Involuntary movements in response to stimuli which usually employ circuits local to the spinal cord or in the cranial nerves, though not exclusively.

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How fast is the patellar reflex?

I have found a lot of content on the patellar reflex, but I cannot find any studies on how fast the reflex is, from onset of stimulus to innervation of muscles. Does anyone know of either a study or ...
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74 views

Which part of the reflex arc takes the longest time?

If the reflex arc is composed of 4 parts: Activation of sensory receptors, Conduction to and from the CNS, Transmission across the neuromuscular junction & Activation of the muscular contractile ...
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200 views

How are reflexes suppressed?

What neurophysiological process keeps reflex arcs in check? For example, the withdrawal reflex causes the hand to jerk back when the fingers touch something painfully hot incidentally. However, that ...
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Do spinal cord reflexes (such as the knee-jerk reflex) continue to function under general anaesthesia?

The knee-jerk reflex (patellar reflex) is an example of a stretch reflex (myotatic reflex). Stretch reflexes are monosynaptic reflexes happening in the spinal cord without involvement of the brain. ...
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55 views

How does tearing work?

I found the question about tear gas very interesting. Shigeta says there that crying helps the cells of the eye to wash themselves clear of the toxic components in the tear gas. Does non-emotional ...
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570 views

Why did humans evolved the scratch reflex?

I've been wondering about this for some time, and I can't come to an answer... Everybody keeps telling me that scratching one's own skin is bad. It damages the epidermis, creates the hazard of ...
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562 views

In males, why it is difficult to control orgasm?

Why it is difficult to control orgasm in male humans? How are orgasms controlled and what is different between males and females? We can control urine for few minutes, but we can't control orgasm for ...
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What is the mechanism of reflex arcs?

When a reflex arc occurs the signal from the receptor passes straight to the motor neuron instead of being passed onto the brain. This is a rather simplistic explanation, I was hoping to make it more ...
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Which reflex arcs work in Heart with extrasystoles?

I am researching what is triggering the extrasystoles - initial idea from this thread about Which ionic channels of Pacemakers can work in very low frequencies in extrasystole? I am interested in the ...
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What is the difference between intracardiac and extracardiac reflexes in cardiac regulation?

The primary parameters of heart pumping are strength of contractility (inotropic positive; Frank-Starling relationship) rate of relaxation (lusitropic positive) heart rate (chronotropic positive) ...
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Could below zero decibel environment cause arrhythmia? [closed]

While this topic has virtually no real life application and has never been examined due to obvious reasons, it is quite intriguing to me. I've read a lot of speculations and claims about the world's ...
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1answer
90 views

Do all animals exhibit comparable reflex velocity?

First, my exposure to biology is high-school. Should the answer to the question be obvious - please take a moment to laugh, and then point me in the right direction. A quick google search (or perhaps ...
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Why do we squint when tasting very sour things?

Sometimes while tasting a very sour thing (like tamarind, lemon etc.) our eyes squint immediately and involuntarily for a second, but a little later becomes normal again. Why, and how, does this ...
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Does body mass have a bearing on reflex speed?

A reflex is an unconscious action in response to some specific stimulus, e.g., blinking an eye, or pulling the hand away from a hot pin I know from school biology, and reading online that withdrawal ...
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271 views

Why is the Patellar reflex not triggered when the tendon is extended slowly?

I have been previously told that the Patellar reflex (knee-jerk-reaction) exists to prevent the hyper-extension of the patellar tendon. Yet if the impact to the tendon is delivered slowly - i.e. by ...
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Why does looking at bright light trigger sneezing in some people?

Why does looking at bright light trigger sneezing in some people? Are there any recent studies that have found a cause for this Photic sneeze reflex? The Wikipedia article only references studies ...