Chp 54 (The Chemical Senses: Taste & Smell)

Question 1

Taste receptor cells occur on the tonque in groups of how many?

Answer 1

in groupd of 50-150 and each of these groups forms a taste bud which is grouped together with other taste buds into taste papillae.

Question 2

The taste buds are embedded in the epithelium of the tonque and make contsct with the outside enviroment through a ______ ______.

What is the average life of a taste bud?

Answer 2

Taste Pore

10 Days

Question 3

Taste receptor capillaries have been grouped into 5 general categories called?

Answer 3

Primary Sensations of Taste

Question 4

Neme the 5 primary senstations of taste?

Answer 4

1. Sour
2. Salty
3. Sweet
4. Bitter
5. Umami

Question 5

“Sour Taste” is caused by what ?

and

What is the intensity of this “sour taste” sensation proportional to?

Answer 5

Acids-by the Hydrogen Ion concentration

logarithm of the hydrogen ion concentrations

Meaning:** the more acidic the food the stronger the sour sensations becomes

Question 6

The Salty Taste is elicited by _____ _____. Mainly by the ____ ____ concentration.

Answer 6

• Ionized Salts*
• Sodium Ions*

Question 7

T or F

The Sweet Taste is not caused by any single class of chemicals

Answer 7

True

Question 8

What are some of Chemicals that cause the sweet tase ?

Answer 8

1. Sugars
2. glycols
3. alcohol
4. aldehydes
5. ketones
6. amides esters
7. some AA’s
8. some small proteins
9. sulfonic acids
10. halogenated acids
11. inorganic salts of lead
12. beryllium

Question 9

Most of teh substances that cause a sweet taste are _____ chemicals.

Answer 9

Organic Chemicals

Question 10

The bitter taste (similar to Sweet) is not caused by any single type of chemical agent.

2 Particular classes of substances are especially cause bitter taste sensations are:

Answer 10

1. Long-Chain organic substances that contain nitrogen
2. Alkaloids

Question 11

Umami is a Japanese word meaning “delicious” , which qualitatevly differs form Sour, sweet, salty and bitter…..

“Umami” is the dominant taste of food containing what?

Answer 11

I-Glutamate such as:

meat extracts and aging cheese

Question 12

Define Taste Blindness:

Answer 12

inability to appreciate gustatory stimuli

unable to taste cetain substances such as Thiourea coumpunds

Question 13

The receptor cells for the smell sensation are

called _____ cells, which are actually ______ _____ cells, derived originally from the CNS itself.

Answer 13

Olfactory Cells

Bipolar nerve cells

Question 14

How many olfactory cells are found in the Olfactory Epithelium?

Answer 14

100 Million interspersed among Sustentacular Cells

Question 15

The Sense of Smell known as ______ is carried out by the _______ nerve or CN 1.

Answer 15

Olfaction

Olfactory Nerve

Question 16

The nasal cavity is made up of three regions.

Name the 3 regions:

Answer 16

1. first, is the nasal vestibule which is the area just inside the nostrils.
2. second is the respiratory region, which is just above the nasal vestibule and is separated by three shelf-like bony structures; the superior, middle and inferior nasal conchae.
3. third, is the olfactory region which is at the top of the nasal cavity and is involved in smelling.

Question 17

The Lining in the respiratory region is a layer of ____ ______ that create mucus to moisten the air and trap pathogens.

Answer 17

Epithelial Cells

Question 18

Lining the olfactory region is a layer of special _____ ______ which form the olfactory epithelium.

Answer 18

special epithelial cells

Question 19

The olfactory epithelium consists of olfactory receptor cells which are ______that respond to molecules, called ______.

Answer 19

chemoreceptors

odorants

Question 20

T or F

The olfactory epithelium also contains cuboidal epithelial cells which support those olfactory receptor cells.

Answer 20

False

The olfactory epithelium also contains columnar epithelial cells which support those olfactory receptor cells.

Question 21

Below the olfactory epithelium is a layer of connective tissue called the______ ______.

Answer 21

lamina propria

Question 22

The lamina propria contains olfactory glands also known as _____ _____ which produce nasal mucus that protects the surface of the olfactory epithelium.

Answer 22

Bowman’s glands

Question 23

Below the lamina propria is the roof of the olfactory region which is formed by the ____ _____ of the ethmoid bone.

Answer 23

cribriform plate

Question 24

The olfactory receptor cells are _____ neurons, meaning that they have ____ _____outside the olfactory epithelium.

Answer 24

bipolar neurons

two projections

Question 25

Bipolar neurons have 2 projections outside the olfactory epithelium:

Name them and what are they responsible for?

Answer 25

1. One projection carries their dendrites to the bottom of the epithelium and gives off hair-like structures called the olfactory hairs, or cilia.

These cilia protrude beyond the nasal mucosa so that they can come into contact with odorants trapped by the mucus.

2. The other projection is an axon that joins up with axons of other receptors to form tiny olfactory nerves - collectively called cranial nerve 1.

Question 26

Tiny olfactory nerves pass through small openings of the _____ _____of the ethmoid bone, called the _____ ______, to enter inside the olfactory bulb.

Answer 26

cribriform plate

olfactory foramina

Question 27

The olfactory bulb contains ____ ____ neurons in the olfactory pathway, and it sends information through the _____ _____ to the ______ _____in the temporal lobe.

Answer 27

second order neurons

olfactory tract

olfactory cortex

Question 28

What is found within the membrane of the cilia?

Answer 28

olfactory receptor proteins : called G-protein coupled receptors and the odorants bind to them.

Question 29

What happens after an odorant binds to a receptor?

Answer 29

signal transduction occurs - meaning that it activates a G protein inside the cell called the G-olfactory protein.

Question 30

Signal transduction activates the G-Protein, triggering the G-protein _____ ______ pathway, which ultimately opens up ____ and ____channels - allowing those ions to flow into the cell.

Answer 30

G-protein coupled receptor pathway

calcium and sodium

Question 31

What happens as calcium ions flows into the cell?

Answer 31

- causes Ca++-activated chloride channels to open up.

Note: Since there’s a higher concentration of Cl- ions inside the receptor cell relative to outside the cell, the Cl- ions flow out of the cell.

Question 32

In the G-Protein coupled receptor pathway….The combination of positive ions coming in and negative ions going out causes the receptor cell membrane to _______, or become____ _____. This causes the neuron to _____ and _____ the sensory information up the ______ _____towards the ______ bulb.

Once the signal reaches the olfactory bulb, the ____ ____ that make up the olfactory nerve synapse with second order neurons called ____ ____.

Answer 32

depolarize

less negative

fire and transmit

Olfactory nerver

olfactory bulb

receptor cells

mitral cells

Question 33

• When second order neuron* ______ cells are activated “receptor cells” release neurotransmitters, like _____ which causes _____ of the mitral cells. This signal then travels through the mitral cell axons which form the _____ _____.
• The olfactory tract splits into a lateral and medial tract.

Answer 33

Mitral Cells

glutamate

depolarization

olfactory tract

Question 34

The olfactory tract splits into ____ and _____ track.

Explain Lateral tract:

Answer 34

lateral and medial tract

1. The lateral tract runs to an area deep within the ipsilateral (same side), temporal lobe, called the piriform cortex which is the primary center for olfaction.

From there some fibers can also go to the limbic system, which is composed of the thalamus, hippocampus and amygdala, which are the centers for emotion and memory. And this is why certain odors can trigger emotions or memories from the past, like the smell of the ocean might remind you of family vacations to the beach.

Question 35

The olfactory tract splits into ____ and _____ track.

Explain Medial tract:

Answer 35

Lateral and Medial Tract

medial tract crosses over to the contralateral (opposite side) piriform cortex meaning that smell from one olfactory receptor can reach both sides of the brain.

Note: so, if you have a cold and the right nasal cavity is completely clogged, some signals can still pass to the right side of the brain from the left nasal cavity.

Question 36

When smell molecules enter the nose they get trapped by what?

Answer 36

1. mucus at the roof of the nasal cavity

Question 37

Once smell molecules are trapped in Nasal Cavity and bind to (1)____ _____ ______ receptors found on the cell membrane of specialized sensory neurons, called (2)______ ______.

This triggers a(3) ____ _____, which travels through the axons of the (4)______ _____to reach the olfactory bulb that sits on the (5)_____ _____ of the ethmoid bone.

Answer 37

1. G-protein coupled receptors

2. olfactory receptors

3. nerve signal

4. olfactory receptors

5. cribriform plate

Question 38

Nerve signal travels through the axons of the olfactory receptors to reach the 1)_____ _____ that sits on the cribriform plate of the (2)_____ bone.

From there the signal travels through the(3)____ _____ to reach the piriform cortex in both temporal lobes, which are the (4)____ _____ for olfaction, and the limbic system where smell is associated with (5)______ and (6)______.

Answer 38

1. olfactory bulb
2. ethmoid bone
3. olfactory tract
4. primary centers
5. memory
6. emotions