žTriceps jerk reflex

žAbdominal reflex

žAnkle-jerk reflex (plantar reflex)

žCremastric reflex

Question 22

Biceps jerk reflex:

žExaminer places finger on the inside of the _____ _____ over the tendon of the _____ muscle and finger is _____.

The biceps _____ in response and the forearm _____ at the elbow

Answer 22

Biceps jerk reflex:

žExaminer places finger on the inside of the extended elbow over the tendon of the biceps muscle and finger is tapped.

The biceps contracts in response and the forearm flexes at the elbow

Question 23

Triceps jerk reflex:

žTapping the _____ tendon of the triceps muscle close to its _____ near the tip of the _____ elicits this reflex.

The muscle _____ in response, forearm _____ slightly

Answer 23

Triceps jerk reflex:

žTapping the short tendon of the triceps muscle close to its insertion near the tip of the elbow elicits this reflex.

The muscle contracts in response, forearm extends slightly

Question 24

Abdominal reflex:

žExaminer strokes the skin of the abdomen with a _____ _____ from the _____ of abdomen towards the _____ and _____ the umbilicus.

The umbilicus moves _____ the stimulated region

Answer 24

Abdominal reflex:

žExaminer strokes the skin of the abdomen with a dull pin from the side of abdomen towards the midline and above the umbilicus.

The umbilicus moves towards the stimulated region

Question 25

Ankle-jerk reflex (plantar reflex):

Tapping the _____ _____ just _____ its insertion on the _____ elicits this reflex.

The response is plantar _____, produced by _____ of the _____ and _____ muscles

Answer 25

Ankle-jerk reflex (plantar reflex):

žTapping the Achilles tendon just above its insertion on the Calcaneous elicits this reflex.

The response is plantar flexion, produced by contraction of the gastrocnemious and solues muscles

Question 26

Cremastric reflex:

žželicited in males by stroking the _____ _____ of the thigh.

In response, the _____ on the _____ side is elevated by contracting muscles.

Answer 26

Cremastric reflex:

želicited in males by stroking the upper inside of the thigh.

In response, the testis on the same side is elevated by contracting muscles.

Question 27

Somatic Reflexes review:

žReflex: a _____, _____, _____ reaction of a gland or muscle to a stimulus

žSomatic reflexes: are initiated by _____ (e.g golgi tendon) AND _____ that result in skeletal muscle response

žStretch reflex: is the tendency of a muscle to _____ when it is stretched and accompanied by reciprocal _____ of an antagonistic muscle

Answer 27

Somatic Reflexes review:

žReflex: a quick, involuntary, stereotyped reaction of a gland or muscle to a stimulus

žSomatic reflexes: are initiated by proprioceptors (e.g golgi tendon) AND nocipceptors that result in skeletal muscle response

žStretch reflex: is the tendency of a muscle to contract when it is stretched and accompanied by reciprocal inhibition of an antagonistic muscle

Question 28

Somatic Reflexes review:

žžFlexor reflex: is _____ of a limb from an injurious stimulus.

žCrossed Extensor reflex: is _____ of the extensors on one side of the body and _____ of flexors on the other side

žGolgi Tendon reflex: is the _____ of a muscle contraction that occurs when its tendon is _____ _____.

Answer 28

Somatic Reflexes review:

žFlexor reflex: is withdrawal of a limb from an injurious stimulus.

žCrossed Extensor reflex: is contraction of the extensors on one side of the body and contraction of flexors on the other side

žGolgi Tendon reflex: is the inhibition of a muscle contraction that occurs when its tendon is excessively stretched (by detecting muscle tension). This reflex prevents tendon injuries and helps to distribute workload across a muscle

Question 29

Stimulation of sensory fibers innervating a muscle spindle:

A. Will inhibit muscle contraction

B. Will activate an inhibitory interneuron

C. Will activate a motor neuron connected to the muscle

Answer 29

Stimulation of sensory fibers innervating a muscle spindle:

C.

Will activate a motor neuron connected to the muscle

Question 30

The function of the golgi tendon organ is:

A. To sense the length of the muscle tendon in which it is located

B. To transmit muscle stretch information to the brain

C. To sense muscle tension and equalize the contractile force exerted by groups of muscle fibers within a muscle

Answer 30

The function of the golgi tendon organ is:

C.

To sense muscle tension and equalize the contractile force exerted by groups of muscle fibers within a muscle

Question 31

A 4-year-old comes to the pediatrician for her routine check-up. The physician taps the patellar tendon with a small hammer to test the child’s response. Which of the following reflexes is this physician testing?

A. Cross-extensor

B. Flexor

C. Golgi-tendon

D. Muscle stretch

Answer 31

A 4-year-old comes to the pediatrician for her routine check-up. The physician taps the patellar tendon with a small hammer to test the child’s response. Which of the following reflexes is this physician testing?

D.

Muscle stretch

Question 32

You are walking around on a nice sunny day at the beach barefoot. All of a sudden you feel a prick on your right foot. Immediately you jerk and look at your foot but see nothing. However, you still feel the pain on your foot. Which of the following explains this sensation you still feel?

A. Afterdischarge

B. Duration of the signal

C. Fatigue

D. Flexor contraction

Answer 32

You are walking around on a nice sunny day at the beach barefoot. All of a sudden you feel a prick on your right foot. Immediately you jerk and look at your foot but see nothing. However, you still feel the pain on your foot. Which of the following explains this sensation you still feel?

A.

Afterdischarge