Final answer:
The human eye's structure includes the fibrous tunic (sclera and cornea), vascular tunic (choroid, ciliary body, and iris), and neural tunic (retina with fovea). Each layer serves a specific function, from protecting the eye to focusing light and processing visual information.
Step-by-step explanation:
Layers of the Eye and Their Functions
The human eye is a complex organ with several layers, each having distinct functions. The outermost layer is the fibrous tunic, which includes the sclera and cornea. The sclera, often referred to as the "white of the eye," provides structure and protection, while the transparent cornea allows light to enter the eye. The middle layer is the vascular tunic, consisting of the choroid, ciliary body, and iris. The choroid supplies blood to the eye, and the ciliary body adjusts the lens to focus light. The iris controls the size of the pupil, regulating the amount of light entering the eye.
The innermost layer is the neural tunic, or retina, which contains photoreceptor cells responsible for converting light into neural signals. At the center of the retina is the fovea, which is crucial for high-acuity vision as it contains a high density of photoreceptors.