What do we need to visualize the universe? ________ that respond to light intensity Receptors that respond to __________ Mechanism to _____ light on receptors Control over _______ of light striking receptors __________ of light to receptors ________ of receptors ________ of organs (eyes) Pair of organs for ________ ________ Ability to ______________ organs BIOL 2010 Human Anatomy & Physiology I

What structures help protect the eye? Shade and protect (Palpebrae) protect Protective hairs Protective mucosa

How do we keep our eyes moist? _____________________: Keeps eyes moistened with tears, which are formed in lacrimal gland. Palpebrae help spread tears across eyes Excess tears drain via ________ into _____________, then _________________ and finally into nasal cavity Where do tears go? Milk squirting…

How do we move our eyes? Superior view Lateral view Eye movements accomplished via 6 extrinsic eye muscles: * Which cranial nerves innervate w/c muscles?

What are the layers of the eye and what are their functions? 3 distinct layers of tissue in eye: ____________ Sclera & cornea ____________ Choroid, etc. ____________ Retina Clear light pathway

How do our eyes control the amount of light entering? _________ refracts light as it head towards lens _________ is attached to ciliary body and consists of contractile tissue (smooth muscle). Coloration is due to varying amounts of melanin _____ is simply the hole in the center of the iris

How do we focus the image? _____________ contains smooth muscle fibers, which allow the distortion of the lens via ________________. _____________________ are very vascular and produce ________ _________ (watery fluid in anterior compartment).

How is light converted into action potentials? 3 neuronal layers of the retina: ___________________ Also ____________ and __________________

Are all photoreceptors created equally? _________ (~120 million each) ______ (~6-7 million each)

Light causes ___________ to “bleach” and it must be recharged. The ____________ is moved to the _____________ _____ of the retina (back to ____________) How is light converted into action potentials?

The Senses: Vision Photoreceptors are rather unique in that they are __________________ as a result of stimulation. In dark (no stimulus) leaky Na+ channels. In light (stimulus) Na+ channels close and hyperpolarization occurs How is light converted into action potentials?

How do we see milions of colors with only “3 primary color” receptors? Different colors are identified by analysis of the ____________ of each of the 3 colors (RGB).

Is a rose by any other color still a rose? Heritable mutation of genes coding for red/green on the ________________ result in color blindness (dichromatism) If no cones at all… If red-green color blind…