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comp animal phys > Lab Exam > Flashcards

Lab Exam Flashcards

1
Q

List the physiological steps in a Achilles stretch reflex reaction

A
  1. Tap from hammer on Achilles tendon
  2. Stretching of muscle stimulates muscle spindles
  3. Muscle spindle is associated with afferent sensory neuron
  4. 1a sensory neuron sends generates AP and sends the signal through the dorsal horn into the grey matter
  5. 1a sensory neuron synapses with an efferent a-motor neuron within grey matter and signal travels out along axon through the ventral root.
  6. a-motor neuron stimulates muscle cells in the muscle by releasing ACh.
  7. ACh binds to ligand-gated channels which cause Na+ channels to open.
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2
Q

What is happening during the “reflex time” interval and the “total reaction time” interval?

A

Reflex time: Everything that is electrical in the reaction (from muscle spindle sensing stretch to AP moving down axon of a-motor neuron)
Total reaction time: Electrical + chemical steps of reaction. Chemical = release of ACh and influx of Na+

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3
Q

What is the role of stretch receptors in normal human activity?

A

stretch receptors = proprioceptors

  • They provide feedback to the brain on the position of one’s body parts, especially limbs, independent of visual input.
  • Keep you upright (balance and posture)

-provide input to the brain on the degree to which muscles are contracted, the amount of tension on tendons, and the positions of joints. Proprioceptors also allow weight discrimination.

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4
Q

Why are reflexes in general important physiological mechanisms in the body?

A
  • reflexes protect the organism from harm

- conscious actions take much longer than reflexes. Since reflexes are quick, they are protective.

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5
Q

What is Jendrassik’s maneuver?

A

Interlocking fingers and pulling outward in an isometric contraction. Could make the reflex response LARGER, since maneuver prevents subject from consciously inhibiting or influencing his or her response to the hammer.

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6
Q

How many synapses in Achilles stretch reflex?

A

one (monosynaptic)

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7
Q

Out of the three following cues, which produces a quicker response?

  • auditory
  • visual
  • tactile
A

Tactile > auditory > visual

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8
Q

Why might the site where a subject is touched cause the reaction time to differ?

A

Greater distance of touch site from CNS = greater travel time of signal = greater reaction time.

Could also depend on myelination and axon diameter in the particular site.

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9
Q

Radial smooth muscle in the eye is under control of the _______ ______ _____, which causes pupil to _____

A

Radial smooth muscle in the eye is under control of the SYMPATHETIC NERVOUS SYSTEM, which causes pupil to DILATE.

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10
Q

Circular smooth muscle of the eye is under control of the ____ _______ _____, causing the pupil to _____

A

Circular smooth muscle of the eye is under control of the PARASYMPATHETIC NERVOUS SYSTEM, causing the pupil to constrict.

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11
Q

List several factors that may affect the reaction time of an individual

A

Muscle fatigue, input from the CNS (IPSPs and EPSPs), anticipation, drugs, alcohol, caffeine, depressants, being tired, etc.

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12
Q

Would your reaction time have been faster if instead a twenty dollar bill was dropped between your fingers?

A

Motivation can make reaction time faster

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13
Q

Compare visual reaction times for voluntary plantar flexion and for catching the reaction time ruler. Suggest a reason why they may vary.

A

The length of pathways vary and may change reaction time. The leg (for plantar flexion) is further from CNS than the arm (for catching the ruler).

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14
Q

What do hair cells of the inner ear do?

A

Monitor the orientation of the head relative to the ground and head position during movements.

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15
Q

More than half the sensory receptors of the human body are located in the ______

A

More than half the sensory receptors of the human body are located in the EYES

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16
Q

Light is refracted (bent) by the ___ and ___

A

lens and cornea

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17
Q

greater lens curve means greater __ __ __

A

greater lens curve means greater REFRACTION OF RAYS.

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18
Q

Rods and cones are involved in….

A

conversion of image to a neural message

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19
Q

in the patellar reflex experiment, the weight of the lower leg put tension on the ____ ____

A

quadriceps femoris

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20
Q

Tapping the patellar tendon passively stretches the ____ muscle, activating its ___ ____. The resultant stretch reflex brings about contraction of the ____ muscle, causing knee jerk

A

Tapping the patellar tendon passively stretches the QUADRICEPS muscle, activating its SPINDLE RECEPTORS. The resultant stretch reflex brings about contraction of the EXTENSOR muscle, causing knee jerk

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21
Q

Why are some reflexes MAGNIFIED by DISTRACTION of the subject?

A

Due to release from inhibition by the cerebellum. Allowing subject to watch will inhibit the reflex.

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22
Q

in a normal reflex, the bicep should twitch when the tendon in the antecubital fossa is pressed and tapped with the hammer, indicating the integrity of the ____ ____

A

in a normal reflex, the bicep should twitch when the tendon in the antecubital fossa is pressed and tapped with the hammer, indicating the integrity of the MUSCULOCUTANEOUS NERVE.

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23
Q

in a normal reflex, the tricep muscle should twitch, indicating the integrity of the ____ ____

A

radial nerve

24
Q

What effect would destruction of the ventral horn cells, as in poliomyelitis, have on the patellar reflex?

A

The ability to respond to stimulus when stretched is destroyed.

25
Q

Does the magnitude of the reflex vary directly or indirectly as the degree of background tonus when the block of styrofoam is used?

A
  • Depends on the individual
  • Degree of tension in muscle is related to reflex magnitude. Reflexes should be EXAGGERATED in an excitable state.
  • Reflexes should be LESSENED in a relaxed state.
  • Magnified reflex response in hysteria.
26
Q

Following hard work (physical or mental), what happens to the threshold for knee jerk?

A

It is increased, therefore harder to reach threshold.

27
Q

What is “after discharge?”

A

-when residual NTs are still hanging around after tensing muscles, causing the arms to slowly rise without conscious movement.

28
Q

____ ____ is associated with the downward movement of the toes and a withdrawal of the foot by bending the knee following the stroking of the sole of the foot.

A

PLANTAR FLEXION is associated with the downward movement of the toes and a withdrawal of the foot by bending the knee following the stroking of the sole of the foot.

29
Q

Is swallowing under conscious control?

A
  • Both conscious and unconscious.
  • Person is able to consciously move the bolus of food to the back of the mouth into the PHARYNX using the tongue.
  • The pressure of the bolus in the pharynx stimulates PHARYNGEAL PRESSURE RECEPTORS, which send afferent impulses to the swallowing center located in the MEDULLA. This center activates the muscles that are involved in swallowing (all-or-none).
30
Q

Where are the receptors that initiate the swallowing reflex located?

A

pharyngeal pressure receptors are located in the pharynx

31
Q

Static equilibrium is detected within the ___ and ____ of the inner ear

A

Static equilibrium is detected within the UTRICLE and SACCULE of the inner ear

32
Q

What is the Romberg test?

A

subject closes eyes and the degree of swaying is observed.

33
Q

How does a blind person compensate for the absence of visual input?

A

Blind people rely more upon proprioceptor input as well as sound perception. They are more keen to sound vibrations and air movement to cue in on environment.

34
Q

How could the sway of a person in a Romberg test be quantified?

A

by placing a grid behind them and measuring degree of sway.

35
Q

What 4 important factors allow for the ability to discriminate between hand-held weights of unequal value?

A
  • touch receptors in the skin
  • pressure receptors in the skin
  • proprioceptors in the joints
  • muscle spindles that respond to movement and stretch
36
Q

Why does movement of the hand make weight discrimination more accurate?

A
  • movement of the hand involves more proprioceptors and joints (elbow and shoulder)
  • receiving more info moving up and down with respect to gravity
37
Q

How to calculate DIFFERENCE THRESHOLD

A

final weight - reference = difference threshold

38
Q

What is the benefit of the ability to become habituated to touch and pressure stimuli?
What is the benefit of habituation to touch?

A
  • ex: ability to wear clothes without being conscious of them all day.
  • AVOID SENSORY OVERLOAD
  • When something is constant, it gets “shut out” so that when something different comes along, you can become aware of it and prepare/protect/avoid if it is dangerous.
39
Q

What events must occur when viewing a close object prior to the actual image formation?

A
  • lens must get rounder for close vision (accommodation)
  • pupil gets smaller
  • eyes converge
  • all of these occur to target FOVEA CENTRALIS.
40
Q

What proportion of the nerve fibers were excited to produce a maximal CAP response?

A

100%

41
Q

What factors influence the speed of nerve impulse conduction in vivo?

A
  • myelination and axonal diameter.
  • temperature (not so much in vivo). Heating up without denaturing proteins speeds up conduction. Ions move quicker and enzymes work better.
42
Q

Why do the CAPs recorded on the proximal and distal end of the nerve differ in height and shape? Why do they differ in distance from the artifact?

A

-Perhaps there are less axons further from the artifact.

43
Q

Orthodromic vs antidromic conduction

A

ORTHO:
signal travel in normal direction.
ie. sensory: up the cord, motor: down the cord.

ANTI:
counter to the normal

44
Q

Differentiate between the terms TOTAL and NERVE TRUNK refractory periods for the sciatic nerve trunk. How could you determine if some of the individual nerves are in their relative refractory period?

A
  • Slow and fast fibers will have different refractory periods due to diff conduction speeds, diameter, myelination, etc
  • The point where you can still see 2 same-sized CAPs is the total refractory period of the nerve trunk.
  • As pulses increase, second CAP disappears. This is the NERVE TRUNK RP. AKA none of the nerves are able to generate another AP.
45
Q

What source of error are you introducing when you replace the nerve on the electrodes?

A

-Repositioning the sample. May be reading less nerves than before repositioning.

46
Q

If action potentials are an “all-or-none” response, why does the contraction strength increase with an increase in stimulus strength? Why is there a maximal response by the muscle?

A
  • Because it is a GRADED POTENTIAL of the MOTOR UNIT (motor neurons + all the muscle cell it innervates)
  • As you increase stimulus voltage, you RECRUIT MORE MOTOR UNITS and get GREATER FORCE
47
Q

Why is a greater stimulus intensity required to elicit a muscle twitch when you stimulate the muscle directly rather than stimulating via the nerve?

A

Must get around materials wrapping muscle. There is lots of cytoplasm, connective tissue, etc. Very inefficient. Nothing is insulated (directly cell-to-cell). Not as efficient as nerve.
-whereas motor unit innervates directly. V. efficient.

48
Q

Would you expect the latent period to differ for the muscle when stimulated directly, compared to via the nerve?

A

Cutting out nerve travel time, so latent period is shortened. Still have to do some contraction excitation coupling, but practically no latent period.

49
Q

What do you conclude happened to the number of fibers contracting as the voltage was raised from threshold to that required to produce a maximal contraction?

A

Number of fibers increase as you progressively increase voltage

50
Q

What happens to force as you decrease the time between stimuli?

A

Force increases as you decrease time between stimuli

51
Q

Briefly explain why summation and tetanus are possible in skeletal muscle.

A

Because muscle doesn’t relax, therefore force can be sustained.
Frequent stimulation will stretch elastic components to their ultimate degree. All the force being generated can be used to make CROSS-BRIDGES. Amplitude keeps increasing because we are making things more efficient by stretching so much.

52
Q

What mechanism terminates the action of acetylcholine at the motor endplate?

A

ACETYLCHOLINESTARASE . ACh gets degraded into CHOLINE and ACETIC ACID.
ACh can be regenerated, but no longer binds to ligand channels.

53
Q

Would fatigue occur more readily in an isolated nerve-muscle preparation than in vivo?

A

Fatigue would happen more readily in an isolated nerve than in vivo because there is no circulation of nutrients and oxygen to the isolated tissue or to remove waste.
Isolated tissue relies on DIFFUSION to remove waste from cite and for oxygen.

54
Q

What is the benefit of “warming up” your muscles before exercise?

A

Stretching can realign thick and thin filaments.

Warming up = stretching optimally

55
Q

What is accommodation (in eyes)?

A

The ability to adjust lens strength to focus both near and distant sources of light on the retina

comp animal phys (14 decks)

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