diameter

(noun)

Two times the radius of a circle.

Related Terms

Examples of diameter in the following topics:

  • Arterioles

    • An arteriole is a small diameter blood vessel in the microcirculation system that branches out from an artery and leads to capillaries.
    • An arteriole is a small-diameter blood vessel which forms part of the microcirculation that extends from an artery and leads to capillaries.

  • Capillaries

    • Capillaries, which form part of the micro-circulation, are the smallest of the body's blood vessels at between 5-10 μm in diameter with the endothelial vessel wall of only one cell thick.
    • Fenestrated - Fenestrated capillaries have pores in the endothelial cells (60-80 nanometers in diameter) that are spanned by a diaphragm of radially-oriented fibrils.
    • Sinusoidal - Sinusoidal capillaries are a special type of fenestrated capillaries that have larger openings (30-40 μm in diameter) in the endothelium.
    • These types of blood vessels allow red and white blood cells (7.5μm - 25μm diameter) and various serum proteins to pass using a process aided by a discontinuous basal lamina.
    • Capillaries are of small diameter with the vessel wall being a single cell thick.

  • Classification of Nerves

    • Peripheral nerve fibers are grouped based on the diameter, signal conduction velocity, and myelination state of the axons.
    • Fibers of the A group have a large diameter, high conduction velocity, and are myelinated.
    • Fibers of the B group are myelinated with a small diameter and have a low conduction velocity.
    • Fibers of the C group are unmyelinated, have a small diameter, and low conduction velocity.

  • Gas Vesicles

    • There is a simple relationship between the diameter of the gas vesicle and pressure at which it will collapse - the wider the gas vesicle the weaker it becomes.
    • Different species produce gas vesicles of different diameters, allowing them to colonize different depths of the water column (fast growing, highly competitive species with wide gas vesicles in the top most layers; slow growing, dark-adapted, species with strong narrow gas vesicles in the deeper layers).
    • The diameter of the gas vesicle will also help determine which species survive in different bodies of water.

  • Eukaryotic Chromosomal Structure and Compaction

    • However, the diameter would be only 2 nm.
    • The beads are about 10 nm in diameter, in contrast with the 2-nm diameter of a DNA double helix.
    • The conjoined sister chromatids, with a diameter of about 1 µm, are visible under a light microscope.

  • Velocity of Blood Flow

    • Resistance is the force that must be overcome by pressure in order for flow to occur, and is a factor of vessel length, diameter, surface composition, and the viscosity of the liquid flowing through.
    • Blood vessels are capable of vasodilation and vasoconstriction to alter their diameter.
    • Assuming all else remains equal, a reduction in diameter results in a reduction in flow, whereas an increase in vessel diameter results in an increase in flow.

  • Circles as Conic Sections

    • The ratio of a circle's circumference to its diameter is π (pi), an irrational constant approximately equal to 3.141592654.
    • The length of the circumference, C, is related to the radius, r, and diameter, d, by:
    • Diameter: the longest chord, a line segment whose endpoints lie on the circle and which passes through the center; or the length of such a segment, which is the largest distance between any two points on the circle.
    • Radius: a line segment joining the center of the circle to any point on the circle itself; or the length of such a segment, which is half a diameter.

  • The Rayleigh Criterion

    • Calculate the minimum angular spreading of a flashlight beam that is originally 5.00 cm in diameter with an average wavelength of 600 nm.
    • θ - angle the objects are separated by, in radian λ - wavelength of light D - aperture diameter. shows this concept visually.
    • This equation also gives the angular spreading of a source of light having a diameter D.

  • Study Questions

    • I have two populations of ten actors each, one has a network diameter of 3, the other has a network diameter of 6.
    • Can you explain why this difference in diameter might be important in understanding differences between the two populations?

  • Components of Blood

    • Erythrocytes are discs measuring about seven to eight micrometers in diameter.
    • Leukocytes are usually larger in size (10-14 micrometers in diameter) than red blood cells.
    • Thrombocytes measure between one to two micrometers in diameter.