Intro to Senses and Olfaction

Question 1

What is a receptor?

Answer 1

A receptor is a structure specialized to detect a stimulus.

Question 2

What kinds of structures can be receptors?

Answer 2

Some receptors are simple nerve endings such as for cold or hot, some are cells such as Merkel’s disc, and some are organs, such as the eye.

Question 3

What are the 5 types of receptors?

Answer 3

Chemoreceptor
Mechanoreceptor
Thermoreceptor
Photoreceptor
Nociceptor

Question 4

What is a chemoreceptor?

Answer 4

Responds to chemical stimuli, eg odor and taste

Question 5

What is a thermoreceptor?

Answer 5

Responds to temperature, eg hot or cold

Question 6

What is a mechanoreceptor?

Answer 6

Responds to physical deformation, eg Porcinian corpuscle to pressure, Meissner’s corpuscle, and proprioception

Question 7

What is a photoreceptor?

Answer 7

Responds to light

Question 8

What is a nociceptor?

Answer 8

Responds to pain

Question 9

What is an interoceptor?

Answer 9

Internal receptors, from viscera ex: nausea

Question 10

What in an exteroceptor?

Answer 10

Stimuli external to the body, ex: papercut

Question 11

Senses can be categorized into these two large categories.

Answer 11

General senses

Special senses

Question 12

What are general senses?

Where are these receptors?

Answer 12

Touch, pressure, temperature, pain

These receptors are widely dispersed through the body

Question 13

What are special senses?

Where are these receptors?

Answer 13

Smell, taste, vision, hearing, and equilibrium

These receptors are in specific locations in the head

Question 14

Where does olfaction physically take place?

Answer 14

2 separate nasal cavities with olfactory recesses, in the most superior part (about 1 sq in)

Question 15

What is a cribriform plate?

Answer 15

Part of the ethmoid bone.
Cranial nerves (#1) passes through, 2 or 3 axons per foramina
Holds chemoreceptors: chemical molecules react with the receptor
Is divided by the perpendicular plates of ethmoid and vomer

Question 16

What is olfactory epithelium?

Answer 16

A specific epithelium found only in the olfactory recess, the rest of the epithelium is pseudostratified ciliated epithelium

Question 17

What three cell types compose olfactory epithelium?

Answer 17

Olfactory receptor cells
Support cells
Basal cells

Question 18

How many neurons are olfactory receptor cells? What do these cells look like?

Answer 18

10-20 million bipolar neurons, have a dendritic bulb with olfactory hairs.

Question 19

What cranial nerve do olfactory axons become?

Answer 19

Cranial nerve 1.

Question 20

Olfactory hairs are the site of olfactory ___________.

Answer 20

Transduction

Question 21

How long do olfactory cells last?

Answer 21

30-60 days

Question 22

What are olfactory hairs?

Answer 22

Olfactory hairs are made of receptor site for odorants on immobile hairs

Question 23

What is an olfactory support cell?

Answer 23

Are columnar epithelium cells that are ciliated

Question 24

What is an olfactory basal cell?

Answer 24

A type of stem cells

Divide and turn into the olfactory cells

Question 25

What is Bowman's gland?

Answer 25

Secretes mucin/mucus

Question 26

What is volatility, and why is it important?

Answer 26

In order to smell, the odorant must be volatile. It must be in a gaseous state and then dissolved in mucus to be detected by the chemoreceptor.

Question 27

What is a mitral cell?

Answer 27

An olfacotry "output" cell. A cell that reaches down and synapses with an olfactory bulb.

Question 28

What is a tufted cell?

Answer 28

A type olfactory reception cell that help form glomeruli.

Question 29

What is a glomeruli?

Answer 29

A tangle of olfactory axons that reach up where mitral and tufted cells reach down. Each glomeruli is dedicated to a particular odor.

Question 30

What is a granule cell?

Answer 30

GABA-releasing cells that inhibit the mitral cells.

Question 31

What is the effect of a granule cell?

Answer 31

An effect of this feedback is that odors can change in quality and significance under different conditions.

Question 32

What is olfactory adaptation?

Answer 32

After 2 minutes, we have almost complete insensitivity to odors Due to granule cell

Question 33

Olfactory receptor cells are the ____ neurons that are directly exposed to the external environment

Answer 33

only

Question 34

The mucus from a Bowman's gland does these three tings:

Answer 34

1- Moistens the surface of the olfactory epithelium 2- Mucus catches viruses and bacteria 3- Replaces surface film to prevent the continuous stimulation of olfactory hairs

Question 35

Are there "primary smells"?

Answer 35

No “primary smells” (contra primary colors); each smell is its own distinct smell

Question 36

How many smells can most people distinguish? Supersmellers?

Answer 36

Most people can distinguish 2,000-4,000 odors, supersmellers up to 10,000

Question 37

Some odors stimulate nociceptors of the _______ nerve.

Answer 37

trigeminal

Question 38

What are examples of odors that stimulate nociceptors?

Answer 38

Ammonia (smelling salts), chlorine, menthol

Question 39

What odors stimulate fight or flight?

Answer 39

skunk, cooking gas, smoke

Question 40

What odors can trigger emotional and/or visceral responses?

Answer 40

Perfume, a favorite food, decaying flesh

Question 41

What are the three olfactory areas?

Answer 41

Lateral Intermediate Medial

Question 42

What is the lateral olfactory area?

Answer 42

Responsible for conscious perception of smell

Question 43

What is the intermediate olfactory area?

Answer 43

Modulation of smell

Question 44

What is the medial olfactory area?

Answer 44

Emotional response to smells