extracellular matrix

Examples of extracellular matrix in the following topics:

• Extracellular Matrix of Animal Cells

  • The extracellular matrix of animal cells holds cells together to form a tissue and allow tissues to communicate with each other.
  • Collectively, these materials are called the extracellular matrix .
  • Not only does the extracellular matrix hold the cells together to form a tissue, but it also allows the cells within the tissue to communicate with each other.
  • An example of the role of the extracellular matrix in cell communication can be seen in blood clotting.
  • The extracellular matrix consists of a network of proteins and carbohydrates.

• Cell Signaling and Cell Death

  • For example, most normal animal cells have receptors that interact with the extracellular matrix, a network of glycoproteins that provides structural support for cells in an organism.
  • The binding of cellular receptors to the extracellular matrix initiates a signaling cascade within the cell.
  • However, if the cell moves away from the extracellular matrix, the signaling ceases, and the cell undergoes apoptosis.

• Programmed Cell Death

  • For example, most normal animal cells have receptors that interact with the extracellular matrix, a network of glycoproteins that provides structural support for cells in an organism.
  • The binding of cellular receptors to the extracellular matrix initiates a signaling cascade within the cell.
  • However, if the cell moves away from the extracellular matrix, the signaling ceases, and the cell undergoes apoptosis.

• Exocytosis

  • Exocytosis is the process by which cells release particles from within the cell into the extracellular space.
  • Exocytosis' main purpose is to expel material from the cell into the extracellular fluid; this is the opposite of what occurs in endocytosis.
  • This fusion opens the membranous envelope on the exterior of the cell and the waste material is expelled into the extracellular space .
  • Some examples of cells releasing molecules via exocytosis include the secretion of proteins of the extracellular matrix and secretion of neurotransmitters into the synaptic cleft by synaptic vesicles.

• Fertilization

  • In mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida.
  • In placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane .
  • (b) Acrosomal reactions help the sperm degrade the glycoprotein matrix protecting the egg and allow the sperm to transfer its nucleus.

• Complex Tissue Structure

  • As multicellular organisms, animals differ from plants and fungi because their cells don't have cell walls; their cells may be embedded in an extracellular matrix (such as bone, skin, or connective tissue); and their cells have unique structures for intercellular communication (such as gap junctions).
  • This connective tissue constitutes the extracellular surroundings of cells and is made up of organic and inorganic materials.

• Bone Development

  • Osteoblasts secrete the extracellular matrix and deposit calcium, which hardens the matrix.
  • Connective tissue in the matrix differentiates into red bone marrow in the fetus.
  • Responding to complex developmental signals, the matrix begins to calcify.
  • This calcification prevents diffusion of nutrients into the matrix, resulting in chondrocytes dying and the opening up of cavities in the diaphysis cartilage.
  • Blood vessels invade the cavities, while osteoblasts and osteoclasts modify the calcified cartilage matrix into spongy bone.

• Components of Plasma Membranes

  • The plasma membrane also plays a role in anchoring the cytoskeleton to provide shape to the cell, and in attaching to the extracellular matrix and other cells to help group cells together to form tissues.
  • These proteins can be receptors, which work as receivers of extracellular inputs and as activators of intracellular processes, or markers, which allow cells to recognize each other.
  • Membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors, which then trigger intracellular responses.

• Selective Permeability

  • There are peripheral proteins on the exterior of the membrane that bind elements of the extracellular matrix.
  • These carbohydrate complexes help the cell bind substances that the cell needs in the extracellular fluid.

• Intercellular Junctions

  • The extracellular matrix allows cellular communication within tissues through conformational changes that induce chemical signals, which ultimately transform activities within the cell.
  • For example, the tight junctions of the epithelial cells lining your urinary bladder prevent urine from leaking out into the extracellular space.