Lif

In bright light

Figure 12.32

Sympathetic motor nerve fiber

Radially arranged smooth muscle fibers of the iris

Circularly arranged smooth muscle fibers of the iris

Pupil

Parasympathetic ganglion ire

In dim light, the radial muscles of the iris are stimulated to contract, and the pupil dilates. In bright light, the circular muscles of the iris are stimulated to contract, and the pupil constricts.

Sclera

Pigmented choroid coat

Retina

-—- _ . * Pigmented •(•1*1 ™ .1—epithelium

Impulses to optic nerve

Figure

Sclera

Pigmented choroid coat

Retina

Impulses to optic nerve

Horizontal cell Bipolar neuron Amacrine cell

Ganglion cell

Nerve fibers

Receptor cells

Horizontal cell Bipolar neuron Amacrine cell fc t f Light waves

Ganglion cell

Nerve fibers

Vitreous humor

10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment