Sensory System Lecture 12

Question 1

what are the 5 different modalities

Answer 1

• somatorsensory
• hearing
• taste
• smell
• vision

Question 2

Olfaction

Answer 2

odorants bind to receptors on the olfactory receptor cell

Question 3

Olfactory receptor cells

Answer 3

are bipolar neurons with cilia on dendritic

• cilia contains receptors that bind with specific odorant molecules
• odorants diffuse through mucus and bind to specific receptors
• odorants activate g protein coupled receptors

Question 4

Role of cAMP and how its activated

Answer 4

are important for signaling molecule and for producing ATP

• an odorant molecule to a membrane receptor activates a G-protein which in turns activates the enzyme adenylate cyclase
• Ca2+ and Na+ go into the cell —> depolarizes it

Question 5

Vision

Answer 5

Tranduction of light waves into action potentials

Question 6

parts of the eye

Answer 6

eye: where light passes through to the retina
fovea: where light actually focuses
optic disk: blind spots

Question 7

refraction of light waves

Answer 7

bind light/ allows to focus on the back of the eye

Question 8

Retina

Answer 8

is organized inside out and contains photoreceptor cells (rods, cones)

Question 9

rods

Answer 9

light or absence of light (black and white vision) 
located in the retina 
- very stesntive to light 
contain rhodospin ( photopigment )
Rhodopsin is opsin + retinal

Question 10

cones

Answer 10

color vision ( three kinds of photopigment)
- less sensitive to light
- 3 million per retina
located at the fovea

Question 11

optic disk

Answer 11

cannot perceive any light. where the atoms of the optic nerve exit the eye so no photoreceptors

Question 12

cones 3 different photopigment

Answer 12

1. blue: S Opsin
2. green: M Opsin
3. red : L Opsin

respond to different wavelengths of light
blue= short wavelengths
green = medium wavelengths
red = large wavelengths

Question 13

photopigment

Answer 13

allows different wavelengths or light into the retina

• are molecules that absorbs light
• components of photopigment molecule contains a protein called retinal and a protein called opsin.

Question 14

how does light activate a photopigment

Answer 14

when it is aborted by light, the retinal component changes its conformation and dissociates from the opsin

Question 15

photoreceptors in the light

Answer 15

in the presence of light –> photoreceptors are hyperpolarized

1. Rhosopsin activated, Activates transductin
2. phosphodiesterase is activated, breaks down cGMP
3. Na+ channels close, cell hyperpolarizes
4. Ca2+ channels close
5. decreased neurotransmitters release

Question 16

neurotransmitters in the dark/ light

Answer 16

light= not releasing 
dark = releasing neurotransmitters

Question 17

photoreceptor

Answer 17

is a neurotransmitters= glumate

- binds to a metabrotroic receptors on bipolar cells

Question 18

photopigment bleached? `

Answer 18

if all the photopigments have responded and changed shape then they cant respond anymore

• have to be concerted back to the original shape before they can respond again .

Question 19

why is gustation so limited when compared to olfaction because

Answer 19

receptors only bind to one type of odorant allows us to discrimination between 300,000 smells

Question 20

what structure is responding to cones

Answer 20

It is possible to see different colors by the stimulating of different combinations of iodopsin

Question 21

how to perceive odors

Answer 21

odorants must transverse the mucus layer and bind to olfactory receptors

Question 22

what do the amarcine cells and the horizontal cells do

Answer 22

presented in the middle layer of the retina and are neurons that modulate communication between the cells in the retina

Question 23

what do ganglion cells do in our retina

Answer 23

first neurons in the visual pathways. that are capable of transmitting action potentials

Question 24

what do bipolar cells do in our retina

Answer 24

cable of transmitting graded potential