Type three secretion system

(noun)

Type three secretion system (often written Type III secretion system and abbreviated TTSS or T3SS, also called Injectisome or Injectosome) is a protein appendage found in several Gram-negative bacteria. In pathogenic bacteria, the needle-like structure is used as a sensory probe to detect the presence of eukaryotic organisms and secrete proteins that help the bacteria infect them. The proteins are secreted directly from the bacterial cell into the eukaryotic cell, also known as "the host" cell.

Examples of Type three secretion system in the following topics:

  • Tubular Secretion

    • This secretion is caused mainly by active transport and passive diffusion.
    • Many pharmaceutical drugs are protein-bound molecules thatDiagram showing the basic physiologic mechanisms of the kidney and the three steps involved in urine formation. amely filtration, reabsorption, secretion, and excretion. are easily secreted, which is why urine testing can detect the exposure to many types of drugs.
    • pH regulation is primarily a respiratory system process, due to the exchange of carbon dioxide (a component of carbonic acid in blood), however tubular secretion assists in pH homeostasis as well.
    • Urine that is formed via the three processes of filtration, reabsorption, and secretion leaves the kidney through the ureter, and is stored in the bladder before being removed through the urethra.
    • Diagram showing the basic physiologic mechanisms of the kidney and the three steps involved in urine formation.

  • Type III and Type IV Secretion

    • Type III and IV secretion systems are utilized by pathogenic bacteria to transfer molecules from the bacterial cell to the host cell.
    • Another pathogen, Shigella, which utilizes type III secretion systems is able to successfully carry out its infection by evading the immune system.
    • The type IV secretion systems can either secrete or receive molecules.
    • The type IV secretion system utilizes a process similar to this.
    • An example of a pathogenic bacteria that utilizes the type IV secretion system is Helicobacter pylori.

  • Gastrointestinal Reflex Pathways

    • The digestive system has a complex system of food movement and the regulation of secretion regulation, which are vital for its proper function.
    • Movement and secretion are regulated by both long reflexes from the central nervous system (CNS), short reflexes from the enteric nervous system (ENS), and reflexes from gastrointestinal system (GI) peptides working in harmony with each other.
    • Control of the digestive system is also maintained by enteric nervous system (ENS), which can be thought of as a digestive brain that helps to regulate motility, secretion and growth.
    • In turn, this inhibits gastric motility and secretion of gastric acid (HCl).
    • The gastroileal reflex is a third type of gastrointestinal reflex.

  • Chemistry of Hormones

    • There are three classes of hormones: peptide hormones, lipid hormones, and monoamine hormones.
    • Peptide hormones consist of short chains of amino acids, such as vasopressin, that are secreted by the pituitary gland and regulate osmotic balance; or long chains, such as insulin, that are secreted by the pancreas, which regulates glucose metabolism.
    • Steroid hormones, which form the majority of lipid hormones, are derived from carbohydrates; for example, testosterone is produced primarily in the testes and plays a key role in development of the male reproductive system.
    • For example, the tryptophan-derived melatonin that is secreted by the pineal gland regulates sleep patterns.
    • Distinguish between the hydrophilic and lipophilic types of endocrine hormones based on their chemical structures

  • Overview of Urine Formation

    • Urine is a waste byproduct formed from excess water and metabolic waste molecules during the process of renal system filtration.
    • Urine formation occurs during three processes:
    • The next step is reabsorption, during which molecules and ions will be reabsorbed into the circulatory system.
    • In the collecting duct, secretion will occur before the fluid leaves the ureter in the form of urine.
    • This illustration demonstrates the normal kidney physiology, showing where some types of diuretics act, and what they do.

  • Group Translocation

    • Group translocation is a protein export or secretion pathway found in plants, bacteria, and archaea.
    • Systems for secreting proteins across the bacterial outer membrane may be quite complex.
    • These systems may be described as type I secretion, type II secretion, etc.
    • In Gram-negative bacteria the Tat translocase is composed of three essential membrane proteins: TatA, TatB, and TatC.
    • Recall the following types of transport systems: PEP group translocation and the TAT pathway

  • Mechanisms of Hormone Action

    • A hormone is a secreted chemical messenger that enables communication between cells and tissues throughout the body.
    • Hormones are secreted by the glands of the endocrine system and they serve to maintain homeostasis and to regulate numerous other systems and processes, including reproduction and development.
    • The glands of the endocrine system secrete hormones directly into the extracellular environment.
    • Cellular recipients of a particular hormonal signal may be one of several cell types that reside within a number of different tissues.
    • Different tissue types may also respond differently to the same hormonal signal.

  • Type IV (Delayed Cell-Mediated) Reactions

    • Type IV hypersensitivity reactions are cell-mediated and take 2 to 3 days to develop.
    • Type IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop.
    • Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response.
    • CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response.
    • Describe Type IV cell-mediated reactions and explain why they take two to three days to develop

  • Histology of the Pancreas

    • The pancreas serves digestive and endocrine functions, and it is composed of two types of tissue: islets of Langerhans and acini.
    • The pancreas is a glandular organ in the digestive system and endocrine system of vertebrates.
    • Under a microscope, stained sections of the pancreas reveal two different types of parenchymal tissue.
    • Acinar cells belong to the exocrine pancreas and secrete digestive enzymes into the gut via a system of ducts.
    • Four main cell types exist in the islets.

  • Histology of the Large Intestine

    • The large intestine, or large bowel, is the last part of the digestive system in vertebrate animals.
    • These three bands start at the base of the appendix and extend from the cecum to the rectum.
    • The crypts and intestinal villi are covered by epithelium that contains two types of cells: goblet cells that secrete mucus and enterocytes that secrete water and electrolytes.
    • This is in contrast to the stomach, where the chief cells secrete pepsinogen.
    • In the intestine, the digestive enzymes are not secreted by the cells of the intestine.