Von Bartheld: Chemical Senses

Question 1

Olfactory nerves project from the olfactory bulb through the (blank) and are vulnerable to damage

Answer 1

cribriform plate

Question 2

Olfactory receptor cells have (blank) which binds odorants

Answer 2

cilia

Question 3

(blank) percent of all mammalian genes are devoted to odorant receptors

Answer 3

3-5%

Question 4

Explain how odorants end up opening up Na/Ca channels

Answer 4

Odorants bind GPCRs
Activates adenylate cyclase
Release cAMP
Opens Na/Ca channels

Question 5

Different odorants stimulate (blank) receptor cells

Answer 5

different

*there are a zillion combinations of receptor codes that allow us to perceive a zillion distinct odors

Question 6

Layers of the olfactory bulb

Answer 6

G-MEG
glomeruli
external plexiform layer
mitral cell layer
granule cell layer

Question 7

What do the retina and olfactory bulb have in common?

Answer 7

they both have interneurons - that connect receptor cells to other receptor cells, and to target cells

Question 8

Describe the pathway from olfactory epithelium to the olfactory cortex

Answer 8

1. olfactory receptor cells receive stimulus
2. send it up axons, through the cribriform plate to glomeruli
3. in the glomeruli, these filae synapse on dendrites from mitral and tufted cells
4. mitral and tufted cells project to the olfactory cortex

Question 9

Olfactory filae form (blank) in the olfactory bulb
Glomeruli are the sites where filae (blank) on dendrites from mitral and tufted cells
Mitral and tufted cells project to (blank)

Answer 9

glomeruli; synapse; olfactory cortex

Question 10

What is the significance of the uncus?

Answer 10

If it becomes herniated, it will press on CN III

Question 11

What the heck is the uncus?

Answer 11

Part of the parahippocampal gyrus *has its own fissure that separates it.
The part of the olfactory cortex that is on the temporal lobe covers the area of the uncus, which leads into the two significant clinical aspects of the uncus: uncinate fits and uncal herniations

Question 12

Where does processing of pleasant and unpleasant information light up on MRI?

Answer 12

cingulate gyrus

Question 13

What is unique about olfactory sense and its projection to the cortex?

Answer 13

the olfactory bulb projects DIRECTLY to the cortex

Question 14

What happens to olfactory sensitivity with age?

Answer 14

declines

Question 15

Anosmia

Answer 15

loss of smell

Question 16

Hyposmia

Answer 16

reduction of smell

Question 17

What is Kallmann sydrome an example of?

Answer 17

anosmia

*associated with hypogonadism

Question 18

Some causes of reduction of smell

Answer 18

viral, sinus infection, head trauma
decrease with age
alteration in pregnancy
smoking 
malingering
hallucinations

Question 19

What 3 cranial nerves mediate taste?

Answer 19

7, 9, 10

Question 20

Which cranial nerve brings taste from the anterior 2/3 of the tongue?

Answer 20

CN 7

*to chorda tympani to nucleus solitarius

Question 21

Which cranial nerve brings taste from the posterior 1/3 of the tongue?

Answer 21

CN 9

*project to nucleus solitarius

Question 22

What cranial nerve brings taste from the epiglottis and larynx?

Answer 22

CN 10

*project to nucleus solitarius

Question 23

Where does all information about taste go to in the medulla? Where does it travel to in the thalamus?

Answer 23

nucleus solitarius; ventral posterior medial nucleus *then to insula of cortex

Question 24

Info about taste from the anterior 2/3 of tongue (CN7), posterior 1/3 of tongue (CN9) and epiglottis (CN10) all reaches the (blank) of the brainstem, and then travels to the (blank) of the thalamus. From there, it travels to the (blank) of the cortex.

Answer 24

nucleus solitarius; VPM; insula

Question 25

Which taste papillae do CN 9 supply?

Answer 25

circumvallate papillae

Question 26

What taste papillae do CN 7 supply?

Answer 26

fungiform

Question 27

Discus the distribution of different tastes on the tongue

Answer 27

sweet/unami most anterior salty along periphery sour along side further posterior bitter most posterior

Question 28

Each taste bud contains about (blank) taste cells. How often are these sensory cells need to be replaced?

Answer 28

50-150; every 2 weeks *similar to olfactory cells

Question 29

Taste buds have a pore with (blank). They don't have their own (blank), but can synapse with taste receptor cells.

Answer 29

microvilli; axons

Question 30

T/F: Both ionic channels and GPCRs contribute to the transduction of taste signals.

Answer 30

true

Question 31

What neurotransmitters are involved in transduction of taste signals?

Answer 31

ATP | serotonin

Question 32

Ageusia

Answer 32

loss of taste

Question 33

Hypogeusia

Answer 33

reduction of taste

Question 34

Causes for loss or reduction of taste

Answer 34

``` smoking CF Bell's Palsy oropharyngeal tumors chemotherapy *taste receptors need to turnover ```

Question 35

Cacogeusia

Answer 35

extremely unpleasant taste

Question 36

What chemosensitive structures are innervated by the trigeminal nerve?

Answer 36

nose cornea tongue teeth

Question 37

What are the functions of chemosensitive structures?

Answer 37

to alert to harmful stimuli and initiate their removal

Question 38

There are some "solitary" receptor cells that resemble taste receptors but are innervated by the (blank) nerve

Answer 38

trigeminal

Question 39

General rule: three neurons to cortex. Explain.

Answer 39

1. Receptor cell gives input to bipolar or ganglion cell 2. travels to a sensory nucleus 3. to the thalamus CORTEX

Question 40

What is the exception to the general rule "three neurons to cortex"

Answer 40

olfaction; olfactory bulb can project directly to the cortex!

Question 41

From the cochlear nuclei, there are ascending projections to the (blank) prior to the thalamus

Answer 41

superior olivary nucleus | *gives information about sound on the horizontal axis, where the sound is localized in space