Part 1: When I see a boat, there is a process in which the light of the image reaches my eye.First, light first passes through the surface of the eye, covered with a clear membrane called the cornea to focus the light into the eye. The next structure is the pupil. Then, the light reaches a clear, watery fluid, called the aqueous humor, which nourishes cornea and lens by supplying nutrition such as amino acid and glucose. The light enters the eye through a hole called the pupil; a round muscle called the iris (colored part of the eye). The iris changes the size of the pupil to light into the eye that helps focus on the boat. Behind the iris is the lens, a clear structure suspended by muscles. The variation in thickness allows the lens to project a sharp image on the retina. Once past the lens, light passes through a fluid called the vitreous humor which nourishes the eye and gives it shape. The final stop for light within the eye is the retina which sends signals to the brain. Part 2: The sound of the race car’s engine travels through the air to my auditory cortex. The sound from the race car’s engine first travels through the outer ear, or the pinna, which is the concentrates outside sound into the structure of the ear. When sound waves from the race car hit the eardrum, they cause tiny bones in the middle ear to vibrate: the hammer, anvil, and stirrup. The vibration of these three bones makes the waves from the eardrum have different volumes of sound.A membrane called the oval window, and its vibrations set off reactions within the inner ear or the cochlea. When the oval window vibrates, it causes the fluid in the cochlea to vibrate. The sound travels to the basilar membrane, the resting place of the Corti. The Corti contains the receptor cells for the sense of hearing. The receptor cells on the Corti are hair cells. The pushing of the hair cells causes them to send a neural message through the auditory nerve into the thalamus, where auditory cortex will interpret the sounds as loud or soft.