Heuser's membrane

Examples of Heuser's membrane in the following topics:

• Development of the Extraembryonic Coelom

  • It is located between Heuser's membrane and the trophoblast.
  • The extra-embryonic coelom (or chorionic cavity) is a portion of the conceptus consisting of a cavity between Heuser's membrane and the trophoblast.
  • During the formation of the primitive yolk sac, some of the migrating hypoblast cells transdifferentiate into mesenchymal cells that fill the space between Heuser's membrane and the trophoblast to form the extra-embryonic mesoderm.
  • The extra-embryonic mesoderm is divided into two layers: the extra-embryonic splanchnopleuric mesoderm, which lies adjacent to Heuser's membrane around the outside of the primitive yolk sac; and the extra-embryonic somatopleuric mesoderm, which lies adjacent to the cytotrophoblast layer of the embryo.
  • The chorion is one of the membranes that exist during pregnancy between the developing fetus and the mother.

• Yolk Sac Development

  • In the meantime Heuser's membrane, located on the opposite pole of the developing vesicle, starts its upward proliferation and meets the hypoblast.
  • The yolk sac is a membranous sac attached to the embryo that provides nourishment in the form of yolk.

• Membrane Potentials as Signals

  • Membrane potential (also transmembrane potential or membrane voltage) is the difference in electrical potential between the interior and the exterior of a biological cell.
  • The membrane serves as both an insulator and a diffusion barrier to the movement of ions.
  • Ion transporter/pump proteins actively push ions across the membrane to establish concentration gradients across the membrane, and ion channels allow ions to move across the membrane down those concentration gradients, a process known as facilitated diffusion.
  • The membrane potential has two basic functions.
  • Signals are generated by opening or closing of ion channels at one point in the membrane, producing a local change in the membrane potential that causes electric current to flow rapidly to other points in the membrane.

• Epithelial Membranes

  • The mucous membranes are linings of ectodermal origin.
  • These mucus membranes are involved in absorption and secretion.  
  • These membranes exist in the  hollow organs of the digestive, respiratory, and urogenital tracts.
  • The term "mucous membrane" refers to where they are found in the body; not every mucous membrane secretes mucus.
  • Most mucous membranes contain stratified squamous or simple columnar epithelial tissue.

• Basement Membranes and Diseases

  • The basement membrane anchors epithelium to the connective tissue beneath it.
  • The two layers are collectively known as the basement membrane.
  • The basement membrane is also essential for angiogenesis (development of new blood vessels).
  • Basement membrane proteins have been found to accelerate differentiation of endothelial cells.
  • Some diseases result from a poorly-functioning basement membrane.

• Interosseous Membranes

  • The interosseous membrane is a type of connective tissue found between certain bones in the body.
  • The long bones of the lower arm and the leg both have attached interosseous membranes.
  • The muscles in the leg are separated into sections in the front and back with this membrane.
  • Twisting bones with an attached interosseous membrane in an abnormal or extreme position can damage the membrane, as well as create a fracture in one or both bones.
  • This image shows the interosseous membrane connecting the radius and the ulna.

• Resting Membrane Potentials

  • The potential difference in a resting neuron is called the resting membrane potential.
  • The potential difference in a resting neuron is called the resting membrane potential.
  • This causes the membrane to be polarized.
  • The value of the resting membrane potential varies from -40mV to -90mV in a different types of neurons.
  • The resting membrane potential exists only across the membrane.

• The Action Potential and Propagation

  • Action potential is a brief reversal of membrane potential where the membrane potential changes from -70mV to +30mV.
  • When the membrane potential of the axon hillock of a neuron reaches threshold, a rapid change in membrane potential occurs in the form of an action potential.
  • This moving change in membrane potential has three phases.
  • As additional sodium rushes in, the membrane potential actually reverses its polarity.  
  • As a result, the membrane permeability to sodium declines to resting levels.

• Serous Membranes

  • Serous membranes line and enclose serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement.
  • In anatomy, a serous membrane (or serosa) is a smooth membrane consisting of a thin layer of cells, which secrete serous fluid, and a thin connective tissue layer.
  • Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath.
  • Therefore, each organ becomes surrounded by serous membrane; they do not lie within the serous cavity.
  • Describe the function of the serous membranes in the pericardial, pleural, and peritoneal cavities

• Postsynaptic Potentials and Their Integration at the Synapse

  • Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse.
  • Many postsynaptic membrane receptors at chemical synapses are specialized to open ion channels.
  • At excitatory synapses, neurotransmitter binding depolarizes the postsynaptic membrane.
  • Unlike the action potential in axonal membranes, chemically-gated ion channels open on postsynaptic membranes.
  • EPSPs and IPSPs are transient changes in the membrane potential.