eye

Question 1

sense organ

Answer 1

a group of receptor cells that are able to respond to a specific stimulus

Question 2

What keeps the eyes shape?

Answer 2

Fluid.

Question 3

What keeps the eye moist and where is it made?

Answer 3

Fluid on the surface of the eye made in tear glands.

Question 4

What does the fluid contain and what does it do? How? What do the other structures do?

Answer 4

The fluid contains an enzyme called lysozyme which can kill bacteria. Washed over the eyes by the eyelids when you blink. Eyelids, eyebrows and eyelashes prevent dirt from landing on the surface of the eye

Question 5

What is the retina?

Answer 5

a tissue at the back of the eye that contains receptor cells that are sensitive to light.

Question 6

How is the image formed in the brain?

Answer 6

When light falls on a receptor cell in the retina, the cell sends an electrical impulse along the optic nerve to the brain. The brain uses the impulse from each to build up an image.

Question 7

Where is there no receptor cells and what do you call this part?

Answer 7

Blind spot (it is apart of the retina)

Question 8

What do you call the part of the retina that is mostly closely packed with receptor cells? It is also the part where light is focused if you look directly at an object.

Answer 8

Fovea.

Question 9

What are the two kinds of receptor cells?

Answer 9

Rods are sensitive to dim light but do not respond to color. Cones distinguish the different colors of light but only function when its bright.

Question 10

What are the three different kinds of cones?

Answer 10

Ones sensitive to red, green and blue light

Question 11

What does the fovea contain?

Answer 11

Almost entirely cones packed tightly together to form a clear, sharp image. Rods are found further out on the retina and are less tightly packed– less detailed image produced.

Question 12

define iris

Answer 12

the coloured part of the eye; it contains muscles that can alter the size of the pupil

Question 13

define pupil

Answer 13

a circular gap in the middle of the iris, through which light can pass

Question 14

What do you call: an automatic response to a change in light intensity; the receptors are in the retina and the effector is the muscle in the iris?

Answer 14

Iris reflex or pupil reflex

Question 15

Light rays must be refracted so that they focus exactly onto the retina. Done by?

Answer 15

Mostly by the cornea. Lens makes fine adjustments.

Question 16

cornea definition

Answer 16

a transparent layer near the front of the eye, which refracts light rays entering the eye

Question 17

lens definition

Answer 17

a transparent structure in the eye, which changes shape to focus light rays onto the retina

Question 18

How does the brain interpret an image?

Answer 18

The image is formed onderstebo on the retina. The brain interprets this so that you see it the right way up.

Question 19

Light rays from an object far away are

Answer 19

slightly diverging. They do not need much bending.

Question 20

accommodation definition

Answer 20

changing the shape of the lens to focus on objects at different distances from the eye

Question 21

suspensory ligaments

Answer 21

strong, inelastic fibres that hold the lens in position; they pull the lens into a thinner shape when they are under tension.

Question 22

ciliary muscles

Answer 22

a circle of muscle surrounding the lens and joined to it by the suspensory ligaments; when it contracts, it slackens the ligaments so that the lens becomes fatter

Question 23

What is the function of the optic nerve?

Answer 23

carries impulses to the brain

Question 24

What is the function of the lens?

Answer 24

focus light onto the back of the eye

Question 25

What is the function of ciliary muscles?

Answer 25

controls the tension on suspensory ligaments

Question 26

What is the function of the retina?

Answer 26

tissue containing rods and cones to detect light- cones to detect colour

Question 27

What is the function of the fovea?

Answer 27

it is the area of most cones, light is focused here