Dr Gawad Physiology Course (Reflexes) Online Exam
5MCQs (Only one correct answer)
Each MCQ: 1 mark, Total mark: 5 (you will get the results immediately with correction by the web)
Allowed time: 5 minGood Luck
- 1.
Divergence theory of reflexes means
- A.
Extent of the response in a reflex is directly proportional to the intensity of the stimulus
- B.
Summation is important for propagation
- C.
Occlusion is for near afferent neurons
- D.
None of the above
Correct Answer
A. Extent of the response in a reflex is directly proportional to the intensity of the stimulusExplanation
The correct answer is "extent of the response in a reflex is directly proportional to the intensity of the stimulus." Divergence theory of reflexes suggests that the response in a reflex will be greater if the stimulus is more intense. This means that the extent of the response will increase as the intensity of the stimulus increases.Rate this question:
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- 2.
Regarding occlusion, which is true:
- A.
Tension developed by the simultaneous stimulation of 2 near afferents is more than the sum of tensions developed by stimulation of each of the 2 afferents separately
- B.
Due to overlap of the discharge zones of far afferent fibers
- C.
It is due to reverbrating circuits
- D.
None of the above
Correct Answer
D. None of the aboveExplanation
The given answer states that none of the options provided are true regarding occlusion. This means that the statement about tension developed by the simultaneous stimulation of 2 near afferents being more than the sum of tensions developed by stimulation of each afferent separately, and the statements about overlap of discharge zones of far afferent fibers and reverberating circuits are all false.Rate this question:
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- 3.
Regarding subliminal fringe, which is true:
- A.
Due to overlap of the subliminal fringe zones of both efferent fibers
- B.
It is due to reverbrating circuits
- C.
Never occur in somatic reflex action
- D.
The tension developed by the simultaneous stimulation of 2 far afferents is greater than the sum of tensions developed by stimulation of each of the 2 afferents separately
Correct Answer
D. The tension developed by the simultaneous stimulation of 2 far afferents is greater than the sum of tensions developed by stimulation of each of the 2 afferents separatelyExplanation
The correct statement is about the tension developed by the simultaneous stimulation of 2 far afferents being greater than the sum of tensions developed by stimulation of each of the 2 afferents separately. This phenomenon is known as subliminal fringe and occurs due to the overlap of the subliminal fringe zones of both efferent fibers. It is important to note that subliminal fringe does not occur in somatic reflex action and is not due to reverberating circuits.Rate this question:
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- 4.
Reciprocal innervation means that
- A.
Muscles fibers contacts gradualy
- B.
When a certain group of muscles contracts, the antagonistic group relaxes to the same degree
- C.
Extent of the response in a reflex is directly proportional to the intensity of the stimulus
- D.
None of the above
Correct Answer
B. When a certain group of muscles contracts, the antagonistic group relaxes to the same degreeExplanation
Reciprocal innervation refers to the simultaneous relaxation of the antagonistic muscle group when a certain group of muscles contracts. This ensures smooth and coordinated movement by preventing opposing muscle groups from contracting at the same time. For example, when the biceps muscle contracts to flex the elbow, the triceps muscle relaxes to allow for the movement. This reciprocal relationship allows for efficient and controlled muscle actions.Rate this question:
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- 5.
The following may explain recruitment theory of relexes:
- A.
The motor neurones are still activated by impulses arriving through the reverbrating circuits and interneurons
- B.
Presence of inhibitory interneurons
- C.
Different conduction velocities in the afferent fibres
- D.
None of the above
Correct Answer
C. Different conduction velocities in the afferent fibresExplanation
The correct answer suggests that the recruitment theory of reflexes can be explained by the different conduction velocities in the afferent fibers. This means that the speed at which signals travel through the sensory nerves towards the spinal cord can vary. This variation in conduction velocities allows for the activation of motor neurons by impulses arriving through reverberating circuits and interneurons, as well as the presence of inhibitory interneurons. Therefore, the different conduction velocities in the afferent fibers play a crucial role in the recruitment theory of reflexes.Rate this question:
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