Physiology Of Vision Flashcards
What is a particle of light called
Photon
What is the function of the lens
Focuses light onto the retina
What is the function of the cornea
Refracts light entering eye
What is lens accomidation
Process where lens curve increases or decreases to focus on an object
How does the lens change shape
Ciliary muscles contract
How do ciliary muscles attach to the lens
By Zonalas (suspensory ligament)
How does the pupil dilate
Radial fibres in iris
How does the pupil constrict
Circular fibres in iris
Unlike ocular humour, which humour is not constantly replaced
Vitreous humour
Which photoreceptor cells are used for bright light
Cones
What type of cells are found in the middle layer of the retina
Internet Ron
Which layer of the retina are rods and cones found
Outer layer
What cells are found in the inner layer of the retina
Ganglion cells
What is the optic disc
Blind spot with no photoreceptor cells as is where the optic nerve leaves the eye and blood vessels enter
Name the internet Ron cells in the middle layer of the retina
Bipolar neutrons
Horizontal neutrons
Amacrine cells
What is the function of interneurons
Connect sensory cells and ganglion axons
What is the function of the Macula Lutea
Part of the retina is responsible for detailed vision due to the presence of the Fova Centralis (high conc of photoreceptor cells)
Name the photosynthetic pigments found rods and cones
11- cis retinal
All-trans retinal
How do rods and cones react to light
Get hyperpolarised
(Light removes cGMP, closes CNG channels, hyper-polarises membrane)
Describe how an image is formed
Light passes through cornea
Pass through pupil (size gets altered by radial and circular smooth muscles)
Light strikes lens (curve altered by ciliary muscle in order to converge light onto retina)
Strikes retina and hit photoreceptor cells
Nerve impulses sent from optic nerve to cerebral hemisphere
(Some light reflected back at Tapetum Lucidum in low light)
How does the brain process the image from the retina
Inverts it to the correct way using other senses