luteal phase

Examples of luteal phase in the following topics:

• Ovarian Cycle

  • The menstrual cycle is the scientific term for the physiological changes that occur in fertile women for the purpose of sexual reproduction.The menstrual cycle is controlled by the endocrine system and commonly divided into three phases: the follicular phase, ovulation, and the luteal phase.
  • The luteal phase (or secretory phase) is the latter part of the menstrual or estrous cycle.
  • The main hormone associated with this stage is progesterone, which is significantly higher during the luteal phase than in other phases of the cycle.
  • Some sources define the end of the luteal phase as a distinct ischemic phase.
  • Continued drops in estrogen and progesterone levels trigger the end of the luteal phase, menstruation, and the beginning of the next cycle.

• Hormonal Regulation of the Female Reproductive Cycle

  • The menstrual cycle is divided into three stages: follicular phase, ovulation, and the luteal phase.
  • This also causes endometrial cells to produce receptors for progesterone, which helps prime the endometrium to the late proliferative phase and the luteal phase.
  • The luteal phase begins with the formation of the corpus luteum stimulated by FSH and LH and ends in either pregnancy or luteolysis.
  • The main hormone associated with this stage is progesterone, which is produced by the growing corpus luteum and is significantly higher during the luteal phase than other phases of the cycle.
  • The death of the corpus luteum results in falling levels of progesterone and estrogen, which triggers the end of the luteal phase.

• Periodic Abstinence

  • The Knaus–Ogino method, or rhythm-method, works by using the the estimated length of the pre-ovulatory infertile phase, nineteen (19), subtracted from the length of the woman's shortest cycle.
  • To find the estimated start of the post-ovulatory infertile phase, ten (10) is subtracted from the length of the woman's longest cycle.
  • The postovulatory (luteal) phase has a normal length of 12 to 16 days, and the rhythm method formula assumes that all women have luteal phase lengths within this range.
  • However, many women have shorter luteal phases, and a few have longer luteal phases.
  • If she has an unusually early ovulation, calendar-based methods will indicate she is still in the pre-ovulatory infertile phase when she has actually become fertile.

• Premenstrual Syndrome and Premenstrual Dysphoric Disorder

  • While most women of child-bearing age (up to 85%) report having experienced physical symptoms related to normal ovulatory function, such as bloating or breast tenderness, medical definitions of PMS are limited to a consistent pattern of emotional and physical symptoms occurring only during the luteal phase of the menstrual cycle that are of sufficient severity to interfere with some aspects of life.
  • It is a diagnosis associated primarily with the luteal phase of the menstrual cycle.
  • Up to one-third of women diagnosed with premenstrual dysphoric disorder (PMDD) report residual symptoms into the first two or three days of the follicular phase.
  • Symptoms begin in the late luteal phase of the menstrual cycle (after ovulation) and end shortly after menstruation begins.

• Female Hormones

  • The first half of the ovarian cycle is the follicular phase.
  • After about five days, estrogen levels rise and the menstrual cycle enters the proliferative phase.
  • Following ovulation, the ovarian cycle enters its luteal phase and the menstrual cycle enters its secretory phase, both of which run from about day 15 to 28.
  • The luteal and secretory phases refer to changes in the ruptured follicle.
  • The pattern of activation and inhibition of these hormones varies between phases of the reproductive cycle.

• Interpreting Phase Diagrams

  • The lines that separate these single phase regions are known as phase boundaries.
  • By focusing attention on distinct single phase regions, phase diagrams help us to understand the range over which a particular pure sample of matter exists as a particular phase.
  • When evaluating the phase diagram, it is worth noting that the solid-liquid phase boundary in the phase diagram of most substances has a positive slope.
  • With a knowledge of the major components of phase diagrams and the features of phase plots, a phase diagram can be used to understand how altering thermodynamic parameters influences the states/phases of matter a sample of a substance is in.
  • A typical phase diagram illustrating the major components of a phase diagram as well as the critical point.

• Major Features of a Phase Diagram

  • A phase diagram is a graph which shows under what conditions of temperature and pressure distinct phases of matter occur.
  • The simplest phase diagrams are of pure substances.
  • The major features of a phase diagram are phase boundaries and the triple point.
  • Phase boundaries, or lines of equilibrium, are boundaries that indicate the conditions under which two phases of matter can coexist at equilibrium.
  • In this phase diagram, which is typical of most substances, the solid lines represent the phase boundaries.

• Solid to Gas Phase Transition

  • Sublimation is the phase transition from the solid to the gaseous phase, without passing through an intermediate liquid phase.
  • Sublimation is the process of transformation directly from the solid phase to the gaseous phase, without passing through an intermediate liquid phase.
  • It is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point (the temperature and pressure at which all three phases coexist) in its phase diagram.
  • But at temperatures below that of the triple point, a decrease in pressure will result in a phase transition directly from the solid to the gaseous.
  • At temperatures and pressures below those of the triple point, a phase change between the solid and gas phases can take place.

• Phase-Contrast Microscopy

  • In phase-contrast microscopy, parallel beams of light are passed through objects of different densities.
  • A phase ring in condenser allows a cylinder of light to pass through it while still in phase.
  • Unaltered light hits the phase ring in the lens and is excluded.
  • Phase-contrast images have a characteristic grey background with light and dark features found across the sample.
  • One disadvantage of phase-contrast microscopy is halo formation called halo-light ring.

• The Evaporating Atmosphere

  • Within each phase, the properties are uniform but between the two phases properties differ.
  • Water in a closed jar with an air space over it forms a two phase system.
  • Even at equilibrium, molecules are constantly in motion and, once in a while, a molecule in the liquid phase gains enough kinetic energy to break away from the liquid phase and enter the gas phase.
  • The water vapor in it changes phases.
  • It is in a phase equilibrium.