lumen

Examples of lumen in the following topics:

• Epithelial Tissues

  • Epithelial tissues cover the outer surfaces of the body and the lumen of internal organs; they are classified by shape and number of layers.
  • They also line the lumens of organs in a single layer or multiple layers of cells.
  • These cells absorb material from the lumen of the digestive tract and prepare it for entry into the body through the circulatory and lymphatic systems.
  • Goblet cells secret mucous into the digestive tract lumen.

• The Endoplasmic Reticulum

  • The hollow portion of the ER tubules is called the lumen or cisternal space.
  • Ribosomes transfer their newly synthesized proteins into the lumen of the RER where they undergo structural modifications, such as folding or the acquisition of side chains.

• Processes of the Light-Dependent Reactions

  • In non-cyclic photophosphorylation, cytochrome b6f uses the energy of electrons from PSII to pump hydrogen ions from the lumen (an area of high concentration) to the stroma (an area of low concentration).
  • The electron transport chain moves protons across the thylakoid membrane into the lumen.
  • At the same time, splitting of water adds protons to the lumen while reduction of NADPH removes protons from the stroma.
  • The net result is a low pH in the thylakoid lumen and a high pH in the stroma.

• The Golgi Apparatus

  • The transport vesicles that formed from the ER travel to the cis face, fuse with it, and empty their contents into the lumen of the Golgi apparatus.

• Gametogenesis (Spermatogenesis and Oogenesis)

  • Spermatogenesis occurs in the wall of the seminiferous tubules , with stem cells at the periphery of the tube and the spermatozoa at the lumen of the tube.
  • When it reaches the lumen of the tubule and grows a flagellum (or "tail"), it is called a sperm cell.

• Main Structures and Summary of Photosynthesis

  • The thylakoid membrane encloses an internal space called the thylakoid lumen.

• Digestive System: Mouth and Stomach

  • Another cell type, parietal cells, secrete hydrogen and chloride ions, which combine in the lumen to form hydrochloric acid, the primary acidic component of the stomach juices.

• Male Reproductive Anatomy

  • The walls of the seminiferous tubules are composed of the developing sperm cells, with the least-developed sperm at the periphery of the tubule and the fully-developed sperm in the lumen.

• Regulating Immune Tolerance

  • IgA and other antibodies are secreted into the intestinal lumen.