Anatomy and Physiology Lecture Notes

Introduction

• Instructor: Professor Pablo
• Course: Human Anatomy and Physiology (Series)
• Institution: Del Mar College
• Context: Delivered during the coronavirus shutdown
• Focus: Visual physiology, specifically rods and cones

Photoreceptors

• Definition: Specialized neurons in the retina
• Function: Detect photons of light
• Types:
  • Rods
  • Cones

Eye Anatomy Overview

• Layers of the Eye:
  • Fibrous Tunic: Includes sclera and cornea
  • Vascular Tunic: Includes blood vessels, choroid, ciliary body, iris, pupil
  • Neural Tunic: Includes retina and pigmented epithelium

Pigmented Epithelium

• Function: Absorbs photons not captured by photoreceptors
• Location: Deep to the choroid layer, covering the inside of the eye

Retina

• Function: Contains photoreceptors and layers of neurons
• Photoreceptor Layers:
  • Rods
    • Structure: Elongated cylindrical outer segment with membranous discs
    • Visual Pigment: Rhodopsin
    • Function: Active in low light, black and white vision
  • Cones
    • Structure: Tapered conical outer segment
    • Visual Pigments: Iodopsins (1, 2, 3)
    • Function: Color vision (red, green, blue cones)

Retinal Organization

• Photoreceptor: Faces the pigmented epithelium
• Layers:
  1. Photoreceptors
  2. Bipolar Cells
  3. Ganglion Cells: Axons form the optic nerve

Light Pathway

• Non-visible Photon: Passes through ganglion, bipolar, and photoreceptor, absorbed by pigmented epithelium
• Visible Photon: Absorbed by photoreceptor, stops neurotransmitter release, triggers bipolar and ganglion cells

Pathologies

• Diabetic Retinopathy: Damage due to diabetes, affects retinal neurons, can lead to neovascularization

Additional Concepts

• Fovea Centralis:
  • Location: Center of the macula
  • Function: Focuses most incoming light, high density of cones
• Optic Disc:
  • Function: Exit point for optic nerve, no photoreceptors, creates blind spot

Review Questions

• What is the fovea centralis?: Central spot in the macula with high cone density.
• What is the optic disc?: Spot for optic nerve exit, no photoreceptors, blind spot.

This lecture covered visual physiology, specifically focusing on the structure and function of rods and cones, and how they are organized within the retina. Understanding these basics is crucial for comprehending how our eyes process visual information and adapt to different lighting conditions.