Physiology Flashcards
(56 cards)
refractory power sum of the eye and the main cotributor is:
59 diopters and the cornea
lenns refractive power is:
20 and changes to 34 when accommidation
the light rays of close objects fall behind the retina in ____ meanwhile in front for far objects in the _______
hypermetropic
myotropic (too srtong eye lens or long eye. ball)
the type of lenses that are used for myopic and hyperopia and astigmatism and keratooconus
concave and convex
cylindrical lens
lenses
uneven irrigular curvature of the cornea. is seen ______
buldgin of the cornea is. ____
astigmatism
keratoconus
when there is no accommodation :
ciliary muscles are relaxed and zonula fibers are stretched and an open iris
accommodation is linked to
convergence of the eyes and constriction of the pupil
intraocular pressure is ____ and abnormal elevation of it causes ____ and the rate of humor production is:
15 mmHg
glucoma
2-3microliter \ minuets
location of the optic disc and fovea
nasal part of the retina and has no photoreceptor
temporal to optic disc and has highest visual activity. containing many cones and less rods.
layers of retina are pushed aside resulting in less light scattering , absence of of blood vessels, connection between foveal cones and. ganglion, lower ratio of cones:ganglions and yellow pigmented
fovea centralis
pupil diameter ranger from ___ to ____ and the square of this diameter tells us the amount of light, of can go from ____ to _____
1.5 - 8
2.25 - 64
blood supply of the retina
inner two thirds by the central retina
outer third by the inner vascular choroid
horizontal and amarcine cells functions
inhibition to enhance contrast
light turn on and off and light movement respond
in rods, what are the type of photopigment and protein of pigment , how is it distributed and excitation duration and sensitivity to light and adaptation to dark
same for the cones
rhodopsin, scotopsin ,periphery , needs more time and high sensitivity slow
color pigment , photopsin , fovea, less time and less sensitivity fast
induction of signals of the light
rhodopsin (11 cis retinal + protein) > metarhodopsin 2 > phosphodiesterase > less cGMP > closure of Na channels and hyperpolarization > no inhibitory NT
metarhodopsin 2 pathway for vit A formation
break down into all trans retinal + protein > 11 cis retinal > used again
break down into all trans retinal + protein > all trans retinol (vit A) > 11 cis retinol > 11 cis retinal
adaptation of eyes to dark and light
- more photochemicals ands Vit A converted to retinal form and increase in pupil size
- less photochemical , retinal converted to vit A, more vit A concentration
ganglion cell that is small, velocity = 8, crude rod vision and directional movements
w ganglion cells
ganglion cells that are medium with 14 velocity and transmit colors
X ganglion cells
ganglion cells that are large , 50 is its velocity
- detect lights density
- detects rapid movements
- black and white vision
Y ganglion cells
Lateral geniculate body branches are:
receives info from:
suprechiasmic ( biological clock) , pretectal (light reflex and focus on objects) , superior colliculus
visual cortex , mesencephalon, optic erve
layers of the geniculate body and their innervation of the visual cortex
- magnocellular (1+2) : receive from Y and blind vision»_space; innervate to C alpha
- parvocellular (3 > 6) : receive from x and colored »_space; innervates to A, C beta , blob
secondary visual cortex divisions and functions
- dorsal stream
WHERE , 3D image and motion, uses black and white - ventral stream
WHAT, lateral occipital complex for objects and inferior temporal for faces , colored vision
The softest audible sound is _ db (absolute threshold)
Normal conversation is _ db
Discomfort & damage to hearing receptors occurs at _ db
Pain occurs at _ db
0
60
140
160
the total amplification of sound is — and the tympanic membrane contributes _ meanwhile ossicles amplify.
times
22 times
17 times
1.3 times
