capsule

Examples of capsule in the following topics:

• Glycocalyx and Capsule

• Glycocalyx

  • The cell capsule is a very large structure of some bacterial cells.
  • Most capsules are difficult to stain using standard stains because most stains do not adhere to the capsule.
  • The capsule can protect cells from engulfment by eukaryotic cells, such as macrophages.
  • A capsule-specific antibody may be required for phagocytosis to occur.
  • Capsules also contain water which protects bacteria against desiccation.

• Nerve and Blood Supply

  • The articular capsule is highly innervated but avascular (lacking blood and lymph vessels), and receives nutrition from the surrounding blood supply via either the slow process of diffusion or convection, a far more efficient process.
  • Numerous vessels from this plexus pierce the fibrous capsule and form a rich vascular plexus in the deeper part of the synovial membrane.
  • It supplies the capsule, synovial membrane, and the epiphyses.
  • The synovial cartilage in the capsule acts somewhat like a sponge.

• Regulation of Glomerular Filtration Rate

  • GFR=Filtration Constant X (Hydrostatic Glomerulus Pressure–Hydrostatic Bowman's Capsule Pressure)–(Osmotic Glomerulus Pressure+Osmotic Bowman's Capsule Pressure)
  • Changes in either the hydrostatic or osmotic pressure in the glomerulus or Bowman's capsule will change GFR.
  • The Bowman's capsule space exerts hydrostatic pressure of its own that pushes against the glomerulus.
  • Increased Bowman's capsule hydrostatic pressure will decrease GFR, while decreased Bowman's capsule hydrostatic pressure will increase GFR.
  • An obstruction will increase the Bowman's capsule hydrostatic pressure and will consequently decrease GFR.

• Structure of Synovial Joints

  • It is distinguished by a surrounding synovial capsule.
  • The joint may be divided, completely or incompletely, by an articular disk or meniscus, the periphery of which is continuous with the fibrous capsule while its free surfaces are covered by synovial membrane.
  • The articular capsule is fibrous and continuous with the periosteum of articulating bones, surrounding the diarthrosis and uniting the articulating bones.
  • A synovial membrane (or synovium) is the soft tissue found between the articular capsule (joint capsule) and the joint cavity of synovial joints.
  • The main structural differences between synovial and fibrous joints are the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within those capsules (synovial cavities).

• Glomerular Diseases

  • Bowman's capsule surround the glomerulus.
  • The blood is filtered through the capillaries of the glomerulus into the Bowman's capsule.
  • The Bowman's capsule empties the filtrate into a tubule that is also part of the nephron.
  • This, in turn, aids the process of ultrafiltration, where fluids and soluble materials in the blood are forced out of the capillaries and into Bowman's capsule.
  • A glomerulus and its surrounding Bowman's capsule constitute a renal corpuscle, the basic filtration unit of the kidney.

• Internal Anatomy of the Kidneys

  • The renal cortex is a space between the medulla and the outer capsule.
  • The kidneys are surrounded by a renal cortex, a layer of tissue that is also covered by renal fascia (connective tissue) and the renal capsule.
  • At one end of each nephron, in the cortex of the kidney, is a cup-shaped structure called the Bowman's capsule.
  • It surrounds a tuft of capillaries called the glomerulus that carries blood from the renal arteries into the nephron, where plasma is filtered through the capsule.
  • After entering the capsule, the filtered fluid flows along the proximal convoluted tubule to the loop of Henle and then to the distal convoluted tubule and the collecting ducts, which flow into the ureter.

• Glomerular Filtration

  • The Bowman's capsule (also called the glomerular capsule) surrounds the glomerulus and is composed of visceral (simple squamous epithelial cells—inner) and parietal (simple squamous epithelial cells—outer) layers.
  • A diagram showing the afferent and efferent arterioles bringing blood in and out of the Bowman's capsule, a cup-like sac at the beginning of the tubular component of a nephron.

• Microbial Evasion of Phagocytosis

  • Bacteria often produce proteins or sugars that coat their cells and interfere with phagocytosis; these are called capsules.
  • Streptococcus pneumoniae produces several types of capsule which provide different levels of protection, and group A streptococci produce proteins such as M protein and fimbrial proteins to block engulfment.
  • Bacterial cells of Staphylococcus aureus: its large capsule protects the organism from attack by immunological defenses.

• Kidney Structure

  • The second layer, the perirenal fat capsule, helps anchor the kidneys in place.
  • The third and innermost layer is the renal capsule.
  • Externally, the kidney is surrounded by the renal fascia, the perirenal fat capsule, and the renal capsule.