LAB 9– The Special Senses

Question 1

What is it within the eye of a sheep that appears iridescent?

Answer 1

choroid coat

Question 2

What is the special reflecting surface called that appears iridescent within a sheep eyeball?

Answer 2

tapetum lucidum

Question 3

What is the ciliary body?

Answer 3

the black pigmented body that appears on a halo encircling the lens

Question 4

What is the lens?

Answer 4

a biconvex structure that is opaque and hard

Question 5

What is the suspensory ligament?

Answer 5

the halo of delicate fibres attaching the lend to the ciliary body

Question 6

What is the anterior continuation of the ciliary body penetrated by the pupil?

Answer 6

the iris

Question 7

What is the delicate white or yellow membrane overlying the darkly pigmented choroid?

Answer 7

the retina

Question 8

Near response has what 3 processes?

Answer 8

1. Convergence of the eye balls
2. Constriction of the pupil
3. Accommodation of the lens

Question 9

What is the Scellen chart?

Answer 9

chart used by doctors to test vision assessing if you are able to read all eight lines from 20ft away.

Question 10

When is sound heard?

Answer 10

when vibrations in the air strike the eardrum causing it to vibrate.

Question 11

The vibration on the eardrum transmits across the middle ear by what?

Answer 11

the ossicles

Question 12

Movement of the stapes in the ____________ sets up pressure waves in the fluid of the inner ear.

Answer 12

oval window

Question 13

The movement of the fluid displaces the basilar membrane and causes what to happen?

Answer 13

causes stimulation of hair cells in the organ of Corti.

Question 14

When and how does conductive deafness occur?

Answer 14

when the structures that conduct the vibrations to the inner ear are damaged.
may be caused by accumulation of ear wax, ear infection, or rupture of the eardrum due to sudden loud noise or scuba diving

Question 15

When and how does sensorineural deafness occur?

Answer 15

from damage to the hair cells of the inner ear, or other part of the cochlea or auditory nerve.
may be caused by chronic loud noise exposure or a variety of diseases including rubella or measles.

Question 16

What is the most common type of deafness?

Answer 16

sensorineural deafness.

Question 17

What is it called when input from both ears is weighted to determine the relative difference in time between when the sound is received by the ears?

Answer 17

sound localization

Question 18

The cerebellum provides fine control of the postural muscles. To do this, input is required from what?

Answer 18

the vestibular system, proprioceptors, and from visual systems

Question 19

When does increased sensitivity result?

Answer 19

the density of receptors is higher

Question 20

What is the sclera and what does it do?

Answer 20

the white of the eye, covers most of the ear surface.

contains blood vessels and nerves

Question 21

What is the cornea and what does it do?

Answer 21

the anterior transparent region of modified sclera that admits light into eye

Question 22

What is the choroid and what does it do?

Answer 22

Deeply pigmented layer of tissue before retina.

Absorbs stray light

Question 23

What is the ciliary body and what does it do?

Answer 23

thickened extension of choroid and forms a muscular ring around lends
supports iris and lens and secretes fluid called aqueous humor

Question 24

What is the iris and what does it do?

Answer 24

Adjustible diaphragm that controls diameter of pupil

Contains pigmented cells

Question 25

What is the lens and what does it do?

Answer 25

Flattened, compressed, transparent cells make up lenses

changes shape to help focus light

Question 26

What is the retina and what does it do?

Answer 26

A cup shaped outgrowth, part of the brain

A thin transparent membrane attached to the rest of the eye

Question 27

What are the 2 locations where the retina is attached to the eyeball?

Answer 27

at the optic disk and ora serrata

Question 28

Why is it important that the retina stays closely adhered to the choroid?

Answer 28

choroid supplies oxygen and nutrients to retina

Question 29

What is the structure of the fovea centralis?

Answer 29

a tiny pit in the center of the macula.

Question 30

What does the fovea centralis’s function?

Answer 30

produces the most finely detailed images.

Question 31

What is the function of the extrinsic eye muscles?

Answer 31

move the eye cranial nerves oculomotor (III), trochlear (IV), and abducens (VI) supply the extrinsic eye muscle.

Question 32

Why does pupil size change as you focus on words?

Answer 32

pupil size increases because accommodation of the lenses occurs

Question 33

What is the process of accommodation of the lens that is required for near vision?

Answer 33

The process of accommodation of then lens is that the ciliary muscle around lens contracts, narrowing the diameter of ciliary body, relaxes the fibers of suspensory ligament, and lens relaxes into thicker shape.

Question 34

Why is it more tiring reading then looking at trees for a bird?

Answer 34

Ciliary muscle contracts and narrows in diameter, switching the tension from the ligament to the muscle causing our eyes to become tired

Question 35

What cranial nerve brings sensory information from the face into the brain?

Answer 35

trigeminal cranial nerve carries this information

Question 36

What muscle in the face contracts during blinking?

Answer 36

the orbicularis oculi muscle contracts

Question 37

What cranial nerve is involved in blinking?

Answer 37

facial nerve (VII)

Question 38

What part of the brain is involved in sound localization and when does it measure to determine the origin of a sound?

Answer 38

superior olivary nucleus

measures difference in time between then sound arrives at both ears.

Question 39

What types of information is required by the cerebellum to maintain erect posture?

Answer 39

from the proprioceptors, the vestibular system and the visual systems