Hearing, Taste and Smell

Question 1

What are the five different chemical senses?

Answer 1

Salty, sour, sweet, bitter and umami (picks up MSG, associated with proteins and meats)

Question 2

What is the turnover rate for taste buds?

Answer 2

10-14 day turnover

-as we get older we see differences in the density of taste buds

Question 3

Where are taste buds located?

Answer 3

Taste buds are located on the side of your papilla. A group of taste cells inside each taste bud. Each taste cell is only able to pick up one taste

Question 4

How is the taste cell activated?

Answer 4

Each taste cell projects microvilli out into the trench. When it comes in contact with a taste, it depolarizes the taste cell and sends the message out of the taste bud via the gustatory afferent axons

Question 5

What cranial nerves are involved with taste?

Answer 5

–Glossopharyngeal (IX)
–Facial nerve (CN VII)
–Vagus nerve (CN X)

Question 6

Describe conditioned taste aversion

Answer 6

Expose an animal to a novel flavor, they eat it and get sick, and they will not eat it again (only takes one trial). Classic conditioning

• Radiation=unconditioned stimulus
• Plastic water bottle=conditioned stimulus
• Lithium chloride

Question 7

What are differences among species related to olfaction?

Answer 7

Other mammals have a larger brain area devoted to their olfactory system, and a higher number of olfactory receptors. Can smell something at a much lower intensity then humans can

Question 8

What three cells make up the olfactory epithelium?

Answer 8

Olfactory receptor cells, supporting cells, basal cells

Question 9

What do olfactory receptor cells do?

Answer 9

Pick up and detect odorant molecules. Involved in transduction. Are a type of neuron

Question 10

What do supporting cells do?

Answer 10

Act like astrocytes. Help olfactory receptor cells. Produce mucus that collects odorants

Question 11

What do basal cells do?

Answer 11

Replace receptor cells once olfactory receptor cells die (1-8 weeks). Transform and take the place of olfactory receptor cells. Neurogenesis is occuring

Question 12

Describe olfactory receptor cells

Answer 12

•Neurons
–Single dendrite with thin cilia
•Odorant receptors
–Umyelinated axon
•Cribriform plate: project axons into cribiform plact and collect up into the olfactory bulb and connect with another group of cells
•Olfactory nerve (Cranial nerve I)
•Regenerate
–1-8 weeks

Question 13

Describe how olfactory receptor cells transduction works

Answer 13

1. Odorant binds to the receptor
2. Na and Ca enter the cell
3. Cl leaves the cell

Question 14

What is a glomeruli?

Answer 14

Collection of olfactory neurons. Nose uses olfactory receptors that it has and combine them to make more complex smells

Question 15

What area of the brain does olfactory info skip along its pathway?

Answer 15

Thalamus

Question 16

What does intranasal drug delivery accomplish?

Answer 16

It bypasses the blood brain barrier. Allows large molecules to be absorbed by the blood vessels in the nose, therefore you get a higher concentration of the drug in the brain

Question 17

What is sound?

Answer 17

Compressed air

Question 18

What structures make up the outer ear?

Answer 18

• Pinna

- Auditory canal

Question 19

What structures make up the middle ear?

Answer 19

• Eardrum

- Ossicles

Question 20

What structures make up the inner ear?

Answer 20

Cochlea

Question 21

What is the pathway that sound travels to reach the inner ear?

Answer 21

Pinna-Auditory Canal- Tympanic membrane- Ossicles- Oval Window- Cochlea

Question 22

What is an ear infection?

Answer 22

Build up of fluid in the middle ear in the Eustachian tube can’t drain fluid like it should so it builds up

Question 23

What is the cochlea made up of?

Answer 23

•Three fluid filled canals
–Endolymph (cochlear duct)
–Perilymph (tympanic and vestibular canals)

Question 24

What part of the basilar membrane detects high frequency sounds?

Answer 24

Base- narrow and tight= harder to move

-connected to the stapes

Question 25

What part of the basilar membrane detects low frequency sounds?

Answer 25

Apex- wide and loose= easier to move

Question 26

What is the Organ of Corti?

Answer 26

Inside of the cochlea

• made up of the basilar membrane and hair cells
• tectorial membrane covers the top

Question 27

What do the hair cells do?

Answer 27

As the basilar membrane is moved (vibrated), the hair cells will move the tectorial membrane. Depending which way they move there is depolarization of hyperpolarization

Question 28

What do inner hair cells do?

Answer 28

send signals that get transmitted into sound

Question 29

What do the outer hair cells do?

Answer 29

tell you the position of the basilar membrane

Question 30

When do stimulation occur in the organ of corti?

Answer 30

When the hair cells are bent towards the longer stereocili. Depolarization

Question 31

When does inhibition occur in the organ of corti?

Answer 31

When it is bent toward the shorter stereocili. Hyperpolarization

Question 32

Where does depolarization and hyperpolarization occur on the sound wave?

Answer 32

Depolarization occurs at the peak of the sound wave and Hyperpolarization occurs at the base of the sound wave. Codes it for the brain so it can distinguish whether the sound is high or low frequency

Question 33

Where in the brain do we first mix information from both ears?

Answer 33

Superior Olivary nucleus- start doing some localization. Inside the pons

Question 34

What is conduction deafness?

Answer 34

Damage to the ear drum, issues with the ossicles, blockage in the auditory canal, etc. Inability of sensory receptors to pass on info to the rest of the ear and brain

Question 35

What is sensorineural deafness?

Answer 35

Damage to hair cells, problems with cranial nerves that are collecting info from the hair cells. When kids are born deaf it tends to be this.

Question 36

What is central deafness?

Answer 36

Very rare, can occur if you have a stroke on both sides of your brain, damage to the auditory brain structures

Question 37

What is tinnitus?

Answer 37

Ringing in the ears

-illusion of sound when there is none