Luteinizing hormone

Examples of Luteinizing hormone in the following topics:

• Hormonal Regulation of the Male Reproductive System

  • Hormonal control of spermatogenesis varies among species.
  • They are capable of producing the hormones estradiol and inhibin.
  • There it stimulates the synthesis and secretion of the gonadotropins, FSH and luteinizing hormone (LH).
  • Follicle-stimulating hormone (FSH)  is released by the anterior pituitary gland.
  • Luteinizing hormone (LH) is released by the anterior pituitary gland.

• Onset, Duration, and Half-Life of Hormone Activity

  • A hormone's half-life and duration of activity are limited and vary from hormone to hormone.
  • A hormone's half-life and duration of activity are limited and vary from hormone to hormone.
  • For instance, the biological half-life of luteinizing hormone is 20 minutes, which is shorter than that of a follicle-stimulating hormone (three to four hours), and of human chorionic gonadotropin (24 hours).
  • Follicle-stimulating hormone 2.
  • Luteinizing hormone 4.

• Hormonal Regulation of the Female Reproductive Cycle

  • The menstrual cycle is controlled by a series of changes in hormone levels, primarily estrogen and progesterone.
  • Follicle-stimulating hormone (FSH) is secreted by the anterior pituitary gland.
  • Follicle-stimulating hormone induces the proliferation of granulosa cells in the developing follicles and the expression of luteinizing hormone (LH) receptors on these cells.
  • Luteinizing hormone induces androgen synthesis by theca cells, stimulates proliferation, differentiation, and increases LH receptor expression on granulosa cells.
  • The surge also initiates luteinization of theca and granulosa cells.

• Oogenesis

  • At the start of the menstrual cycle, some 12-20 primary follicles begin to develop under the influence of elevated levels of follicle-stimulating hormone (FSH) to form secondary follicles.
  • On day 14 of the cycle, a luteinizing hormone surge is triggered by the positive feedback of estrogen.
  • Differentiate among the stages of oogenesis and the actions of hormones during each stage

• The Anterior Pituitary

  • Thyroid-stimulating hormone is a glycoprotein hormone that affects the thyroid gland and the secretion of thyroid hormones.
  • Follicle-stimulating hormone is a glycoprotein hormone that targets the gonads and effects the growth of the reproductive system.
  • Luteinizing hormone is a glycoprotein hormone that targets the gonads to effect sex-hormone production.
  • Growth hormone is a polypeptide hormone that targets the liver and adipose tissue and promotes growth through lipid and carbohydrate metabolism.
  • Hormone secretion from the anterior pituitary gland is regulated by hormones secreted by the hypothalamus.

• Hormone Receptors

  • A hormone receptor is a molecule that binds to a specific hormone.
  • Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm.
  • The hormone activity within a target cell is dependent on the effective concentration of hormone-receptor complexes that are formed.
  • Many hormones are composed of polypeptides—such as thyroid-stimulating hormones, follicle-stimulating hormones, luteinizing hormones, and insulin.
  • Lipophilic hormones—such as steroid or thyroid hormones—are able to pass through the cell and nuclear membrane; therefore receptors for these hormones do not need to be, although they sometimes are, located in the cell membrane.

• Uterine (Menstrual) Cycle

  • The discharge of blood slows and then stops in response to rising hormone levels, and the lining of the uterus thickens, or proliferates, hence the name of the phase.
  • Ovulation is triggered by a surge in luteinizing hormone.
  • The sudden change in hormones at the time of ovulation sometimes causes minor changes in the endometrium and light mid-cycle blood flow.
  • These hormone drops cause the uterus to shed its lining and the egg in a process termed menstruation.

• Male and Female Gonads

  • Prior to ovulation, follicle-stimulating hormone is secreted by the granulosal cells that convert testosterone into estradiol.
  • The functions of the testicles are influenced by gonadotropic hormones, that are produced by the anterior pituitary.
  • Luteinizing hormone results in testosterone release.
  • The presence of both testosterone and follicle-stimulating hormone is needed to support spermatogenesis.

• Hormonal Methods

  • Hormonal birth control contains steroid hormones that alter female fertility.
  • Altogether, 18% of the world's contraceptive users rely on hormonal methods.
  • Hormonal contraception is highly effective: when taken on the prescribed schedule, users of steroid hormone methods experience pregnancy rates of less than 1% per year.
  • The effect of hormonal agents on the reproductive system is complex.
  • Progesterone negative feedback decreases the frequency of gonadotropin-releasing hormone (GnRH) released by the hypothalamus, which decreases the release of follicle-stimulating hormone (FSH), and greatly decreases the release of luteinizing hormone (LH) by the anterior pituitary.

• Puberty

  • It is initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy.
  • For boys, an androgen called testosterone is the principal sex hormone.
  • The hormone that dominates female development is an estrogen called estradiol.
  • Puberty, and sexual maturity thereafter, is regulated by a series of hormones and feedbacks in the body, illustrated here.
  • Hormones include: 1 Follicle-stimulating hormone - FSH. 2 Luteinizing hormone - LH. 3 Progesterone. 4 Estrogen. 5 Hypothalamus. 6 Pituitary gland. 7 Ovary. 8 Pregnancy - hCG (Human chorionic gonadotropin). 9 Testosterone. 10 Testicle. 11 Incentives. 12 Prolactin - PRL.