what causes pupils to dialate?

Answer 1

Dilated pupils are likely an indication of shock and/or of ELEVATED PRESSURE IN THE BRAIN brought on by:

Anaphylaxis
Internal Bleeding
Severe Dehydration
Infection
Reye Syndrome
Glaucoma
A Growth in the Brain

Another reason for pupil enlargement is drug use. Dilated pupils are one sign of Speed or Cocaine use. These drugs are stimulants. Central nervous system depressants, such as narcotics have the opposite effect; they lead to constriction of the pupils

Dilated pupils can also occur with a heart attack, if circulation becomes inadequate.

Answer 2

Pupil dilation can be a result of two things:

1. A decrease in the amount of light coming into the eye
2. Focusing on an object that is either moving away, or is already far away.

A decrease in the amount of light causes the brain to respond by dilating the pupils in an effort to try and Increase the amount of light etering the eye and therefore improve vision.

It also dilates as you focus on an object that is far away. More specifically, a neurological reflex causes your pupil to constict (called the pupillary accommodation reflex) in response to an object coming closer to your eye. This changes the angles at which the light is coming into the eye, and allows the eye to focus more clearly on the object.

Of course, certain drugs can also cause the pupils to dilate. Mydriasis is an excessive dilation of the pupil due to disease or drugs. Although the pupil will normally dilate in the dark, it is usually quite constricted in the light. A mydriatic pupil will remain excessively large, even in a bright environment.

Answer 3

Dilation of the pupils is controlled physiologically by a few different paths. The sympathetic nervous system controls pupillary dilation in a balance with cortical inhibition of the parasympathetic pathway.

Answer 4

less light = more dilation. dilated means bigger pupils. a natural response that allows you to see well in near dark. go to a mirror, close one eye for a minute and watch it as you open it, the pupil is dilated, and quickly shrinks to compensate for the increase in light.

adrenaline and many drugs cause a forced dilation, regardless of light intensity.

Answer 5

pupil is dilated due to contraction of radial muscles of iris (adrenaline)&blockadeof the contractionof the circularand cilliary muscles(hyoscine)

Answer 6

iris muscles typically respond to light. Specifically, the retina sends the light intensity to the brain that responds by manipulating the iris muscles.

Answer 7

Light.

Answer 8

to dilate?

Light
Drugs (depressants)
Even emotional thoughts can change them (such as attraction to others)