Year 12s: what will be the first way you research your future options? >>

Reflex Actions - Does it involve the brain? [PLEASE HELP]

Back in GCSE days, we used to say that reflex actions 'don't involve the brain.'

Is it now more correct to say that they don't involve 'the conscious areas of the brain' since reflex actions still pass through the motor neurones in the spinal cord or the brain - 'the unconscious areas of the brain'?

(edited 7 years ago)

Reply 1

Reality Check

I think it depends what you're defining 'brain' as. I don't think we'd usually define reflex arcs as 'involving the brain', as the impulse does not travel up the spinal cord, so it would be correct to say the reflex actions 'don't involve the brain' but do, obviously, involve the CNS (the spinal cord being part of it)

Reply 2

Jpw1097

Original post by nwmyname

The brain is not required for reflexes. That isn't to say that the reflex doesn't involve the brain, however. Suppose you touch a hot object, and you pull your hand away without even thinking about it (withdrawal reflex), you will also feel pain. Therefore, there must be some signal being sent to the brain, so although your brain was not required to pull your hand away, pain signals were still sent to your brain. Another example is the patellar (knee jerk) reflex, you do not think about moving your leg, that is involuntary, however you can still feel it when your leg kicks. Therefore some afferent signal must be being sent to the brain. With autonomic reflexes on the other hand (e.g. pupillary reflex, blood pressure regulation, heart rate), there is no afferent signal that is sent to the brain, therefore these are not consciously perceived.

Most reflexes cannot be inhibited, such as the patellar reflex or the pupillary reflex (pupil constricts when light is shone in either eye), however some reflexes can be inhibited by higher centres of the brain. Take urination for example. Babies do not have control over when they urinate, it is a reflex. However, as we get older and higher centres of our brain develop, we gain the ability to be able to inhibit certain reflexes. In the case of urination, we can inhibit the reflex, allowing us to urinate at an appropriate time.

So yes, you are right that the brain is not required to initiate a reflex, however, they allow us to consciously perceive reflexes so that we know they are happening, and in some cases, higher centres of the brain enable us to inhibit particular reflexes (such as urination or defecation).

Hopefully that helps a bit.