Eye
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Sclera
White of eye Protects and maintains eye shape Becomes cornea
Cornea
Focused bending light towards pupil and protect (no blood supply nutrient obtained from aqueous humour)
Aqueous humid
Maintains shape, nourishes cornea and focus light
Iris
Muscular coloured part
Ciliary muscle
Adjusts shape of lens (accommodation)
Vitreous Humour
Maintains shape and light focus
Retina
Back of eye w photoreceptors
Choroid coat
Below sclera Contains blood vessels and black pigment making eye interior look black and prevents light from scattering
Conjunctiva
Thin membrane w lots of blood vessels
Fovea centeralis
High cone density=detailed vision
Focusing
Light is focused on retina but clearest image on fovea Image is mirrored and upside down
Accommodation
Changing lens shape to focus Far- ciliary muscle relax= lens thin and flat Near- Cm contract= lens fat and round
Compare and contrast rods and cones (Location in retina, Optimal light, Visual acuity, Colour sensitivity, Type of vision, # of types, Abundance)
Rods: Location in retina- Periphery Optimal light- Dim Visual acuity- Low resolution (many rods: 1 bipolar cell) Colour sensitivity- All wavelengths Type of vision- Acromatic # of types- One contain rhodopsin Abundance- Many Location in retina- Fovea Optimal light- Bright Visual acuity- High resolution (1 cone:1 bipolar cell) Colour sensitivity- red green and blue Type of vision- colour # of types- 3 iodopsin pigments Abundance- fewer
Why are rods effective in dim light
Sensitive to light (bright light=temporary bleaching)
What happens when light hits rhodopsin (what is its composition) in rods
When light hits Rhodopsin (retinene (vitamin a derivative and opsin) its splits apart= transmission of inhibitory neuroTM stopped allowing AP
How do cones work and their composition
Made of photopsin/ iodopsin (red green blue) Less light sensitive so it needs a lot of light hence it works in bright light Each cone stimulated at diff wavelength
What do rods and cones synapse w
Bipolar cells
What happens when rods and cones are stimulated bs unstimulated
Not stimulated- releases inhibitory neuroTM and hyper polarizes bipolar cell so no signal is sent to ganglion If stimulated no inhibitory signal sent to ganglion are activated
Transmission of light
Direction of light in retina: Ganglia to bipolar cell to photoreceptors Direction of impulse: Photoreceptors to bipolar cells to ganglion cell Brain: Optic nerve to lateral geniculate nucleus to visual cortex nucleus
Ganglion cells
Send signal to brain by optic nerve (blind spot) It’s dendrites synapse w bipolar cells It’s axon pass through retina where it meets optic
Transmitting signal to brain
Left occipital loves gets info from right part of vision
Function of bipolar cells
Intermediate between photoreceptors and ganglion