Dr Gawad Physiology Course (Reflexes) Online Exam

1. Reciprocal innervation means that

Muscles fibers contacts gradualy

When a certain group of muscles contracts, the antagonistic group relaxes to the same degree

Extent of the response in a reflex is directly proportional to the intensity of the stimulus

None of the above

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.

Explanation

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.

2. Regarding subliminal fringe, which is true:

Due to overlap of the subliminal fringe zones of both efferent fibers

It is due to reverbrating circuits

Never occur in somatic reflex action

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

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.

Explanation

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.

3. Divergence theory of reflexes means

Extent of the response in a reflex is directly proportional to the intensity of the stimulus

Summation is important for propagation

Occlusion is for near afferent neurons

None of the above

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.

Explanation

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.

4. The following may explain recruitment theory of relexes:

The motor neurones are still activated by impulses arriving through the reverbrating circuits and interneurons

Presence of inhibitory interneurons

Different conduction velocities in the afferent fibres

None of the above

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.

Explanation

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.

5. Regarding occlusion, which is true:

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

Due to overlap of the discharge zones of far afferent fibers

It is due to reverbrating circuits

None of the above

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.

Explanation

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.