Special Senses

Question 1

What are the three layers of the eye

Answer 1

1. fibrous tunic
2. vascular tunic
3. neural tunic

Question 2

fibrous tunic (outer layer)

Answer 2

Cornea – protection

Sclera (white of eye) – protection; refraction of light

Question 3

vascular tunic (middle layer)

Answer 3

Iris (colored part of eye) – regulates the light entrance

Pupil (hole in iris) – is the light entrance

Question 4

neural tunic (inner layer)

Answer 4

a) Lens – focusing; refraction of light

b) Retina – contains the •photoreceptors (cones for color/day vision; and
•rods for dark/night vision); •contains Optic Disk (blind spot); and
•Fovea Centralis (area of sharpest
image);
•bipolar neurons (receive impulses from photoreceptors & stimulate ganglion cells); and
•ganglion cells (receive impulses from bipolar neurons; axons of ganglion cells leave the retina in a tight bundle of fibers known as the optic nerve)
•exit of Optic Nerve (sends message to Occipital Lobe of Cerebrum)

Question 5

outer ear

Answer 5

• Pinna – picks up sound waves

- External Auditory Canal – directs sound waves to middle ear

Question 6

middle ear

Answer 6

-Tympanic Membrane (Eardrum) – vibrates; sends sound waves to Auditory Ossicles

-Auditory Ossicles – 3 bones; vibrate and amplify sound waves;
Hammer (malleus); Anvil (incus); Stirrup (stapes)

Question 7

what order does the ear vibrate

Answer 7

eardrum, hammer (malleus), anvil (incus), stirrup (stapes)

Question 8

inner ear

Answer 8

Cochlea – hearing

Semi-Circular Canals – balance

Question 9

mechanism of sound transmission

• have to know this order

Answer 9

1. Sound enters External Auditory canal
2. Vibration of eardrum
3. Vibration of Hammer; Anvil; Stirrup
4. Bulging of Oval Window
5. Stimulation of Hair Cells in Cochlea
6. Bulging of Round Window
7. Stimulation of Auditory Nerve
8. Translation of message in Temporal Lobe of Cerebrum