Taste and vision Flashcards
(27 cards)
Why do we experience taste?
Drives appetite,
protects us from poisons
Need carbohydrate and protein
Where are taste buds found?
Tongue, epiglotis, soft pallete, laryngeal pharnyx and oral pharynx
What are the three types of papillae where you find taste buds?
Fungiform
Foliate
Circumvalate
Where are fungiform found?
At tip and sides of tongue
Where are foliate found?
Folds on side of tongue
Where are circumvalate found?
At back of tongue
How does taste transduction occur? For salt
Influx of sodium
Taste transduction of sour foods
H+ ions blocks channels in membrane?
Taste transduction sweet bitter umami
Gpcr
Trpm5 ca channels influx
Plc dag and ip3 increases calcium
Depolarisation ect
Subunit for bitter r
T2r and t2r
Subunits for sweet receptor
T1r2 and t1r3
Subunits for umami receptor
T1r1 and t1r3
What is hyperopia?
Cornea/lens too weak or eyeball too short
Image focused behind retina
Far objects are clear, close blurred
What is myopia?
Cornea/lens too powerful or eyeball too long
Images focused in front of retina
Close objects clear, far objects blurred
What is presbyopia
Lens becomes stiffer with age
Near point receds
Far is clear, close blurred
What is astigmatism
Different refractive power for different axes
Cornea has uneven cylindrical curvature
Images blur in one direction only
Correct myopia
Concave
Correct hyperopia
Convex
Correct presbyopia
Convex
Correct astigmatism
Cylindral lens
Rhodopsin
Pigment in rods
7tm domains
Ttm has retinal attacthment site
Phosphorylation sites are on cooh
Retinal in dark
Kinked
Able to bind opsin
Pigment is purple
Retinal in light
Straight retinal detatches from opsin
Visual transduction pathway
Rhodopsin absorbs photon
Retinal isomerised from cis to trans
Rhodopsin now meta 2 activated form
Activates transducin gtp swap
Alpha of transducin activates phosphodiesterase
Each activated pde hydrolyses 200cGMP
CCNG channels close as they need cGMP to stay open
Hyperpolarisation occurs due to decrease in sodium and calcium
