Glossary
Amacrine cells
Amacrine cells are located in the inner plexiform layer of the retina and provide 70% of the input to retinal ganglion cells (Bipolar cells are responsible for the other 30%; however, these are regulated by amacrine cells). There are around 40 different types of amacrine cells and like...
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Bipolar cells
Bipolar cells act to directly or indirectly transmit signals from photoreceptors to the ganglion cells. They are named due to having two sets of processes arising from their cell body. They can make synapses with either rod cells or cone cells and also receive information from horizontal cells. The...
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Ganglion cells
Retinal ganglion cells are a type of neuron located on the inner surface of the retina. They receive information from photoreceptors by two types of the cells; the bipolar and amacrine cells. They then transmit this information to different parts of the brain, including the midbrain, thalamus...
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Horizontal cells
Horizontal cells are located in the outer plexiform layer of the retina and are laterally connecting neurons. They help to regulate and integrate the information from photoreceptors. They also have a role in allowing the eyes to adjust in both bright and dim light. There are three types of...
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Macula
The macula is oval-shaped highly pigmented yellow spot near the centre of the retina of the human eye. It has a diameter of around 5mm and is often histologically defined as having two or more layers of ganglion cells. Near its centre is the fovea, a small pit which contains the largest...
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Melanin
Melanin is present in plants and animals where it forms a class of compounds which serve mainly as a pigment. They are derived from the amino acid tyrosine and many are insoluble salts which show affinity to water. Melanin is an excellent photoreactant as it absorbs harmful UV-radiation and...
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Photopsins
Photopsins (also known as iodopsins) are the photoreceptor proteins found in the cone cells of the retina. Photopsins are close analogues of the pigment rhodopsin, however, they are used in colour vision instead of night vision.
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Retinal
Retinal is a polyene chromophore which is bound to proteins called opsins and provides the chemical basis for animal vision. It can also be callled retinaldehyde or vitamin A aldehyde and it is one of three forms of vitamin A. Retinal is bound to type 1 rhodopsins and it allows organisms to convert...
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Rhodopsin
Rhodopsin is a member of the G-protein coupled receptor family. It is a pigment in the retina which is responsible for both the formation of photoreceptor cells and the first perceptions of light. It is extremely sensitive to light which enables viewing in low light conditions. When exposed to...
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Ringer's lactate
Ringer’s lactate is a solution which is isotonic with blood. One litre of lactated Ringer's solution contains:
130 mEq of sodium ion = 130 mmol/L.
109 mEq of chloride ion = 109 mmol/L.
28 mEq of lactate = 28 mmol/L.
4 mEq of potassium ion = 4 mmol/L.
3 mEq of calcium ion = 1.5...
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Did you know..
The eye can process 36,000 pieces of information every hour.