Anatomy and Physiology Lecture: Eye Anatomy and Physiology

Introduction

• Lecturer: Professor Bob Long
• Course: Human Anatomy and Physiology Part 2, Biology 2402, Del Mar College
• Video Context: Third in a series about the anatomy and physiology of the eye.

Recap and Introduction to Eye Fluids

• Previous discussions on the vascular tunic, choroid plexus, pupillary muscles.
• Focus on fluids within the eye:
  • Anterior Cavity: Space between iris and ciliary body; divided into anterior and posterior chambers.
  • Posterior Cavity: Also known as the vitreous cavity; filled with vitreous humor.

Eye Fluids

• Vitreous Humor:
  • Fills the posterior cavity.
  • Gelatinous, mucous-like texture.
  • Provides shape and support to the eye.
• Aqueous Humor:
  • Fills the anterior cavity.
  • More watery, continually recycled.
  • Maintains intraocular pressure, crucial for eye shape and vision.

Intraocular Pressure

• Derived from secretion and reabsorption of aqueous humor.
• Maintained by the choroid plexus in the ciliary muscle.
• Issues like glaucoma arise from increased intraocular pressure.
  • Causes: Chronic high blood pressure, clogged canal of Schlemm.

Flow of Aqueous Humor

1. Secreted at the ciliary muscle.
2. Flows through the posterior chamber of the anterior cavity.
3. Moves through the pupil.
4. Enters the anterior chamber of the anterior cavity.
5. Reabsorbed at the canal of Schlemm.

Refraction and Refractive Media

• Refraction: Change in direction of light as it moves through different media.
• Four Refractive Media:
  1. Cornea
  2. Aqueous Humor
  3. Lens
  4. Vitreous Humor
• Importance in vision: Bending light to focus images on the retina.

Accommodation

• Process of changing lens shape to focus on objects at different distances.
• Near Focus:
  • Ciliary muscle contracts.
  • Suspensory ligaments loosen.
  • Lens becomes rounded.
• Distant Focus:
  • Ciliary muscle relaxes.
  • Suspensory ligaments tighten.
  • Lens flattens.

Key Definitions

• Cataract: Loss of opacity, resulting in cloudiness in lens or cornea.
• Astigmatism: Irregular curvature of the cornea or lens.
• Emmetropia: Normal vision (20/20 vision).
• Myopia (Nearsightedness): Difficulty focusing on distant objects.
• Hyperopia (Farsightedness): Difficulty focusing on close objects.
• Presbyopia: Age-related hyperopia due to loss of lens elasticity.

Visual Acuity

• 20/20 Vision: Normal vision acuity.
• 20/15 Vision: Better than normal vision.
• 20/40 Vision: Worse than normal vision.
• 20/200 Vision: Legally blind even with corrective lenses.

Conclusion

• The importance of understanding eye anatomy and physiology to diagnose and correct vision issues effectively.

Upcoming Topics

• Neuro tunic and further details about the retina and its function.

Note: Ensure to follow along with the provided notes and textbook references for detailed understanding and visualization.