Lab 7: Info

Generally, an auditory stimulus only takes ________ ms to reach the brain but a visual stimulus takes ________ ms.

-8 to 10 -20 to 40

Parts: When looking at the cross-section of the spinal cord for a myotatic reflex, what is surrounding area of the most centralized (butterfly) part called?

-White matter

What is "simple reaction time?

-a case where there is only one stimulus and one response

Book: What is the effector?

-muscle fiber or gland cells that responds to the efferent impulses (by contracting or secreting)

The myotatic reflex employs ____________ neurons.

-only two

In pain stimulation, the reaction of the stimulated limb is accompanied by the ________ reaction of the opposite limb.

-opposite

Striking the ___________ just below the patella ________ the _______________

-patellar ligament -stretches -quadriceps muscle

Book: What are anulospiral endings?

-primary sensory endings -endings of large axons that wrap around the spindle center -stimulated by rate and degree of stretch

PLQ: Calculate conduction velocity

Conduction velocity= Total length of reflex pathway/ (Average reflex latency- 0.002 sec)

How does Distraction affect an individual's reaction time? (include +, - or +/-)

(+) -Distractions increase reaction time significantly, especially in younger individuals

How does Fatigue affect an individual's reaction time? (include +, - or +/-)

(+) -Reaction time deterioration due to fatigue is more marked when he task is complicated than when it is simple. Mental fatigue, especially sleepiness, has the greatest effect

How does Errors affect an individual's reaction time? (include +, - or +/-)

(+) -When a volunteer makes an error (like pressing the button before the stimulus is presented), subsequent reaction times are slower likely due to the subject being more cautious

How does Age affect an individual's reaction time? (include +, - or +/-)

(+/-) -For both males and females, reaction time shortens from infancy into late 20s -then increases slowly until the 50s and 60s -then lengthens faster as the person gets into his 70s and beyond

How does Gender affect an individual's reaction time? (include +, - or +/-)

(+/-) -Males generally have faster reaction times than females

How does Arousal affect an individual's reaction time? (include +, - or +/-)

(+/-) -Reaction time is fastest with an intermediate level of arousal, and deteriorates when the subject is either too relaxed or too tense

How does Drugs affect an individual's reaction time? (include +, - or +/-)

(+/-) -Stimulants tend to decrease reaction times to a point, but see arousal above. Depressants often increase reaction time

How does Warnings affect an individual's reaction time? (include +, - or +/-)

(-) -Generally, reaction times are faster when the subject has been warned that a stimulus will arrive soon

How does Practice affect an individual's reaction time? (include +, - or +/-)

(-) -Practice at a task decreases reaction time

How does Punishment affect an individual's reaction time? (include +, - or +/-)

(-) -Shocking a subject when he reacts slowly does shorten reaction time

Parts: What is a polysynaptic reflex?

-1) Flexor contracts and extensor relaxes to withdraw foot -2) Extensor contracts and flexor relaxes in contralateral leg to support weight -involves interneurons

Parts: What is a monosynaptic reflex?

-1) muscle spindle stimulated -2) sensory afferent neuron excited -3) integration center stimulated -4) alpha motor neuron (effector) stimulates extensor muscle to contract

Parts: What is the path of the pupillary/direct light reflex?

-1) the light source stimulates the right eye's sensory neuron -2) the stimulation travels through the optic nerve and across the optic chiasma to the left superior colliculus of the midbrain -3) the signal travels to both left and right Edinger-Westphal nuclei of the midbrain -4) the signal travels out of the midbrain through the oculomotor nerve to the Ciliary ganglion -5) the signal then travels from the ciliary ganglion through the short ciliary nerve back to the eye

What are the mean simple reaction times for college-age individuals?

-190 ms for light stimuli -150 ms for sound stimuli -155 ms for touch stimuli

Fatigue is correlated with the depletion of ___________, ____________, and _________ in muscle fibers but is also due to _________________ in the muscle by the brain

-ATP -nutrients -oxygen -perception of conditions

What are the factors that may affect an individual's reaction time?

-Age -Arousal -Distraction -Gender -Practice -Errors -Fatigue -Punishment -Drugs -Warnings

Parts: When looking at the cross-section of the spinal cord for a myotatic reflex, what is the most centralized (butterfly) part called?

-Grey matter

PLQ: Why does the response differ for both latency and magnitude when increasing the strength of the hammer tap?

-Latency and magnitude and inversely proportional as strength increases

Is the brain necessary or required for simple reflex functions?

-No

Book: What is a spinal reflex?

-Somatic reflex that is mediated by the spinal cord

Parts: How many steps are there in a myotatic withdrawal reflex and what are they?

-Theres 8 steps -1) muscle stretch receptor gets stimulated -2) muscle spindle gets stimulated -3) stimulation travels up the sensory neuron -4) creates a positive charge at the ends of the sensory neuron -5) travels down motor neuron to cause initial muscle to contract -6) creates a positive charge at the other end of the sensory neuron -7) creates negative charge at the other end of the motor neuron -8) antagonistic muscle stretches

Parts: What goes from the spinal cord to the muscle fiber called?

-motor neuron

What are some examples of a reflex?

-a loud sound or something flying at your eye makes you blink, while a tap on the tendon under the kneecap produces the knee-jerk (or myotatic reflex)

PLQ: What physiological event is responsible for the difference in latency values for reflex and response?

-a response requires more brain function than a low-level neuronal circuitry

If a motor response is initiated, it usually involves a series of ___________ that produce a muscle contraction and a movement of one or more body parts. ___________ are examples of this simple type of stimulus-response reaction

-action potentials -Reflexes

Book: What is a-y coactivation?

-both extrafusal and intrafusal muscle fibers contract -tension is maintained in the muscle spindle and can still signal changes in length

More complex reflexes involve additional _____________, _____________, and more than one ______________. This results in __________ between stimulus reception and the more complex response.

-cells -interneurons -population of motor neurons -a longer delay

Book: What is an abdominal reflex?

-check the integrity of the spinal cord and ventral rami from T8 to T12 -umbilicus moves toward the stimulated site

Voluntary reaction to a cue are considerably more __________ than reflexes: they require _____ brain functions, rather than relying on __________ neuronal circuitry.

-complicated -higher -low-level

Book: What does the motor neuron do?

-conducts efferent impulses from the integration center to an effector organ

The sensory axon synapses __________ with a motor neuron that conducts the impulse of the quads, triggering contraction.

-directly

When muscles are contracted for prolonged periods of time, they ___________

-fatigue

Book: What is the Babinski's sign?

-if something is damaged big toe will dorsiflexion and other toes will fan out

Pupillary constriction is called _________________ while pupillary dilatation is called _______________.

-miosis -mydriasis

Book: All stretch reflexes are _________________ and __________________. They cause muscle contraction in response to increased _____________

-monosynaptic -ipsilateral -muscle length (stretch)

The _____________ or ________________ reflex involves __________ neurons that connect the retina to the midbrain and then convey info back to the _________________

-pupillary -direct light -four -ciliary muscle

What is miosis?

-pupillary constriction

What is mydriasis?

-pupillary dilatation

When light is focused upon the eye, the _____________________ muscle in the iris constricts reducing the aperture (diameter) of the pupil

-pupillary sphincter

Book: What are flower spray endings?

-secondary sensory endings -formed by smaller axons that supply the spindle ends -stimulated by degree of stretch

Striking the patellar ligament stretches the quadriceps muscle. This stimulates __________ receptors in the muscle that trigger an impulse in a _____________ whose cell body lies in the ________ in the __________ region of the spinal cord

-sensory -sensory axon (neuron) -dorsal root ganglion -lumbar

Parts: What goes from the muscle stretch receptors to the spinal cord?

-sensory neuron

_________________ are receptors that detect change and send information to the CNS where it is processed, and _________________ that send information to effectors that produce response appropriate to the situation

-sensory neurons -motor neurons

The flexion withdrawal reflex involves _________ synaptic links.

-several

A simple spinal reflex is produced via ______________ synapses between ____________ and __________

-single -sensory axon (sensory neuron) -Motor neuron

The stimulation of pain sensory neurons leads to the ___________ of _______________ muscles and reciprocal _______________ of ___________ muscles

-stimulation -flexor -inhibition -extensor

Book: What are plantar reflexes?

-tests the integrity of the spinal cord from L4 to S2 -indirectly determines if the corticospinal tracts are functioning properly -toes should flex downwards

Parts: What are the circles protruding from the sensory and motor neurons called?

-the cell body of that neuron

An example of a complex reflex is ___________

-the pupillary or "direct light" reflex

PLQ: Which occurs more quickly the latency for the reflex or the latency for the response experiments?

-the reflex latency

Book: What is the integration center?

-the simple synapse between sensory neuron and motor neuron (monosynaptic) or multiple synapses with chains of interneurons (polysynaptic)

In a simple spinal reflex, the essential central circuitry is confined to __________________

-the spinal cord

Parts: What is the difference between direct light reflex and consensual light reflex?

-the stimulated eye experiences the direct light reflex while the other eye experiences the consensual light reflex

What is nociceptive?

-the stimulation of pain sensory neurons

The major delay in reaction time during a voluntary reaction occurs at _______________________.

-the synapses between the different neurons involved

What is the flexion withdrawal reflex? Name an example.

-the withdrawal of a limb from a painful stimulus -pinprick or the heat of a flame

Book: What does the sensory neuron do?

-transmits afferent impulses to the CNS

What is consensual light reflex?

-when the pupillary sphincter of the other eye constricts at the same time as the stimulated eye

PLQ: Indicate whether random errors should be a concern for your push button experiment. Why or why not?

A random error of this experiment is simply the variability of individual human reactions. However this is accounted for so random errors are really no concern.

PLQ: Explain how increasing the strength of the hammer tap will affect both the latency.

Increasing the strength of the hammer tap will decrease the latency. The latency decreases because you're activating a larger amount of motor neurons.

PLQ: Explain how increasing the strength of the hammer tap will affect both the magnitude.

Increasing the strength of the hammer tap will increase the magnitude of the response. The magnitude increases because larger motor neurons are activated.

PLQ: Identify at least 2 possible systematic errors in your push button experiment.

One possible systematic error in the push button experiment could have been that the subject anticipated the push of the button when conducting the initial visual only push button experiment. Another possible systematic error could have been that the person initially pushing the button did not actually push the button exactly when verbalizing the word NOW when conducting the auditory push button experiments. A random error of this experiment is simply the variability of individual human reactions.

PLQ: How did the Jendrassick maneuver affect the magnitude of the quadriceps' stretch reflex?

The Jendrassik maneuver increased the magnitude of the reflex. This would be observable on the EMG because more muscle fibers would be activated and raise the amplitude of the EMG.

PLQ: The conduction velocity equation is modified for two distinct physiological considerations that affect your reflex latency period but that do not affect the conduction velocity. What are they?

There are two things that affect your reflex latency period but not the conduction velocity. One is the synaptic delay between the sensory and motor neurons. This is accounted for by the (0.002) seconds that are subtracted. The other thing is the reflex pathway that requires the action potential to travel from the sensory neuron to the spinal cord and back down the motor neuron. This is accounted for by multiplying the measured length of the reflex pathway times two.

PLQ: Would the changes caused by the Jendrassik maneuver still be observable?

This would be slightly observable on the EMG because more muscle fibers would be activated and raise the amplitude of the EMG.

Book: What is internal stretch?

by activating the y motor neurons that stimulate the distal ends of the intrafusal fibers to contract, thereby stretching the middle of the spindle

Book: What is external stretch?

by applying an external force that lengthens the entire muscle, such as when we carry a heavy weight or when antagonistic muscles contract

Book: What is a flexor/withdrawal reflex?

causes automatic withdrawal of the threatened body part

Book: What are superficial reflexes?

elicited by gentle cutaneous stimulation

Book: What is reciprocal activation?

motor neurons in spinal cord circuits supplying the contracting muscle are inhibited and antagonist muscles are activated

Book: What are tendon reflexes?

muscle relax and lengthen in response to tension

Book: What is a crossed-extensor reflex?

often accompanies the flexor reflex in weight-bearing limbs and is particularly important in maintaining balance (ex: stepping on broken glass and leaning more on uninjured foot)