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Biology

Questions tagged [reflexes]

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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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Evolution of scratching

Is scratching (aka the scratching reflex) thought to be inherited from a single vertebrate ancestor or is it something that evolved several times e.g. in birds, mammals etc., i.e. is it a case of ...
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What is the mechanism behind the F-Wave?

Can someone explain the actual mechanism behind the F-wave? Is it really different from a H-reflex response or does it just have another name for historical reasons? The H-reflex (Hoffmann's reflex) ...
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Why do some reflex actions involve interneurons, but some don't?

According to what I know, the reflex arc of knee jerk reflex doesn't involve interneuron, but other reflex action (e.g. removing your hand when touching hot things) do involve interneurons. Why is ...
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What is a reflex pathway?

I know that the pathway of nerve impulses during a reflex action is called a reflex arc. However, I want to know whether the term reflex arc can be called either a reflex path or simple reflex?
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Renorenal Reflex

According to this: The kidney contains afferent sensory nerve fibers that are located primarily in the renal pelvic wall where they sense stretch. I think the stretch is due to urine. If I am ...
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Why do eyes close when we sneeze? [duplicate]

It is a behaviour that is very difficult to control. We can't sneeze with eyes open. Is it a reflex of brain to protect the eye from possible injury in sneezing motion or the neural pathway for ...
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Are there neuron mediated reactions faster than reflexes?

I'm interested in how fast the human body can respond to a stimulus. I know the fastest reflex, the blink reflex, operates around 100ms from stimulus to reaction. I also know that the blink reflex ...
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Why are interneurons needed in the spinal cord for polysynaptic reflexes and somatosensory tracts to the brain?

The single explanation I found for the polysynaptic reflex is that the interneuron diverges into more pathways, such as the efferent motor neuron, the inhibitory neuron to the opposite extensor muscle,...
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Can low temperatures induce a withdrawal reflex?

I read in "Essentials of Pathophysiology: Concepts of Altered Health States By Carol Porth" that "The thermal pain receptors are stimulated only by extremes of temperature such as "freezing cold" ...
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How long can an infant human hold his/her breath as part of the “dive reflex”?

Various other questions on the site have talked about the Diving Reflex, which is also known as the Mammalian Diving Reflex. This reflex is observed in mammals of various species, but also in human ...
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Stopping the Gag Reflex: How and why does it work?

I was talking to some friends over the weekend, and one of them made a comment about gagging. He said that he read or watched that clenching your thumb with your other fingers (making a tight fist ...
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1answer
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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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Which part of the reflex arc takes the longest time?

The reflex arc is composed of 5 parts: sensory receptors, afferent neuron(s), synapses within the central integrating station, efferent neuron(s) and the effector (includes transmission across the ...
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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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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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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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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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1answer
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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
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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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1answer
656 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 ...