Sensory systems

Question 1

Which organs are responsible for hearing, smell, vision, gustation, and pain?

Answer 1

the ears, nose, eyes, tongue, and skin

Question 2

Which factor is important to give smell to a compound?

Answer 2

Odorants, small VOC

Shape is crucial for odor

Question 3

The smell receptors use the same activation mechanism as which taste receptors?
a. Sweet, sour and salty
b. Salty, umami and bitter
c. Sweet, bitter and umami
d. Sour, bitter and umami
e. Bitter, sweet and salty
Describe the general activation mechanism of these receptors.

Answer 3

Sweet, bitter and umami G protein coupled.

Question 4

What are photoreceptors?

Answer 4

Rhodopsin located in disks of RODS (night vision)

and photopsin located in disks of CONES (colour vision)

Question 5

Light results in the opening of sodium channels in the membrane of photoreceptor cells, resulting in a depolarization of the rod (or cone). True or false? Describe the activation
mechanism.

Answer 5

FALSE

Retinal undergoes change in conformation when absorbs light, activating opsin.
G protein coupled receptor. Cation channel closes. Creates hyperpolarisation. Relays visual information to synaptic terminal.

1. Light moves to retina
2. Absorption by cones and rods
3. Signal is passing neural cells
4. Signal to optic nerve
5. Processing of the signal in the brain

Question 6

Why is the signal-transduction pathway of hearing faster compared to taste and smell?

Answer 6

An ion channel which is faster than the cascade receptors of G protein coupled receptors that involve second messengers.

Question 7

Describe the signal-transduction pathway of the sensory system when carbohydrates bind on
the taste buds.

Answer 7

Similar for bitter, sweet and umami.

Taste receptor coupled to G protein with alfa subunit gustducin

Question 8

On which 2 stimuli do the capsaicin receptor react?

Answer 8

The capsaicin receptor is an ion channel that reachts both on heat and capsaicin (chemical/spice)

Question 9

What is a sense?

Answer 9

transducer from the physical
world to the brain where we
interpret the information

Question 10

What is olfaction?

Answer 10

Sense of smell

Question 11

The olfactory signal-transduction cascade is what type of receptor?

Answer 11

G Protein Coupled Receptor

Question 12

How many olfactory receptor neurons do humans have? (And dogs?)

Answer 12

Humans have 5 million

Dogs have 220 million

Question 13

What is anosmia?

Answer 13

lack of functioning olfaction = incapability to smell

Can be due to inflammation (temporary) or due to death of olfactory neurons, brain injury or mutations in receptor genes.

Question 14

What are the five primary tastants?

Answer 14

Sweet (glucose) 
Salty (Sodium ion Na+) 
Umami (glutamate) 
Bitter (quinine) 
Sour (H+)

Question 15

How is salty taste detected?

Answer 15

Sodium channel opens voltage gated Ca2+ channel causing depolarisation which causes neurotransmitter release

Question 16

How is sour taste detected?

Answer 16

H+ sensitive cation channel, H+ blocks K+ channel which prevents K+ from leaving cell causing depolarisation which opens voltage gated Ca2+ channel and causes neurotransmitter release

Question 17

Which tastes are G protein coupled and which are ion channels (passive diffusion)

Answer 17

Bitter, sweet, umami G

Salty and sour ion channels

Question 18

What is the cochlea?

Answer 18

a fluid-filled, membranous sac that is coiled like a snail shell where Sound waves (mechanical stimuli)
are detected

Question 19

What kind of channel is hearing connected with?

Answer 19

Ion channels that are gated by mechanical stress. Depolarisation.

Question 20

What are nociceptors?

Answer 20

Pain receptors

Question 21

Which kinds of nociceptors exist?

Answer 21

Mechanical: touch, pressure
Thermal: heat, cold
Chemical: spices, chemicals