The Eye- Humans- Coordination And Response

Question 1

What is the conjunctiva?

Answer 1

Lubricates and protects the surface of the eye

Question 2

What is the Scerla?

Answer 2

tough outer layer that protects the eye

Question 3

What is the cornea?

Answer 3

• Refracts ( bends) light to reach the retina
• Transparent outer part of the eye
  -No blood vessels to supply it with oxygen- oxygen diffuses in from the outer surface

Question 4

What is the Iris?

Answer 4

-controls the diameter of the pupil and how much light enters the eye
-coloured part of the eye that does not allow light to go through

Question 5

What is the Lens?

Answer 5

-Focuses light on the retina
-transparent, biconvex disc that attaches to ciliary muscles by the suspensory ligaments

Question 6

What is the retina?

Answer 6

• contains light receptors called rods and cones
• it detect light and convert it into electrical signals where it is sent to the brain by the optic nerve

Question 7

What are Rods?

Answer 7

-light sensitive cells / receptors in the retina that cannot sense colour
-they detect dim light and enable black and white vision

Question 8

What are cones?

Answer 8

-light sensitive receptors/ cells in the retina that detect colour
-they work best in bright light
-found all over retina
-lot’s at Fovea

Question 9

What is the optic nerve?

Answer 9

-carries impulses from the receptors ( in the eye) to the brain

Question 10

What is accommodation?

Answer 10

Eye focuses light on the retina by changing the shape of your lens

Question 11

What is the reflex known as adjusting to bright/dim light?

Answer 11

The iris reflex

Question 12

Process of the iris reflex- adjusting to bright light

Answer 12

1. Light receptors ( cones and rods) in the retina detect bright light.
   
   2. An electrical impulse is sent via the sensory neurone in the optic nerve to the brain.
   3. The brain processes the information and sends an impulse to the iris.
   4. Circular muscles in the iris contract, and radial muscles relax.
   5. The pupil constricts (gets smaller), reducing the amount of light entering the eye.
   • This prevents excessive light from damaging the retina.

Question 13

Process of Iris reflex- adjusting to dim light

Answer 13

1. Light receptors in the retina detect low light levels.
   
   2. An electrical impulse is sent via the sensory neurone in the optic nerve to the brain.
   3. The brain processes the information and sends an impulse to the iris.
   4. Radial muscles in the iris contract, and circular muscles relax.
   5. The pupil dilates (gets bigger), allowing more light to enter the eye.
   -This helps improve vision in dark conditions.

Question 14

What is the iris reflex for adjusting to dim light?

Answer 14

The iris reflex is an automatic response that controls the amount of light entering the eye, helping to improve vision in low-light conditions. It occurs because dim light reduces visibility, triggering a reflex that dilates the pupil, allowing more light to enter.

Question 15

What is the iris reflex for adjusting the bright light?

Answer 15

The iris reflex is an automatic response that controls the amount of light entering the eye, protecting the retina from damage. Occurs because bright light can damage the retina and triggers a reflex that constricts the pupil allowing less light in

Question 16

Process of looking at distant objects

Answer 16

1. Ciliary muscles relax
   
   2. Suspensory ligaments tighten, pulling the lens by stretching
   3. Lens flattens ( thinner) — it has a smaller curvature, refracting light less for distant vision.
   4. Light is focused onto the retina for clear vision.
      - helps eye to accommodate for far vision

Question 17

Process of looking at near objects

Answer 17

1. Ciliary Muscles contracts
   
   2. Suspensory ligaments loosen and relax, allowing the lens to become rounder.
   3. Lens becomes fatter/thicker and more curved, refracting light more to focus on the near object.
   4. Light is converges onto the retina for clear vision.

Question 18

Why might short sighted people be unable to focus on distant objects?

Answer 18

• Eyeball is too long or cornea is too curved.
  • Light is refracted too much, focusing in front of the retina.
  • Image from distant objects appears blurry.
  • Close-up objects are seen clearly because they focus properly on the retina.

Question 19

Why are long sighted people unable to focus on near objects?

Answer 19

• Eyeball is too short or cornea is too flat.
  • Light is refracted too little, focusing behind the retina.
  • Near objects appear blurry.
  • Distant objects are seen clearly because they focus properly on the retina.

Question 21

What is the eye

Answer 21

A type of sense organ

Question 22

What is the blind spot?

Answer 22

Place on retina w no light/photo receptors