For each of the reflex systems A–E, select the most appropriate option for the anatomical location of the reflex centres from the following list.
1. Spinal cord.
2. Hypothalamus.
3. Cerebral cortex.
4. Cerebellum.
5. Brainstem.
6. Cervical spinal segments.
7. Thoracic spinal segments.
8. Lumbar spinal segments.
9. Sacral spinal segments.
- Reflexes coordinating the activities of some pelvic organs.
- Reflexes coordinating vascular tone in the skin, sweating and general skeletal muscle tone to maintain normal core temperature.
- Reflexes coordinating the increases in peripheral vascular resistance that occur on changing from the lying down to the standing up position.
- Reflexes coordinating the acts of swallowing and vomiting.
- Reflexes coordinating the biceps and quadriceps jerks.
Medicine
A. Option 9 Sacral spinal segments. This region is like a minor accessory brain in coordinating micturition and defaecation and contributing to sexual reflexes.
B. Option 2 Hypothalamus. This is the region where responses to both hot and cold environments are coordinated. A hot environment favours vasodilation and sweating; a cold environment favours vasoconstriction and increased skeletal muscle tone.
C. Option 5 Brainstem. This is the region where the arterial baroreceptor reflexes are coordinated.
D. Option 5 Brainstem. This is also the site for the swallowing and vomiting reflexes.
E. Option 1 Spinal cord. The tendon reflexes in the limbs, such as the biceps and quadriceps jerks in response to striking their tendons, are spinal reflexes; they are not confined to any one region of the cord.
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