luteinizing hormone

Examples of luteinizing hormone in the following topics:

• Male Hormones

  • The onset of puberty is controlled by two major hormones: FSH initiates spermatogenesis and LH signals the release of testosterone.
  • These changes are largely influenced by hormonal activity.
  • Hormones play an organizational role, priming the body to behave in a certain way once puberty begins, and an activational role, referring to changes in hormones during adolescence that trigger behavioral and physical changes.
  • At the onset of puberty, the hypothalamus begins secreting high pulses of GnRH, or gonadotropin-releasing hormone.
  • In response, the pituitary gland releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) into the male system for the first time.

• Hypothalamic-Pituitary Axis

  • The anterior pituitary produces seven hormones: growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), melanin-stimulating hormone (MSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH).
  • Anterior pituitary hormones are sometimes referred to as tropic hormones because they control the functioning of other organs.
  • While these hormones are produced by the anterior pituitary, their production is controlled by regulatory hormones produced by the hypothalamus.
  • These regulatory hormones can be releasing hormones or inhibiting hormones, causing more or less of the anterior pituitary hormones to be secreted.
  • Negative feedback then regulates how much of these regulatory hormones are released and how much anterior pituitary hormone is secreted.

• Hormonal Regulation of the Reproductive System

  • During puberty, in both males and females, the hypothalamus produces gonadotropin-releasing hormone (GnRH), which stimulates the production and release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary gland.
  • FSH production is inhibited by the hormone inhibin, which is released by the testes.
  • It is also called interstitial-cell-stimulating hormone.
  • Prolactin levels are regulated by the hypothalamic hormones, prolactin-releasing hormone (PRH) and prolactin-inhibiting hormone (PIH) (which is now known to be dopamine).
  • Hormonal regulation of the female reproductive system involves hormones from the hypothalamus, pituitary, and ovaries.

• Female Hormones

  • The stages of the ovarian cycle in the female are regulated by hormones secreted by the hypothalamus, pituitary, and the ovaries.
  • As with the male, the hypothalamic hormone GnRH (gonadotropin-releasing hormone) causes the release of the hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) from the anterior pituitary.
  • Follicle cells produce the hormone inhibin, which inhibits FSH production.
  • Estradiol and progesterone are steroid hormones that prepare the body for pregnancy.
  • Rising and falling hormone levels result in progression of the ovarian and menstrual cycles.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • All hormones in the human body can be divided into lipid-derived, amino acid-derived, and peptide hormones.
  • One of the key, distinguishing features of lipid-derived hormones is that they can diffuse across plasma membranes whereas the amino acid-derived and peptide hormones cannot.
  • The primary class of lipid hormones in humans is the steroid hormones.
  • Examples of steroid hormones include estradiol, which is an estrogen, or female sex hormone, and testosterone, which is an androgen, or male sex hormone.
  • The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone are shown.

• Humoral, Hormonal, and Neural Stimuli

  • The release of hormones can be triggered by changes in the blood ("humor"), by the actions of other hormones, or by neurological stimuli.
  • Hormonal stimuli refers to the release of a hormone in response to another hormone.
  • A number of endocrine glands release hormones when stimulated by hormones released by other endocrine glands.
  • The anterior pituitary, in turn, releases hormones that regulate hormone production by other endocrine glands.
  • The hypothalamus stimulates the anterior pituitary gland, via hormones, to release thyroid-stimulating hormone (TSH).

• How Hormones Work

  • Hormones are chemical messengers that relay messages to cells that display specific receptors for each hormone and respond to the signal.
  • All multicellular organisms produce hormones; plant hormones are also called phytohormones.
  • Hormones mediate changes in target cells by binding to specific hormone receptors.
  • Cells can have many receptors for the same hormone, but often also possess receptors for different types of hormones.
  • Cells respond to a hormone when they express a specific receptor for that hormone.

• Plasma Membrane Hormone Receptors

  • Amino acid-derived hormones and polypeptide hormones are not lipid-derived (lipid-soluble or fat-soluble); therefore, they cannot diffuse through the plasma membrane of cells.
  • Lipid-insoluble hormones bind to receptors on the outer surface of the plasma membrane, via plasma membrane hormone receptors.
  • Unlike steroid hormones, lipid-insoluble hormones do not directly affect the target cell because they cannot enter the cell and act directly on DNA.
  • The effect of a hormone is amplified as the signaling pathway progresses.
  • Describe the events that occur when a hormone binds to a plasma hormone receptor

• Hormone Functions

  • The endocrine system plays a role in growth, metabolism, and other processes by releasing hormones into the blood.
  • An animal's endocrine system controls body processes through the production, secretion, and regulation of hormones.
  • Target cells, those having a receptor for a signal, respond to a hormone when they express a specific receptor for that hormone.
  • Different tissue types may also respond differently to the same hormonal signal.
  • By releasing hormones, the endocrine system plays a role in growth, metabolism, and sexual development.

• Hormonal Responses to Food

  • The system is made of a series of glands that produce chemicals called hormones.
  • One of the important factors under hormonal control is the stomach acid environment.
  • Secretin acts in tandem with another hormone called cholecystokinin (CCK).
  • Another level of hormonal control occurs in response to the composition of food.
  • Scientists are exploring the role of each hormone in the digestive process and developing ways to target these hormones.