Müller glia, or Müller cells, are a type of retinal glial cells in the human eye that serve as support cells for the neurons, as other glial cells do.
- An important role of Müller cells is to funnel light to the rod and cone photoreceptors from the outer surface of the retina to where the photoreceptors are located.
- Other functions include maintaining the structural and functional stability of retinal cells. They regulate the extracellular environment, remove debris, provide electrical insulation of receptors and other neurons, and mechanical support of the neural retina.
- All glial cells (or simply glia), are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system.
- Müller cells are the most common type of glial cell found in the retina. While their cell bodies are located in the inner nuclear layer of the retina, they span the entire retina.
Momentum is a measure of how much mass an object has and how fast it is moving. It is calculated by multiplying the mass of the object by its velocity.
- Momentum is a vector quantity, which means that it has both magnitude and direction.
- Momentum = mass x velocity.
- Momentum is conserved, which means that the total momentum of a system remains constant unless an external force acts on the system.
- Momentum can only be transferred between objects, not created or destroyed.
- Examples of momentum:
- A bowling ball has more momentum than a baseball because it has more mass.
- A car moving at 60 mph has more momentum than a car moving at 30 mph.
- A rocket launching into space has a lot of momentum because it has a lot of mass and it is moving very fast.
Monochromatic refers to light or electromagnetic radiation that consists of a single wavelength or frequency. In simpler terms, monochromatic light is composed of just one colour. The term comes from the Greek words mono (meaning “one”) and chroma (meaning “colour”).
- Monochromatic colours are created by using variations of a single hue, incorporating both shades (by adding black) and tints (by adding white). For example, a monochromatic colour scheme could involve a range of blues or pinks.
- It’s important not to confuse monochrome with greyscale. Monochrome refers to variations of a single hue, which can include any colour. In contrast, greyscale consists solely of shades of grey, with no colour information.
- In physics, monochromatic light refers to visible light or other electromagnetic radiation that has a single wavelength or frequency, resulting in light of a single colour.
- A surface or material is considered monochromatic if it features only one hue or a combination of tints and shades of the same colour.
The term metameric refers to visually indistinguishable colour stimuli that appear the same but have different spectral compositions are called metameric.
- Metameric stimuli are colour stimuli that are indistinguishable from one another because they produce the same responses from the three types of cone cells in the human eye that are responsible for colour vision.
- Metameric matches can occur in different parts of the spectrum, which means that the spectral power distributions of different light sources can look similar, but not identical, to one another.
- A class of metameric stimuli can be specified by a set of tristimulus values, which represent the amounts of three reference colours, typically red, green, and blue, in a given trichromatic system, that are required to match the colour of the stimulus considered.
- The most important application of metameric stimuli is in the use of tristimulus values for additive colour mixing, such as in computer displays and TVs.
- The RGB colour model, for example, uses mixtures of red, green, and blue light to produce a wide range of colours visible to an observer.
In physics and optics, a medium refers to any material through which light or other electromagnetic waves can travel. It’s essentially a substance that acts as a carrier for these waves.
- Light is a form of electromagnetic radiation, which travels in the form of waves. These waves consist of oscillating electric and magnetic fields.
- The properties of the medium, such as its density and composition, influence how light propagates through it.
- Different mediums can affect the speed, direction, and behaviour of light waves. For instance, light travels slower in water compared to a vacuum.
- Examples of Mediums:
- Transparent: Materials like air, glass, and water allow most light to pass through, with minimal absorption or scattering. These are good examples of mediums for light propagation.
- Translucent: Some materials, like frosted glass or thin paper, partially transmit light. They allow some light to pass through while diffusing or scattering the rest.
- Opaque: Materials like wood or metal block light completely. They don’t allow any light to travel through them.
Matter is anything that has mass and energy and occupies space by virtue of having volume.
- Matter is the substance that makes up all physical objects and substances in the universe, including solids, liquids, and gases.
- Matter is made up of atoms, which may combine to form molecules. Atoms in turn consist of subatomic particles such as protons, neutrons, and electrons.
- Subatomic particles have mass and may have energy.
- Matter can undergo physical and chemical changes, but the total amount of matter in a closed system remains constant (Law of Conservation of Matter). This means that matter cannot be created or destroyed in chemical reactions, only transformed into different forms.
- Light is a form of electromagnetic radiation, which does not have mass and is not considered matter.
- light interacts with matter (e.g., through absorption, reflection, and transmission), but is not composed of particles with mass.
A material thing is made up of matter, which includes all substances that have mass and occupy space. Matter is composed of atoms and molecules, and its properties include mass, volume, and density.
- Material things include objects, living organisms, and even intangible things such as sound or light, which are considered material because they are made up of particles.
- An attribute of an object is called a property if it can be measured or observed through the senses (e.g. its colour, size, weight, odour, taste, and location).
- Objects can be identified or characterized through their properties, which manifest themselves in various ways.
- These manifestations often exhibit consistent patterns, indicating that there is a underlying cause or mechanism that governs the properties:
- For example when different metals are mixed to form alloys, such as bronze or steel, the resulting material often exhibits a consistent relationship between its composition (the types and proportions of metals) and its density. So increasing the percentage of a denser metal in an alloy tends to increase its overall density.
A material is the substances or matter that a thing is made of.
- Material is a broad term for a chemical substance or mixture of substances that constitute an object.
- Materials are composed of atoms and molecules arranged in various configurations, which determine their properties and behaviour.
- Materials can have natural origins, such as wood, stone, and metals, or synthetic origins, such as polymers and ceramics. Materials can also be classified based on whether they are organic or inorganic.
- The properties of a material depend on its structure at different length scales, from atomic to macroscopic scales.
- Materials can be classified based on physical and chemical properties such as mechanical, thermal, electrical, and magnetic properties.
- Materials are studied in materials science, a branch of engineering that focuses on structure, properties, and processing.
Mass is a fundamental property of matter and is defined as the amount of matter present in an object and is independent of external factors such as location or the presence of gravitational fields.
- A large object made of a given material has greater mass than a small object made of the same material because it contains more matter.
- Mass is not the same as weight because weight varies with gravity while mass remains constant.
- Weight is the force exerted on an object due to gravity:
- An object of a known mass weighs more on earth than on the moon due to differences in gravity.
Müller cells
Müller glia, or Müller cells, are a type of retinal cell that serve as support cells for neurons, as other types of glial cells do.
An important role of Müller cells is to funnel light to the rod and cone photoreceptors from the outer surface of the retina to where the photoreceptors are located.
Other functions include maintaining the structural and functional stability of retinal cells. They regulate the extracellular environment, remove debris, provide electrical insulation of the photoreceptors and other neurons, and mechanical support for the fabric of the retina.
- All glial cells (or simply glia), are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system.
- Müller cells are the most common type of glial cell found in the retina. While their cell bodies are located in the inner nuclear layer of the retina, they span the entire retina.