BLG 10A/B Lecture 15: Chapter 15
21 Apr 2020
School
Department
Course
Professor
Document Summary
Internal chambers and fluids: the lens and ciliary zonule separate eye into two segments, 1. Lens: biconvex, transparent, flexible, and avascular, changes shape to precisely focus light on retina. Retina: pathway of light entering eye: cornea, aqueous humor, lens, vitreous humor, entire neural layer of retina, and finally photoreceptors. Accommodation of the lenses: changing lens shape to increase refraction, near point of vision, closest point on which the eye can focus, presbyopia: loss of accommodation over age 50. Photoreceptors: photoreceptors (rods and cones) are modified neurons - resemble upside-down epithelial cells, consists of cell body, synaptic terminal, and two segments, outer segment: light-receiving region, contains visual pigments (photopigments) that change shape as they absorb light. Rod vs. cone vision: rods are very sensitive to light, best suited for night vision and peripheral vision. Contain a single pigment, vision is perceived in gray tones only. Pathways converge, causing fuzzy, indistinct images: cones react more quickly than rods.
