Vision: Anatomy, Physiology, and Sensory Pathways 13

Lecture 13: Vision

Overview

This lecture covers the anatomy and physiology of vision, focusing on the structure and function of the eye, sensory receptors, image formation, common refractive errors, and the neural pathways involved in visual processing.

General versus Special Senses

Definitions and Comparison

Sensory systems are classified as either general or special senses based on their receptors and neural pathways.

• General senses: Include touch, pain, and temperature. Their stimuli are processed by sensory nuclei and transmitted to the thalamus and primary cortex. Receptors are typically endings of sensory neurons.

• Special senses: Include taste, light (vision), sound, head movement (equilibrium), and smell. Most receptors are not neurons but specialized cells that detect specific stimuli.

Key Differences

• General senses: Sensation is carried by axons of both spinal and cranial nerves.

• Special senses: Sensation is carried only by cranial nerves.

Table: Comparison of Sensory Information

Information Carried	Stimulus Detected By	Signal Carried By
Touch, Pain, Temperature	Receptive endings of sensory neurons	Axons of spinal or cranial nerves
Taste, Light, Sound, Head movement	Specialized receptor cells	Axons of cranial nerves
Smell	Receptive endings of olfactory neurons	Axons of cranial nerves

Objectives of Vision Study

Learning Goals

• List the properties of sensory receptors.

• Describe the structure and functions of the eye.

• Describe the histology and gross anatomy of the eye.

• Describe retinal image formation including refraction and accommodation.

• Define emmetropia, myopia, hypermetropia, presbyopia, and astigmatism.

• Compare and contrast the function of rods and cones.

• Describe the physiology of vision and light transduction.

• Describe the pathway from the eye to the brain.

Additional info: The following topics are inferred from the objectives and will be covered in detail in subsequent sections: eye anatomy, image formation, refractive errors, photoreceptor function, and visual pathways.