Question

4.3 4.3.1 accommodation is the adjustment of the shape of the lens to see objects clearly, whether they are far or near. the table below has an incomplete process of accommodation. with the aid of the diagram (figure 1 and 2), complete the process by filling in the missing parts of the process in table.

no | distant vision (object further than 6 m) | near vision (object closer than 6 m)
---|----------------------------------------|---------------------------------------
1 | ciliary muscles | ciliary muscles
2 | suspensory ligaments | suspensory ligaments
3 | tension on lens | tension on lens
4 | lens is less | lens becomes more
5 | the refractive power of the lens | the refractive power of the lens
6 | light rays are focused on | light rays are focused on

figure 1: distant vision
figure 2: near vision
(diagrams of eye showing ciliary muscles, suspensory ligaments, lens for distant and near vision)

Explanation:

To solve this, we analyze the process of accommodation in the eye for distant and near vision:

1. Distant Vision (object > 6m) & Near Vision (object < 6m)

Row 1: Ciliary muscles

• Distant vision: Ciliary muscles relax (to allow tension on suspensory ligaments).
• Near vision: Ciliary muscles contract (to reduce tension on suspensory ligaments).

Row 2: Suspensory ligaments

• Distant vision: Suspensory ligaments are taut (under tension) (pulled by relaxed ciliary muscles).
• Near vision: Suspensory ligaments relax (lose tension) (as ciliary muscles contract).

Row 3: Tension on lens

• Distant vision: Tension on lens is high (due to taut suspensory ligaments).
• Near vision: Tension on lens is low (due to relaxed suspensory ligaments).

Row 4: Lens shape

• Distant vision: Lens is less convex (flatter) (high tension pulls it flat).
• Near vision: Lens becomes more convex (rounder) (low tension allows it to bulge).

Row 5: Refractive power of lens

• Distant vision: The refractive power of the lens is low (flatter lens bends light less).
• Near vision: The refractive power of the lens increases (more convex lens bends light more).

Row 6: Focus of light rays

• Distant vision: Light rays are focused on the retina (flatter lens bends parallel light from far objects to retina).
• Near vision: Light rays are focused on the retina (more convex lens bends diverging light from near objects to retina).

Filling the Table:

NO	Distant vision (object further than 6 m)	Near vision (object closer than 6 m)
2	Suspensory ligaments are taut	Suspensory ligaments relax
3	Tension on lens is high	Tension on lens is low
4	Lens is less convex (flatter)	Lens becomes more convex (rounder)
5	The refractive power of the lens is low	The refractive power of the lens increases
6	Light rays are focused on the retina	Light rays are focused on the retina

This explains how the eye adjusts (accommodates) to focus on objects at different distances by changing the lens shape, controlled by ciliary muscles and suspensory ligaments.

Answer:

To solve this, we analyze the process of accommodation in the eye for distant and near vision:

1. Distant Vision (object > 6m) & Near Vision (object < 6m)

Row 1: Ciliary muscles

• Distant vision: Ciliary muscles relax (to allow tension on suspensory ligaments).
• Near vision: Ciliary muscles contract (to reduce tension on suspensory ligaments).

Row 2: Suspensory ligaments

• Distant vision: Suspensory ligaments are taut (under tension) (pulled by relaxed ciliary muscles).
• Near vision: Suspensory ligaments relax (lose tension) (as ciliary muscles contract).

Row 3: Tension on lens

• Distant vision: Tension on lens is high (due to taut suspensory ligaments).
• Near vision: Tension on lens is low (due to relaxed suspensory ligaments).

Row 4: Lens shape

• Distant vision: Lens is less convex (flatter) (high tension pulls it flat).
• Near vision: Lens becomes more convex (rounder) (low tension allows it to bulge).

Row 5: Refractive power of lens

• Distant vision: The refractive power of the lens is low (flatter lens bends light less).
• Near vision: The refractive power of the lens increases (more convex lens bends light more).

Row 6: Focus of light rays

• Distant vision: Light rays are focused on the retina (flatter lens bends parallel light from far objects to retina).
• Near vision: Light rays are focused on the retina (more convex lens bends diverging light from near objects to retina).

Filling the Table:

NO	Distant vision (object further than 6 m)	Near vision (object closer than 6 m)
2	Suspensory ligaments are taut	Suspensory ligaments relax
3	Tension on lens is high	Tension on lens is low
4	Lens is less convex (flatter)	Lens becomes more convex (rounder)
5	The refractive power of the lens is low	The refractive power of the lens increases
6	Light rays are focused on the retina	Light rays are focused on the retina

This explains how the eye adjusts (accommodates) to focus on objects at different distances by changing the lens shape, controlled by ciliary muscles and suspensory ligaments.