cytoplasm

Examples of cytoplasm in the following topics:

• Desmosomes

  • A desmosome is a type of cell junction that attaches to keratin in the cytoplasm and is a localized structure adjoining two cells.
  • A desmosome , also known as macula adherens, is a type of cell junction that attaches to filaments of keratin in the cytoplasm and is characterized by a localized patch that holds two cells tightly together.
  • On the cytoplasmic side of the plasma membrane, there are two dense structures called the Outer Dense Plaque (ODP) and the Inner Dense Plaque (IDP).
  • The Outer Dense Plaque is where the cytoplasmic domains of the cadherins attach to desmoplakin via plakoglobin and plakophillin.

• Hormone Receptors

  • 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.
  • Following interaction with the hormone 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 increased concentrations of intracellular molecules that may act as second messengers such as cyclic AMP.

• Gap Junctions

  • A gap junction is a specialized cell junction that directly connects the cytoplasm of two cells.
  • The cytoplasmic end of each connexon can also be closed, if necessary.

• Adherens Junctions

  • Adherens junctions provide strong mechanical attachments between adjacent cells through the linkage of cytoplasmic face with cytoskeleton.

• Mechanism and Contraction Events of Cardiac Muscle Fibers

  • In cardiac muscle, ECC is dependent on a phenomenon called calcium-induced calcium release (CICR), which involves the influx of calcium ions into the cell triggering further release of ions into the cytoplasm.
  • Calcium in the cytoplasm then binds to cardiac troponin-C, which moves the troponin complex away from the actin binding site.

• Microscopic Anatomy

  • Gap junctions, which connect proteins to the cytoplasm of different cells and transmit action potentials between both cells, and is required for cellular depolarization.

• Levels of Organization

  • Cells are made up of organic molecules, contain nucleic acids (such as DNA and RNA), are filled with fluid called cytoplasm, and have a membrane made out of lipids.
  • Cells also contain many structures within the cytoplasm called organelles, which perform various cellular functions.

• Platelet Formation

  • Megakaryocytes stay in the bone marrow and are thought to produce protoplatelets within their cytoplasm, which are released in cytoplasmic extensions upon cytokine stimulus.

• Antigenic Determinants and Processing Pathways

  • MHC molecules must move between the cell membrane and cytoplasm in order for antigen processing to occur properly.
  • The Endogenous Pathway- occurs when MHC class I molecules present antigens derived from intracellular (endogenous) proteins in the cytoplasm, such as the proteins produced within virally infected cells.
  • For example, cytomegalovirus and HIV infected cells can sometimes disrupt MHC movement through the cytoplasm, which may prevent them from binding to antigens or from moving back to the cell membrane after binding with an antigen.

• Spermatogenesis

  • Each cell division from a spermatogonium to a spermatid is incomplete; the cells remain connected to one another by bridges of cytoplasm to allow synchronous development.
  • Maturation then takes place under the influence of testosterone, which removes the remaining unnecessary cytoplasm and organelles.
  • The excess cytoplasm, known as residual bodies, is phagocytosed by surrounding Sertoli cells in the testes.