Lab 11

Question 1

Sclera

Answer 1

The white of the eye

It protects and shapes the eyeball and provides a sturdy anchoring site for the extrinsic eye muscles.

Question 2

Cornea

Answer 2

The transparent layer anterior (in front of) of the sclera.

It allows light to enter the eye, and it helps bend/refract light rays so that they are focussed on the photo receptors in the retina.

Question 3

Aqueous humor

Answer 3

Provides nutrients to the eye, and keeps the eye in a pressurized state.

Note: it is constantly being produced

Question 4

Iris

Answer 4

The circular coloured portion of the eye which lies on top of the lens.

It regulates the amount of light that gets into the retina.

Contains:
Pupil - innermost central opening.
Inner circular muscle - will shrink the pupil in close and bright light.
Outer radial muscle - will expand the pupil in distant and dim light.

Question 5

Lens

Answer 5

Flexible and able to change its shape to focus light rays for close and far vision into the retina.

Question 6

Vitreous humor

Answer 6

Fluid which fills the inside of the eyeball.

It keeps the shape of the eye round, and absorbs shock.

Question 7

Ciliary body

Answer 7

Attached to the back of the iris.

Contains:
Ciliary muscles - controls the shape of the lens.
Ciliary processes - contain capillaries that produce the aqueous humor

Question 8

Choroid

Answer 8

A highly vascularized and pigmented tissue which is continuous with the ciliary body and wraps around the eye.

It will absorb excess light rays to prevent reflection and scattering of light in the eyeball

Question 9

Retina

Answer 9

The innermost layer which lines the inner eyeball.

Contains photo receptors (rods and cones) which convert light into signals that are sent to bipolar cells, and then to ganglion cells where action potentials are generated.

Question 10

Glaucoma

Answer 10

A condition caused by damage to the optic nerve resulting in vision loss

Question 11

Cataract

Answer 11

A clouding of the lens due to changes in the tissue

Question 12

Myopia

Answer 12

Causes individuals to see closer objects clearly, but distant objects are blurry. (Nearsightedness)

• eyeball is too long
• Lens is too curved
• focal point in front of the retina

Requires a concave lens for correction.

Question 13

Hyperopia

Answer 13

Individuals can see distinct objects clearly, but close objects appear blurry. (Farsightedness)

• eyeball is too short
• lens is too flat
• focal point is behind the retina

Requires a convex lens for correction.

Question 14

Astigmatism

Answer 14

When the cornea or lens has irregularities in the surface curvature.

Objects may be in focus in one axis, and blurred in another axis.

Question 15

Optic disc

Answer 15

Area where the retina meets the optic nerve.

This area is also called the “blind spot” because it lacks photoreceptors.

Question 16

Macula lutea

Answer 16

Contains a central portion called the fovea centralis which is the area in the eye that has the greatest visual sharpness.

This area contains only cones

Question 17

What is the difference between rods and cones?

Answer 17

Rods - stimulated by dim light and produce shades of black, white, grey.

Cones - stimulated by bright light and produce colour vision

Question 18

Accommodation

Answer 18

The ability of the eyes to focus on objects that are near or far.

Question 19

What role do the suspensory ligaments and ciliary muscles play in accommodation?

Answer 19

These structures help change the shape of the lens to help focus on objects of varying distances.

Question 20

Near point

Answer 20

The closest distance at which an object appears to be sharp and focus.

Near points can change over time:
(Average near point distance)
20 year olds = 10 cm
40 year olds = 20 cm
60 year olds = 20-80 cm

(This is why many people develop the need for reading classes)

Question 21

Snellen test

Answer 21

Determines the smallest size of printed letters that could be clearly seen by an individual distance of 20 feet.

This thing:
F
C M
R G S
D Y X H

Question 22

What are the 3 main regions of the ear, and what do they do?

Answer 22

External ear - collects sound waves and brings them into the middle ear.

Middle ear - transfers sound vibrations to the oval window.

Internal ear - contains receptors for hearing and equilibrium.

Question 23

Auricle (or pinna)

Answer 23

The visible portion of the external ear which collects and directs sound waves into the ear

Question 24

External auditory canal

Answer 24

Brings the sound waves picked up by the auricle to the tympanic membrane (eardrum)

It contains ceruminous glands to produce earwax which prevents dust/bacteria from damaging the ear.

Question 25

How does the tympanic membrane (eardrum) work?

Answer 25

When soundwave strike the tympanic membrane, it vibrates back-and-forth at the same frequency as the waves.

It vibrates slowly in response to low frequency (low pitched sounds)

And it vibrates rapidly in response to high frequency (high pitched sounds)

Question 26

What are the ossicles which connect the middle ear to the inner ear?

Answer 26

1. Malleus / hammer
2. Incus / anvil
3. Stapes / stirrup

Question 27

Auditory tube

Answer 27

Connects the middle ear to the pharynx

Functions to equalize the pressure between the atmosphere and the middle ear.

Question 28

Cochlear duct

Answer 28

Contains the organ of corti which is the receptor organ for hearing.

It also has special receptors and hairs meant for converting sound waves into nervous impulses which go to the auditory area of the cerebral cortex via the vestibulocochlear nerve

Question 29

Vestibule

Answer 29

Contains 2 chambers:
- utricle
- saccule

This also contains the receptors for maintaining static equilibrium

Question 30

Static equilibrium

Answer 30

Provide information about the position of the head by monitoring gravity and linear acceleration (straight line changes in speed and direction of movements)

Ex. Walking

Question 31

Semicircular ducts

Answer 31

Contain receptors in evolved in maintaining dynamic equilibrium.

Question 32

Dynamic equilibrium

Answer 32

Use receptors that monitor the position of the head in response to rotational movements.

Question 33

Olfactory adaptation

Answer 33

The inability to distinguish a particular odour after a prolonged exposure to it

Question 34

What are the 5 primary tastes present in humans?

Answer 34

• sweet
• sour
• bitter
• salt
• umami