Eyes and Vision Deprtment of Biology, WCU

Introduction 70% of all sensory receptors Large optic tracts 1/6 exposed 5/6 covered

Structure of the eyeball Poles Tunics (covering) Humor (fluid) Segments

Fibrous tunic Dense, avascular CT Sclera (opaque), cornea (transparent) Functions protects, shapes, muscle anchor light entry

Vascular tunic (uvea) 1. Choroid 2. Ciliary body 5/6th of tunic, nutrients 2. Ciliary body smooth muscle suspensory ligaments

Vascular tunic 3. Iris colored portion pupil regulates light level

Sensory tunic (retina) Pigmented cells absorb light Ora serrata

Retina 1. Photoreceptors 2. Bipolar cells 3. Ganglion cells Rods and cones 2. Bipolar cells 3. Ganglion cells

Light pathway Blind spot

Eye structure Posterior segment vitreous humor Functions transmits light holds retina counteract muscle force

Eye structure Anterior segment Anterior and posterior chambers aqueous humor ciliary process, canal of Schlemm Functions support nutrients and oxygen metabolic waste cleans eye

Accessory structures 1. Eyebrows 2. Eyelids (palpebrae) shade from sunlight prevent trickling perspiration 2. Eyelids (palpebrae) palpedral fissure canthi caruncle (sweat glands)

Eyelid movement Orbicularis oculi Levator palpebrae superioris Functions protect eye prevent dessication spread oil, mucus, saline Eyelashes

Glands 1. Tarsal gland 2. Conjunctiva oily secretion, prevents adhesion 2. Conjunctiva mucus, lubricates, prevent desiccation

Glands 3. Lacrimal location saline (nasal cavity) mucus, antibodies lysozyme

Physiology of vision Light travels in waves Color (i.e. red object reflects red light) Light entering eye is refracted Image is inverted and backward

Physiology of vision Focusing (lens shape change)

Physiology of vision Myopia Hyperopia