polar body

Examples of polar body in the following topics:

• Oogenesis

  • An important event in the development of the tertiary follicle occurs when the primary oocyte completes the first meiotic division, resulting in the formation of a polar body and a secondary oocyte.
  • When meiosis II has completed, an ootid and another polar body is created.
  • Both polar bodies disintegrate at the end of meiosis II, leaving only the ootid, which eventually develops into a mature ovum.
  • The formation of polar bodies serves to discard the extra haploid sets of chromosomes that have resulted as a consequence of meiosis.

• Heat Conservation and Dissipation

  • Polar bears and seals live and swim in a subfreezing environment, yet they maintain a constant, warm, body temperature.
  • Endotherms use their circulatory systems to help maintain body temperature.
  • For example, vasodilation brings more blood and heat to the body surface, facilitating radiation and evaporative heat loss, which helps to cool the body.
  • Ecothermic animals use changes in their behavior to help regulate body temperature.
  • Describe some of the changes animals use in order to maintain body temperature

• Polarization By Scattering and Reflecting

  • In the previous atom we discussed how polarized lenses work.
  • The reflected light is more horizontally polarized.
  • Just as unpolarized light can be partially polarized by reflecting, it can also be polarized by scattering (also known as Rayleigh scattering; illustrated in ).
  • The light parallel to the original ray has no polarization.
  • The light perpendicular to the original ray is completely polarized.

• Total Polarization

  • When light hits a surface at a Brewster angle, reflected beam is linearly polarized. shows an example, where the reflected beam was nearly perfectly polarized and hence, blocked by a polarizer on the right picture.
  • A polarizing filter allows light of a particular plane of polarization to pass, but scatters the rest of the light.
  • When two polarizing filters are crossed, almost no light gets through.
  • In the picture at left, the polarizer is aligned with the polarization angle of the window reflection.
  • In the picture at right, the polarizer has been rotated 90° eliminating the heavily polarized reflected sunlight.

• Body-Oriented Psychotherapies

  • Body-oriented psychotherapies focus on the importance of working with the body in the treatment of mental health issues.
  • Body-oriented therapies, also referred to as body psychotherapies, are based on the principles of somatic psychology, which involves the study of the body, somatic experience, and the embodied self, including therapeutic and holistic approaches to the body.
  • A wide variety of techniques are used in body-oriented therapies, including sound, touch, mirroring, movement, and breath.
  • Light therapy (also known as phototherapy or heliotherapy) consists of exposure to daylight or to specific wavelengths of light using polychromatic polarized light, fluorescent lamps, or very bight, full-spectrum light.
  • Reich's work significantly influenced the development of body psychotherapy; several types of body-oriented psychotherapies trace their origins back to Reich, though there have been many subsequent developments and additional influences.

• Polarization By Passing Light Through Polarizers

  • Since the direction of polarization is parallel to the electric field, you can consider the blue arrows to be the direction of polarization.
  • What happens to these waves as they pass through the polarizer?
  • Lets call the angle between the direction of polarization and the axis of the polarization filter θ.
  • If you pass light through two polarizing filters, you will get varied effects of polarization.
  • A polarizing filter has a polarization axis that acts as a slit passing through electric fields parallel to its direction.

• Bond Polarity

  • Molecular polarity is dependent on the presence of polar covalent bonds and the molecule's three-dimensional structure.
  • Such bonds are said to be 'polar' and possess partial ionic character.
  • Molecular polarity: when an entire molecule, which can be made out of several covalent bonds, has a net polarity, with one end having a higher concentration of negative charge and another end having a surplus of positive charge.
  • A polar molecule acts as an electric dipole which can interact with electric fields that are created artificially, or that arise from interactions with nearby ions or other polar molecules.
  • The water molecule, therefore, is polar.

• Bond Polarity

  • Bond polarity exists when two bonded atoms unequally share electrons, resulting in a negative and a positive end.
  • Bonds can fall between one of two extremes, from completely nonpolar to completely polar.
  • The terms "polar" and "nonpolar" usually refer to covalent bonds.
  • To determine the polarity of a covalent bond using numerical means, find the difference between the electronegativity of the atoms; if the result is between 0.4 and 1.7, then, generally, the bond is polar covalent.
  • The hydrogen fluoride (HF) molecule is polar by virtue of polar covalent bonds; in the covalent bond, electrons are displaced toward the more electronegative fluorine atom.

• Fluid Mosaic Model

  • Hydrophobic, or water-hating molecules, tend to be non-polar.
  • They interact with other non-polar molecules in chemical reactions, but generally do not interact with polar molecules.
  • The hydrophilic regions of the phospholipids tend to form hydrogen bonds with water and other polar molecules on both the exterior and interior of the cell.
  • This recognition function is very important to cells, as it allows the immune system to differentiate between body cells (called "self") and foreign cells or tissues (called "non-self").
  • In an aqueous solution, phospholipids tend to arrange themselves with their polar heads facing outward and their hydrophobic tails facing inward.

• Introduction to the Polar Coordinate System

  • Polar coordinates are points labeled $(r,θ)$ and plotted on a polar grid.
  • In mathematical literature, the polar axis is often drawn horizontal and pointing to the right.
  • The polar grid is scaled as the unit circle with the positive $x$-axis now viewed as the polar axis and the origin as the pole.
  • Even though we measure $θ$ first and then $r$, the polar point is written with the $r$ -coordinate first.
  • Points in the polar coordinate system with pole $0$ and polar axis $L$.