secondary messenger

Examples of secondary messenger in the following topics:

• Direct Gene Activation and the Second-Messenger System

  • This signal is called the secondary messenger.
  • The secondary messenger may then activate a secondary effector, whose effects depend on the particular secondary messenger system.
  • The effector stimulates a second messenger synthesis. 4.
  • The second messenger activates an intercellular process.
  • Distinguish between the hormone mechanisms of direct gene activation and the second-messenger system

• Ionotropic and Metabotropic Receptors

  • Ionotropic receptors are a group of transmembrane ion channels that open or close in response to the binding of a chemical messenger (ligand) such as a neurotransmitter.The binding site of endogenous ligands on LGICs protein complexes are normally located on a different portion of the protein (an allosteric binding site) than the location of the ion conduction pore.The ion channel is regulated by a ligand and is usually very selective to one or more ions such as Na+, K+, Ca2+, or Cl-.
  • Metabotropic receptors are a subtype of membrane receptors that do not form an ion channel pore but use signal transduction mechanisms, often G proteins, to activate a series of intracellular events using second messenger chemicals.
  • When the neurotransmitter binds to the receptor, there is an activation via the G-protein that later activates the  secondary messengers.

• Hormone Receptors

  • Following an interaction with the hormones, a cascade of secondary effects within the cytoplasm of the cell is triggered, often involving the addition or removal of phosphate groups to cytoplasmic proteins, changes in ion channel permeability, or an increase in the concentrations of intracellular molecules that may act as secondary messengers, such as cyclic AMP.

• Overview of the Endocrine System

  • The endocrine system is a system of ductless glands that secrete hormones—chemical messengers that are carried for long distances.
  • The major endocrine glands include the pituitary, pineal, ovaries, testes, thyroid, hypothalamus and adrenal glands, additionally other tissues such as the kidney and liver also display secondary adrenal functions.

• Comparing the Nervous and Endocrine Systems

  • The nervous system and endocrine system both use chemical messengers to signal cells, but each has a different transmission speed.
  • The nervous system and the endocrine system use chemical messengers to signal cells, but the speed at which these messages are transmitted and the length of their effects differs.
  • The nervous system responds rapidly to stimuli by sending electrical action potentials along neurons, which in turn transmit these action potentials to their target cells using neurotransmitters, the chemical messenger of the nervous system.

• Mechanisms of Hormone Action

  • A hormone is a secreted chemical messenger that enables communication between cells and tissues throughout the body.
  • A hormone is a chemical messenger that enables communication between cells.
  • Water-soluble hormones, such as epinephrine, bind to a cell-surface localized receptor, initiating a signaling cascade using intracellular second messengers.

• Raynaud's Phenomenon

  • Raynaud's syndrome, or secondary Raynaud's, occurs secondary to a wide variety of other conditions.
  • Secondary Raynaud's has a number of associations such as connective tissue disorders, eating disorders such as anorexia nervosa, and obstructive disorders.
  • Drugs which may cause secondary Raynaud's include beta-blockers, chemotherapeutics, and anthrax vaccines.
  • A careful medical history will often reveal whether the condition is primary or secondary.
  • Once this has been established, an examination is largely to identify or exclude possible secondary causes.

• 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.
  • By around day 9 of the cycle, only one healthy secondary follicle remains, with the rest having been reabsorbed into the ovary.
  • This causes the secondary follicle to develop into a tertiary follicle, which then leaves the ovary 24–36 hours later.
  • 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.
  • Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II.

• Lymphoid Tissue

  • The lymphoid tissue may be primary or secondary depending upon its stage of lymphocyte development and maturation.
  • Secondary or peripheral lymphoid organs maintain mature naive lymphocytes until an adaptive immune response is initiated.
  • During antigen presentation, such as from the dendritic cells, lymphocytes migrate to germinal centers of the secondary lymphoid tissues, where they undergo clonal expansion and affinity maturation.
  • Secondary lymphoid tissue provides the environment for the antigens to interact with the lymphocytes.
  • The thymus and bone marrow are primary lymphoid tissue, while the lymph nodes, tonsils, and spleen are secondary lymphoid tissue.

• Syphilis

  • Secondary syphilis shows itself with a diffuse rash that frequently involves the palms of the hands and soles of the feet .
  • Secondary syphilis occurs approximately four to 10 weeks after the primary infection.
  • Approximately 30 to 60 percent of those exposed to primary or secondary syphilis will get the disease.
  • If adequate treatment is not administered, the infection progresses to the secondary stage.
  • Dermatologic manifestations are the hallmark of secondary syphilis.