ELM15: Sensory systems 2

Question 1

What is the basic structure of the olfactory system in mammals?

Answer 1

1. Neurons have ends that project to glomeruli in olfactory bulb
2. Go to mitral cells
3. Go to olfactory centres

Question 2

What is basic structure of olfactory system in insects|?

Answer 2

1. Olfactory neurons have ends that project to glomeruli in antennal lobe
2. Go to projection neurons
3. Information goes to mushroom body and lateral horn

Question 3

What is the structure of the human olfactory system

Answer 3

Olfactory epithelium at top of nose with olfactory receptor neurons
Neurons have cilia with receptors
Each receptor activated by a different odorant

Question 4

What is the lay out of the olfactory receptor neurons and the glomerulus in humans?

Answer 4

Neurons converge into one glomerulus

Question 5

What type of receptor are human olfactory receptors?

Answer 5

GPCRs

Question 6

What is the process of olfactory receptors becoming activated?

Answer 6

1. Odorant binds
2. Alpha subunit on G protein swaps GDP for GTP
3. Adenylate cyclase activated
4. Breaks down ATP to cAMP
5. cAMP released
6. Cyclic nucleotide gated channels open
7. Influx of calcium and sodium onto olfactory receptor neuron
8. Depolarisation and AP firing

Question 7

What is the combinatorial code of odorants?

Answer 7

Each odorant binds to several receptors and activates many neurons
Each neuron is activated by many odorants

Question 8

What are the 5 basic tastes?

Answer 8

Bitter sweet umami salty sour

Question 9

Where are taste receptors?

Answer 9

On the end of taste buds on the tongue

Question 10

How do taste receptors pass on information?

Answer 10

Are stimulated and release neurotransmitters
Stimulates gustatory nerves

Question 11

What are the three different types of structures containing taste receptors?

Answer 11

Circumvallate
Foliate
Fungiform

Question 12

What are the three different types of taste receptor molecular structure?

Answer 12

GPCRs
TRP
Epithelial Na channel

Question 13

What are pheromones?

Answer 13

Non volatile chemical cues in environment
Stimulate the vomeronasal organ in nasal cavity

Question 14

What is the normal human hearing range?

Answer 14

20-20000 Hz

Question 15

How do we hear lower frequency waves?

Answer 15

Low pitch

Question 16

How do we hear low intensity?

Answer 16

Quieter

Question 17

What makes up the auditory system?

Answer 17

External middle and inner ear

Question 18

What makes up the vestibular system?

Answer 18

Semicircular canals
Otolith organs

Question 19

What is the structure of the cochlea?

Answer 19

Spiral
Fluid filled

Question 20

How does the cochlea help us hear?

Answer 20

1. Fluid in cochlea is activated and transmits motor information
2. Moving fluid moves basilar membrane
3. Basilar membrane moves relative position of hair cells
4. Sound converted into electrical signal

Question 21

How does potassium enter hair cells?

Answer 21

Stereocillium arranged like a staircase connected by tip links
Movement pulls open potassium ion channels

Question 22

What does opening of potassium ion channels do to hair cells (Mechanotransduction)

Answer 22

1. Potassium enters
2. Depolarisation
3. Calcium enters and glutamate released
4. Information transduced into signal
5. Glutamate activates terminals on spiral ganglia neurons

Question 23

How do we know what direction a sound is coming from?

Answer 23

Compare how long it takes for a sound to each each ear

Question 24

What is the function of the vestibular system?

Answer 24

Detect balance and movement

Question 25

What do the utricle and saccule do in the vestibular system?

Answer 25

Detect head acceleration and position

Question 26

What do the semicircular canals do in the vestibular system?

Answer 26

Detect head rotation and balance

Question 27

How is steady pressure detected?

Answer 27

Merkel cells
Ruffini endings

Question 28

How is vibration detected?

Answer 28

Meissners
Pacinian corpuscles