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32 Cards in this Set
- Front
- Back
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What is strabismus? |
Imbalance in the extraocular muscles of the eye |
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What is the term for convergence of the eyes (cross-eyed)? |
Esotropia |
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What is the term for divergence of the eyes? |
Exotropia |
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What is the blind spot also called? |
The optic disk. |
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What is the Macula and what is it characterised by? |
It is the region of the retina for central vision where there are no blood vessels to improve vision quality. |
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Where is the retina thinnest at? |
The Fovea Centralis |
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Where is the Aqueous Humor produced and absorbed? |
Produced in the ciliary body and absorbed by the Canal of Schlemm |
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What are the disorders of the Aqueous humor? |
Glaucoma Cataracts |
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Which of the eye components has the biggest refractive power? Which of the other follows? |
The cornea ~80% of total refraction The lens ~20% of total refraction |
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What is the focal distance? |
Distance between cornea and fovea centralis |
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What is the equation of refractive power and what is it measured in? |
Refractive power (diopters) = 1/ focal distance (m) |
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What happens during accommodation by the lens? |
When the object is far away, the ciliary muscle relaxes, the suspensory ligaments stretch and the lens flttens. The opposite happens when the object is near |
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What characterizes Hyperopia? |
Can’t see things that are far away, the lens is flattened or the eye is too short, the image projects behind the retina, you need convergent glasses to fix it |
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What are the cells of the retina? |
Ganglion cells Amacrine cells Bipolar cells Horizontal cells Photoreceptors |
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What is the laminar organisation of the retina? |
Ganglion cell layer Inner plexiform layer Inner nuclear layer Outer plexiform layer Outer nuclear layer Cones and Rods layer Pigmented cells layer |
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What does the Duplicity Theory entail? |
There cannot be both high sensitivity and high resolution in a single receptor |
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Rod Receptors characteristics |
Greater number of disks Higher photopigment c% 1000x more sensitive to light Low acuity Enable vision in scotopic conditions |
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What is the difference between the central and peripheral retina? |
Central Retina: low convergence (sensitivity) and high resolution Peripheral Retine: high sensitivity and low acuity |
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What are the photopigments for rods and cones? |
Rods: rhodopsin Cones: opsins (S, M, L) |
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Which components of a rod are important in Phototransduction? |
Rhodopsin - activated by light, changes conformation Retinal - inside rhodopsin, reacts to light, changes conformation Transducin - the alfa subunit breaks from it and binds to the PDE protein => converts cGMP to GMP The cGMP gated Na+ channel closes cause there is no more cGMP |
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How does saturation happen? |
It happens in Rods because the cGMP levels are low enough that no additional hyperpolarization can occur |
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What does light adaptation require? |
Calcium |
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Which is the oldest and most common form of sense? |
The chemical sense |
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Which tastes are ionotropic and which ones are metabotropic? |
Ionotropic - Salty, Sour Metabotropic - Sweet, Bitter, Umami |
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Where one the tongue to we perceive different tastes? |
Back (Definition) |
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How many taste buds are there in total? How many taste cells are there per taste bud? |
2000-5000 100 per taste bud |
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What is the transduction mechanism for the different tastes? |
Bitter, sweet, Umami - Metabotropic, uses ATP, no synaptic vesicles Sour - Ionotropic, Synaptic Vesicles, Uses serotonin, GABA, ATP? |
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What is the size of the Human Olfactory Epithelium? |
10cm^2 |
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Transduction occurs via what type of Receptors? How many receptor proteins does a human have? |
Transduction occurs via specific G-protein coupled receptors Humans have ~350 receptor proteins |
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How much of the entire genome is comprised of OR Protein genes? |
~3,5% |
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What’s the role of the pigmented epithelium? |
Critical role in the maintanance of the photoreceptors and photopigments. Also absorbs any light that passes entirely through the retina, minimizing the scattering of light that would blur the image. |
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What are the three different types of cones? |
Blue cones - activated by light with short wavelength of ~430nm Green - medium wavelength of ~530nm Red - long wavelength of about ~560nm |
