Unit 4: The special senses

Question 1

Where is the olfaction located?

Answer 1

Located in the olfactory epithelium of the nose.

Question 2

What does the olfactory epithelium occupy?

Answer 2

It occupies the superior part of the nasal cavity, covering the inferior surface of the cribriform plate and extending along the superior nasal conchae.

Question 3

Name the three kinds of cells in the olfactory epithelium.

Answer 3

• Olfactory receptor cells
• Supporting cells
• Basal cells

Question 4

Describe olfactory receptor cells.

Answer 4

They are the first order neurons of the olfactory pathways.

Question 5

Describe what each olfactory receptor consists of.

Answer 5

Each olfactory receptor is a bipolar neuron with an exposed, knob shaped dendrite and an axon projecting through the cribriform plate that ends in the olfactory bulb.

Question 6

Whats extending from the olfactory receptor cells?

Answer 6

Extending from the dendrites of an olfactory receptor cells are several nonmotile olfactory cili, which are the sites of olfactory transduction.

Question 7

Describe what olfactory receptors are.

Answer 7

Within the plasma membrane of the olfactory cilia are olfactory receptor proteins that detect inhaled chemicals.

Question 8

Explain what odorants are.

Answer 8

Chemicals that bind to and stimulate the olfactory receptors in the olfactory cilia are called odorants.

Question 9

What lines the lining of the nose?

Answer 9

Supporting cells. They provide physical support, nourishment, and electrical insulation for the olfactory receptor cells and help detoxify chemicals that come in contact with the olfactory epithelium.

Question 10

Explain what basal cells are.

Answer 10

They are stem cells located between the bases of the supporting cells. They continually undergo cell division to produce new olfactory receptor cells.

Question 11

Explain what the olfactory glands are.

Answer 11

Within the connective tissue that supports the olfactory epithelium are olfactory glands or bowmans glands, which produces mucus that is carried to the surface of the epithelium ducts.

Question 12

What is the purpose of the mucus produced by the olfactory glands?

Answer 12

The secretion moistens the surface of the epithelium and dissolves odorants so that the transduction can occur.

Question 13

Explain what olfactory transduction is.

Answer 13

Olfacotry receptors react to odorant molecules when a receptor potential develops and triggers one or more nerve impulses. This process is called olfactory transduction.

Question 14

Explain what it adaptation means with olfaction.

Answer 14

Olfaction has a low threshold. Adaptation (decreasing sensitivity) to odors occurs rapidly.

Question 15

Explain what gustation is.

Answer 15

Gustation or taste, is a chemical sense.

Question 16

What are the five primary taste?

Answer 16

• Salty
• Sour
• Sweet
• Bitter
• Umami

Question 17

Where are the receptors for sensations of taste located?

Answer 17

They are located in the taste buds.

Question 18

Explain what taste buds are.

Answer 18

Each taste buds is an oval body consisting of three kinds of epithelial cells.

Question 19

What are the three kinds of epithelial cells in the taste buds?

Answer 19

• Supporting cells
• Gustatory receptor cells
• Basal cells

Question 20

Explain what papillae are.

Answer 20

Taste buds are found in elevations on the tongue called papillae, which increase the surface area and provide a rough texture to the upper surface of the tongue.

Question 21

What are the three types of papillae?

Answer 21

• Vallate papillae
• Fungiform papillae
• Foliate papillae

Question 22

Explain what the vallate papillae is.

Answer 22

They form an inverted V shaped row at the back of the tongue.

Question 23

Explain what the fungiform papillae is.

Answer 23

They are scattered over the entire surface of the tongue that contain about five taste buds each.

Question 24

Explain what foliate papillae is.

Answer 24

Located in small trenches on the lateral margins of the tongue, but most of their taste buds degenerate in early childhood.

Question 25

What covers the entire surface of the tongue?

Answer 25

The entire surface of the tongue has filiform papillae. They contain tactile receptors but no taste buds.

Question 26

Explain what tastants are.

Answer 26

Chemicals that stimulate gustatory receptor cells are known as tastants.

Question 27

How does the tastant work?

Answer 27

Once tastant is dissolved in saliva, it can make contact with the plasma membranes of the gustatory microvilli, which are the sites of taste transduction.