1. What are sensory receptors?

Sensory receptors are specialized cells that detect and respond to specific stimuli like light, sound, touch, and chemicals.

2. Why is 70% of all sensory receptors found in the eye?

The eye is responsible for vision, a highly complex and detailed sense, requiring a large number of specialized receptors.

3. What is mechanoreception, nociception, thermoception?

Mechanoreception: Detects mechanical pressure or distortion (touch, vibration).

Nociception: Detects pain from physical or chemical stimuli.

Thermoception: Detects temperature changes.

4. List accessory structures of the eye. What are their functions?

Eyelids: Protect the eye and spread tears.

Eyelashes: Prevent debris from entering the eye.

Conjunctiva: Lubricates and protects the eye.

Lacrimal apparatus: Produces and drains tears.

Extrinsic eye muscles: Control eye movement.

5. Can you identify the differences between pupil, iris, sclera, cornea, conjunctiva (palpebral and bulbar), eyelashes and eyebrows etc?

Pupil: Central opening controlling light entry.

Iris: Colored muscle controlling pupil size.

Sclera: White, protective outer layer.

Cornea: Transparent, light-refracting front surface.

Conjunctiva: Thin membrane covering the eye and eyelids.

Eyelashes and eyebrows: Protect from debris and sweat.

6. What is a sty? Explain.

A sty is a red, painful lump on the eyelid caused by an infected oil gland.

7. What makes cornea a transparent tissue?

Its organized collagen fibers and lack of blood vessels.

8. Why do we blink? What does it accomplish? What lubricates the movement of eyelids? Where is the lubricant produced?

Blinking spreads tears to moisten and clear the eye. Tears from the lacrimal gland lubricate eyelid movement.

9. What is lacrimal gland? What happens to tears after it is produced?

The lacrimal gland produces tears, which drain through the lacrimal ducts into the nasal cavity.

10. Why do we wipe our nose when we cry? What is the connection? Which structures are involved?

Tears drain into the nasal cavity via the nasolacrimal duct, causing a runny nose.

11. Which are the intrinsic muscles of the eye? List them and explain their function?

Ciliary muscle: Adjusts lens shape.

Iris sphincter and dilator: Control pupil size.

12. Which are the extrinsic muscles of the eye? List them and explain their function?

Superior, inferior, lateral, and medial rectus: Control eye direction.

Superior and inferior oblique: Rotate the eye.

13. What can happen if each of the extrinsic muscle gets paralyzed?

Eye misalignment, double vision, or restricted movement.

14. What are the three layers of the eyeball? What are modifications associated with each of them?

Fibrous (sclera, cornea), Vascular (choroid, ciliary body, iris), Neural (retina).

15. Compartments and segments of the eye. What are the boundaries? Why are they important?

Anterior chamber (cornea to iris), Posterior chamber (iris to lens), Vitreous chamber (lens to retina). They maintain pressure and shape.

16. What makes corneal transplant the most successful transplant?

It lacks blood vessels, reducing immune rejection.

17. What is the role of ciliary body, how is it associated with choroid or vascular body?

Produces aqueous humor and adjusts lens shape; it's part of the vascular layer.

18. What is the association between ciliary body and ciliary zonullae?

The ciliary zonule (suspensory ligament) connects the ciliary body to the lens, controlling focus.

19. How is color of the eye associated with iris?

Iris pigmentation determines eye color.

20. How does sympathetic and parasympathetic activity affect pupil size?

Sympathetic dilates pupils, parasympathetic constricts them.

21. What are parts of retina?

a. Pigmented layer: Absorbs light and prevents scattering. b. Neural layer: Contains photoreceptors and nerve cells for vision.

22. What type of cells are found in the neural layer? List them. What is their role in vision?

Photoreceptors (rods and cones), bipolar cells, ganglion cells. They detect light and transmit signals to the brain.

23. Why is the optic disc called the blind spot?

It has no photoreceptors, so it cannot detect light.

24. Why is vision associated with cones high acuity and colorful?

Cones provide sharp, color vision in bright light.

25. What is macular degeneration? How is it caused?

Loss of central vision due to aging or genetic factors.

26. What is glaucoma? How is it caused?

Increased intraocular pressure damaging the optic nerve.

27. What is special about macula and fovea centralis? Explain.

They provide the sharpest, most detailed vision.

28. What is a cataract? How is it caused?

Clouding of the lens due to aging or injury.

29. Where all in the eye is the light refracted? Which of these is stable and which is changeable? What brings about this change?

Cornea (stable), lens (adjustable via ciliary muscles).

30. What are the changes that need to happen when the eye is focusing on a nearby object? Which muscles are associated with each of them?

Lens thickens, pupils constrict, eyes converge; controlled by ciliary and extraocular muscles.

31. Why does the eye get fatigued when reading for a long time?

Prolonged ciliary muscle contraction causes strain.

32. Differences between myopic, hyperopic and emmetropic eye? How can you correct myopic and hyperopic eye?

Myopic (nearsighted, concave lens), Hyperopic (farsighted, convex lens), Emmetropic (normal vision).

33. What is astigmatism? How can it be corrected?

Uneven cornea curvature; corrected by cylindrical lenses.

34. What is retinal? Where is it present? What is its role in vision?

Light-sensitive molecule in photoreceptors essential for vision.

35. Why do we have only three types of cones (red, green and blue), why not other colors?

These cones detect primary light wavelengths, and the brain combines them for other colors.

36. Where is rhodopsin present? How does it mediate changes inside a rod? When light falls what happens to rods?

In rods, rhodopsin absorbs light and triggers nerve signals.

37. What happens to bipolar cells when rods are hyperpolarized?

They become depolarized and signal the brain.

38. Where is action potential generated? Rods, bipolar cells or ganglion cells? Why is this important?

Ganglion cells generate action potentials, transmitting visual data to the brain.