Chapter 17

Question 1

name two layers that comprise the olfactory organs

Answer 1

• olfactory epithelium
• lamina propria

Question 2

what substance is formed from the combination of olfactory gland secretions and water?

Answer 2

mucus

Question 3

which two molecules must bind for olfaction reception to begin?

Answer 3

odorant to a G protein-coupled receptor

Question 4

stimulation of which special sense is the only sensory information that directly reaches the cerebral cortex?

Answer 4

olfactory stimulation, all others relayed in the thalamus

Question 5

what two brain regions are stimulated by olfaction sensory information which can trigger strong emotional responses and memories to certain smells?

Answer 5

• limbic system
• hypothalamus

Question 6

what is central adaptation?

Answer 6

brain reduces sensitivity of smell after prolonged exposure, but remains sensitive to any new smells

Question 7

which cells located in the olfactory epithelium differentiate to form new olfactory receptors?

Answer 7

basal epithelial cells

Question 8

which type of lingual papillae do not have taste buds but provide friction to help move food around the mouth?

Answer 8

filiform papillae

Question 9

which type of lingual papillae has as many as 100 taste buds per papilla?

Answer 9

vallate papillae

Question 10

after gustatory information is directed to the thalamus, where is the information sent to in the brain?

Answer 10

gustatory cortex of insula

Question 11

which cranial nerve has sensory afferents that send signals about food texture and taste-related sensations?

Answer 11

cranial nerve V

Question 12

which other special sense must be properly functioning for a person to be very sensitive to tastes?

Answer 12

smell, olfactory organs

Question 13

name the six tastes that humans have

Answer 13

sweet, salty, sour, bitter, umami, water

Question 14

which taste receptors located in vallate papillae detect savory tastes due to free glutamate in certain foods?

Answer 14

umami receptors

Question 15

what functions are you performing if you are opening and closing your palpebrae?

Answer 15

opening and closing eye: keeping eye lubricated, removing dust and debris, protecting the eye

Question 16

what does the lacrimal caruncle do?

Answer 16

has glands that produce secretions responsible for gritty deposits found after good sleep

Question 17

what is a chalazion?

Answer 17

cyst resulting from infection of tarsal gland that produces a stye, or localized swelling

Question 18

where is the conjuctiva found?

Answer 18

inner surface of eyelid and outer surface of eyeball

Question 19

what is the common name for conjuctivitis? what is the redness caused by?

Answer 19

pinkeye; redness caused by dilation of blood vessels deep to conjuctival epithelium

Question 20

which two molecules are present in lacrimal secretions that help prevent bacterial or other pathogen-related infections?

Answer 20

lysozyme and antibodies

Question 21

why does the nose often run when we cry?

Answer 21

the nasolacrimal duct delivers tears to the nasal cavity, producing a runny nose

Question 22

what substance fills the anterior chamber of the eye?

Answer 22

aqueous humor

Question 23

what substance fills the posterior chamber of the eye?

Answer 23

vitreous humor

Question 24

what eye structure is commonly known as the “whites of the eyes”

Answer 24

sclera

Question 25

which structure is the most sensitive part of the eye? why?

Answer 25

the cornea, it has numerous free nerve endings

Question 26

why can damage to the cornea result in vision loss?

Answer 26

although the photoreceptors are working, the cornea cannot repair itself, hindering the ability for clear images to form

Question 27

why are most corneal transplants not rejected when recieving a cornea from an unrelated person?

Answer 27

there are no blood vessels to carry the white blood cells which would attack the foreign tissues

Question 28

what are the three layers of the eye?

Answer 28

fibrous, vascular, and inner

Question 29

which layer contains photoreceptor cells?

Answer 29

inner

Question 30

how is eye color determined?

Answer 30

the distribution of melanocytes and density of pigmented epithelium

Question 31

which part of the eye contains pupillary muscles for dilation and constriction of the pupil?

Answer 31

the iris

Question 32

how does the pupil contract in different light?

Answer 32

bright light --> constriction dim light --> dilation

Question 33

which layer of the retina functions to prevent light from reflecting through the neural layer?

Answer 33

the pigmented layer absorbs light, preventing it from bouncing back through the neural layer

Question 34

what type of photoreceptors allow humans to see in dimly lit rooms?

Answer 34

rods, as they do not discriminate colors

Question 35

where are rods distributed within the eyes?

Answer 35

125 million rods form band around periphery of retina, density decreases closer to center

Question 36

where are cones distributed within the eyes?

Answer 36

6 million cones located in macula, center of retina in back of eye

Question 37

what eye structure is commonly known as the "blind spot"? why?

Answer 37

the optic disc, a circular region medial to the fovea centralis; light goes unnotices, as there are no photoreceptors in the disc

Question 38

the blind spot is the origin of which nerve?

Answer 38

optic nerve (II)

Question 39

order of light entering eye:

Answer 39

ganglion cells, bipolar cells, rods & cones, pigmented layer

Question 40

what is diabetic retinopathy?

Answer 40

disease of retina caused by blockage of small retinal vessels, followed by excessive growth, invading the retina and causing damage to photoreceptors

Question 41

diabetic retinopathy is the leading cause of ______ in the US

Answer 41

blindness

Question 42

what is a glaucoma and what causes it?

Answer 42

the buildup of aqueous humor that is unable to drain, causing increased intraocular pressure

Question 43

what is a cataract and what causes it?

Answer 43

clouding of vision caused by loss of transparency of lens due to aging, injury, UV radiation, or drugs

Question 44

what is a focal point?

Answer 44

the specific point of light ray intersection on the retina

Question 45

when light rays projected from a vertical object pass through the lens, what is detected on the back of the eye?

Answer 45

the image is upside down and reversed, but the brain compensates and fixes the image

Question 46

what is 20/20 vision?

Answer 46

one can see clearly at 20 feet what should normally be seen at 20 feet

Question 47

what is emmetropia?

Answer 47

normal vision

Question 48

what is myopia?

Answer 48

nearsightedness

Question 49

what is hyperopia?

Answer 49

farsightedness

Question 50

what is presbyopia?

Answer 50

the loss of lens elasticity in older people

Question 51

what visual pigment is found in rods?

Answer 51

rhodopsin

Question 52

what vitamin is needed to produce rhodopsin?

Answer 52

vitamin A

Question 53

what are the three types of cones that humans possess?

Answer 53

red, gree, blue

Question 54

what part of visual pigments in cones differ from the visual pigment in rods?

Answer 54

cones contain the same retinal pigment, but the retinal is attached to different forms of opsin

Question 55

what is "night blindness" and why does it happen?

Answer 55

dim light is unable to activate rods due to a deficiency in vitamin A and the use of the last reserves of it during the daytime

Question 56

what is the general cause of color blindness?

Answer 56

one or more types of cones are nonfunctional

Question 57

where does the visual pathway begin and end?

Answer 57

begins at the photoreceptors and ends at the visual cortex of the cerebral hemispheres

Question 58

what occurs at the optic chiasm?

Answer 58

the two optic nerves cross over

Question 59

in what brain lobe is the visual cortex?

Answer 59

the occipital lobe

Question 60

what type of receptors are hair cells?

Answer 60

mechanoreceptors

Question 61

what is the scientific term for the outer fleshy portion of the ear?

Answer 61

auricle

Question 62

what is the scientific term for the eardrum?

Answer 62

tympanic membrane

Question 63

what is the secretion produced by ceruminous glands called?

Answer 63

cerumen, or earwax

Question 64

what is otitis media?

Answer 64

a middle ear infection due to the entry of microorganisms into the auditory tube

Question 65

what are the scientific and common names for the three auditory ossicles?

Answer 65

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

Question 66

what are the names of the pair of membranous sacs located in the vestibule?

Answer 66

the saccule and utricle

Question 67

what sensations do the receptors in the saccule and utricle detect?

Answer 67

acceleration and position of head

Question 68

what sensations do the receptors in the semicircular canals detect?

Answer 68

rotation of head

Question 69

what are otoliths?

Answer 69

densely packed carbonate crystals in the otolithic membrane

Question 70

movement of otoliths stimulates which cells to send information to the brain regarding body position?

Answer 70

movement of otoliths triggers macular receptors

Question 71

what is another scientific name for the spiral organ?

Answer 71

the organ of Corti (where hair cells of cochlear duct are located)

Question 72

steps in reception of sound energy:

Answer 72

1. sound waves arrive at tympanic membrane 2. auditory ossicles displaced 3. displacement of stapes at oval window produces pressure waves 4. pressure waves distort basilar membrane on their way to the round window 5. vibration of basilar membrane causes vibration of hair cells against tectorial membrane 6. information about region and intensity of sound relayed to CNS over cochlear nerve