Final answer:
A cranial reflex is one that involves signals originating from within the brain.
The answer is option ⇒a.cranial
Step-by-step explanation:
A cranial reflex is one that involves signals originating from within the brain. It is also known as a cranial nerve reflex.
Here's a clear and concise explanation:
1. Definition of a cranial reflex:
- A reflex is an involuntary response to a stimulus that occurs without conscious thought.
- A cranial reflex specifically refers to a reflex that originates from within the brain.
2. Origin of signals:
- In a cranial reflex, the signals that initiate the reflex arc come from within the brain itself.
- These signals may originate from various regions of the brain, such as the cerebral cortex, brainstem, or cranial nerves.
3. Examples of cranial reflexes:
- The pupillary reflex is a well-known example of a cranial reflex.
- In this reflex, light entering the eye is detected by the retina and signals are transmitted to the brain.
- The brain then processes these signals and sends impulses via cranial nerves to constrict the pupils, protecting the eyes from excessive light.
- Another example is the gag reflex.
- This reflex is elicited when the soft palate and the back of the throat are stimulated.
- Signals from these areas are transmitted to the brain, which then triggers the reflexive response of gagging, protecting the airway from potential harm.
4. Distinction from spinal reflexes:
- Cranial reflexes are different from spinal reflexes, which involve signals originating from the spinal cord.
- Spinal reflexes, such as the knee-jer k reflex, are initiated and coordinated by the spinal cord without involving the brain.
The answer is option ⇒a