Sensory System Lecture 12 Flashcards
what are the 5 different modalities
- somatorsensory
- hearing
- taste
- smell
- vision
Olfaction
odorants bind to receptors on the olfactory receptor cell
Olfactory receptor cells
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
Role of cAMP and how its activated
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
Vision
Tranduction of light waves into action potentials
parts of the eye
eye: where light passes through to the retina
fovea: where light actually focuses
optic disk: blind spots
refraction of light waves
bind light/ allows to focus on the back of the eye
Retina
is organized inside out and contains photoreceptor cells (rods, cones)
rods
light or absence of light (black and white vision) located in the retina - very stesntive to light contain rhodospin ( photopigment ) Rhodopsin is opsin + retinal
cones
color vision ( three kinds of photopigment)
- less sensitive to light
- 3 million per retina
located at the fovea
optic disk
cannot perceive any light. where the atoms of the optic nerve exit the eye so no photoreceptors
cones 3 different photopigment
- blue: S Opsin
- green: M Opsin
- red : L Opsin
respond to different wavelengths of light
blue= short wavelengths
green = medium wavelengths
red = large wavelengths
photopigment
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.
how does light activate a photopigment
when it is aborted by light, the retinal component changes its conformation and dissociates from the opsin
photoreceptors in the light
in the presence of light –> photoreceptors are hyperpolarized
- Rhosopsin activated, Activates transductin
- phosphodiesterase is activated, breaks down cGMP
- Na+ channels close, cell hyperpolarizes
- Ca2+ channels close
- decreased neurotransmitters release
neurotransmitters in the dark/ light
light= not releasing dark = releasing neurotransmitters
photoreceptor
is a neurotransmitters= glumate
- binds to a metabrotroic receptors on bipolar cells
photopigment bleached? `
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 .
why is gustation so limited when compared to olfaction because
receptors only bind to one type of odorant allows us to discrimination between 300,000 smells
what structure is responding to cones
It is possible to see different colors by the stimulating of different combinations of iodopsin
how to perceive odors
odorants must transverse the mucus layer and bind to olfactory receptors
what do the amarcine cells and the horizontal cells do
presented in the middle layer of the retina and are neurons that modulate communication between the cells in the retina
what do ganglion cells do in our retina
first neurons in the visual pathways. that are capable of transmitting action potentials
what do bipolar cells do in our retina
cable of transmitting graded potential
