Module 3: Nervous System - Olfactory and Gustatory Systems

Question 1

Olfaction (2)

Answer 1

1) One of the chemical senses

2) Olfactory receptors
a) Activated by airborne chemical substances dissolved in fluid from mucous membranes

Question 2

Olfactory nerves (CN 1) (2)

Answer 2

1) Bipolar cells

2) Found in olfactory epithelium

Question 3

Olfaction process (3)

Answer 3

1) Olfactory nerves (CN I)
a) Travels through ethmoid bone at cribriform plate

2) Olfactory bulbs
a) Dendrites terminate here
b) Masses of gray matter
c) Synapse with other neurons in the pathway

3) Olfactory tracts
a) Carry information to the temporal lobes

Question 4

Smell definition and categories

Answer 4

1) Combination of a limited number of primary odors detectable by the brain
a) Flora
b) Ethereal (dry cleaning fluid)
c) Camphorates (mothball)
d) Musky (perfumes)
e) Peppermint
f) Pungent (Vinegar)
g) Putrid (Rotten eggs)

Question 5

Anosmia

Answer 5

Loss of smell
a) Traumatic Brain Injury (any damage to olfaction pathway)
b) Temporary or permanent
c) Gradual or sudden (ex. of gradual would be a tumor)

Question 6

Gustatory System (Taste) (2)

Answer 6

1) Chemical sense

2) Activated by chemical substances dissolved in saliva

Question 7

Tongue (3)

Answer 7

1) Grips food, helps to reposition food in the teeth, forms a bolus of compact food

2) Assists in swallowing

3) Tongue Anatomy
a) Apex (part that can stick out)
b) Root
c) Frenulum (connects underneath)
d) Papillae

Question 8

Tongue Papillae (2)

Answer 8

1) Raised bumps on the tongue

2) Three types
a) Circumvallate (taste buds)
b) Fungiform (taste buds - hot air balloon shape)
c) Filiform (filaments)

Question 9

Taste buds (2)

Answer 9

1) Contain chemical receptors stimulated by chemicals in food

2) Found on the tongue, surface of the mouth, wall of the pharynx

Question 10

Gustatory Cells (2)

Answer 10

1) Gustatory cells
a) Chemoreceptor cells
b) Terminates in a gustatory hair which projects into the saliva

2) Supporting cells
a) Form bulk of the taste bud
b) Separate the taste receptor cells from each other
c) Help maintain gustatory cells

Question 11

Basal cells (2)

Answer 11

1) Stem cells

2) Divide and differentiate into new support cells, then to new gustatory cells

Question 12

Other gustatory receptors in mouth (3)

Answer 12

1) Nociceptors
a) Pain receptors

2) Thermoreceptors
b) Temperature receptors

3) Both temperature and spice also impact how taste is perceived by brain

Question 13

Taste Pathway (Mouth) (2)

Answer 13

1) Food chemicals contact gustatory hairs

2) Generate action potential in dendrites wrapped around gustatory cells

Question 14

Taste Pathway (Nerves and brain) (4)

Answer 14

1) Facial nerve
a) Taste from anterior 2/3 of the tongue

2) Glossopharyngeal nerve
b) Taste from posterior 1/3 of tongue

3) Thalamus

4) Parietal lobe

Question 15

5 Primary Tastes

Answer 15

1) Sweet - sugars and amino acids

2) Salty - metal salts, especially NaCl

3) Sour - acids like acetic acid (in vinegar)

4) Bitter - drugs like aspirin

5) Savory - certain amino acids and found in fish, ripe tomatoes, aged cheeses and soy sauce

Question 16

Ageusia

Answer 16

1) Loss of taste (anything impacting gustatory pathway)
a) TBI
b) Brain tumor

2) Also impacted by loss of smell
a) Nasal congestion