BIOL 1082 Lecture Notes - Lecture 28: Phosphodiesterase, Taste Receptor, Signal Transduction
Document Summary
Tasting, smelling, and seeing (reading: concepts: 50. 3-50. 4 in textbook: compare and contrast vertebrate and invertebrate eyes, explaining how vertebrate eyes focus. **eyes of all vertebrates have a single lens** The human eye is surrounded by the conjunctiva, a mucus membrane; the sclera, a connective tissue; and the choroid, a thin, pigmented layer. At the front, the sclera forms the cornea and the choroid forms the iris. By changing the size the iris regulates the amount of light entering the pupil, the hole in the center of the iris. Inside the choroid, the neurons and photoreceptors of the retina form the innermost layer of the eyeball. The optic nerve exits the eye at the optic disk. The lens, a transparent disk of protein, divides the eye into two cavities. In front of the lens lies the aqueous humor, a clear watery substance. Behind the lens lies the jellylike vitereous humor. How vertebrate eyes focus: changing the shape of the lens.
