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B.Pharm Lab. Instruction Manuals

Pharmacology I

APHE Anatomy, Physiology, and Health Education

Pharmaceutical Analysis

Pharmacy study material

Bones and Skeleton System

Bone disease (Gout) (Rheumatoid arthritis) (Osteoarthritis) (Osteoporosis)

Cancer and music therapy

Memory of water

3.5.3 Pharmacology I

Pilocarpine

Lab 4 Effects of Pilocarpine on Rabbit's or Guineapig's Eye (cont'd...)

Pilocarpine binds with M3 receptor, present in eye and causes the contraction of dilatary pupil (circular muscle) of iris as well as the ciliary muscle and the relaxation of sphincter pupil of iris. Further it causes the paralysis of iris and thus causes the deterioration of lighting reflex.

The detail mechanism of control of lighting reflexes and accommodation: Light enters through the pupil, and is focused by the cornea and the lens onto the retina. The shape of the lens can be changed by the cilliary muscles so that the image always comes to a sharp focus at the retina.

The iris reflex

The eye needs to be able to control the amount of light entering it. In dim conditions, more light is allowed to enter so that a clear image can be formed on the retina. In bright conditions less light is allowed to enter so that the retina is not damaged. This adjustment is done by two sets of muscles in the iris: its circular muscles contract to close up the iris, making the pupil smaller - while its radial muscles contract to open up the iris, making the pupil larger. You can see how this reflex action works in the animation.

Accommodation is the ability of the lens to change its shape to focus near and distant objects is called accommodation.

Adjustment of vision

Object

Ciliary Muscle

Suspensory Ligaments

Muscle tension on lens

Lens Shape

Near

Contract

Slackened

Low

Flat

Distant

Relax

Streched

High

Thin

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