peri-tubular capillaries

Examples of peri-tubular capillaries in the following topics:

• Tubular Reabsorption

  • Tubular reabsorption is the process by which solutes and water are removed from the tubular fluid and transported into the blood.
  • Reabsorbed fluids, ions, and molecules are returned to the bloodstream through the peri-tubular capillaries, and are not excreted as urine.
  • The mechanisms of reabsorption into the peri-tubular capillaries include:
  • These processes involve the substance passing though the luminal barrier and the basolateral membrane, two plasma membranes of the kidney epithelial cells, and into the peri-tubular capillaries on the other side.

• Bulk Flow: Filtration and Reabsorption

  • Bulk flow is used by small, lipid-insoluble solutes in water to cross the the capillary wall and is dependent on the physical characteristics of the capillary.
  • Continuous capillaries have a tight structure reducing bulk flow.
  • Fenestrated capillaries permit a larger amount of flow and discontinuous capillaries allow the largest amount of flow.
  • Proteins and other large molecules are filtered out of the oxygenated blood in the glomerulus and pass into Bowman's capsule and the tubular fluid contained within.
  • Tubular reabsorption is the process by which solutes and water are removed from the tubular fluid and transported into the blood.

• Tubular Secretion

  • Hydrogen, creatinine, and drugs are removed from the blood and into the collecting duct through the peritubular capillary network.
  • Tubular secretion is the transfer of materials from peritubular capillaries to the renal tubular lumen; it is the opposite process of reabsorption.
  • Passive diffusion—the movement of molecules from the peritubular capillaries to the intersitial fluid within the nephron.
  • The substances that are secreted into the tubular fluid for removal from the body include:
  • The tubular secretion of H+ and NH4+ from the blood into the tubular fluid is involved in blood pH regulation.

• Renal Clearance

  • Clearance is a function of glomerular filtration, secretion from the peritubular capillaries to the nephron, and reabsorption from the nephron back to the peritubular capillaries.
  • Renal clearance depends mainly on GFR, tubular absorption, and tubular secretion.
  • Increased tubular secretion will increase clearance, while decreased tubular secretion will decrease clearance.
  • Increased tubular reabsorption will decrease clearance, while increased tubular reabsorption will increase clearance.

• Glomerular Filtration

  • Glomerular filtration is the renal process whereby fluid in the blood is filtered across the capillaries of the glomerulus.
  • It describes the process of blood filtration in the kidney, in which fluid, ions, glucose, and waste products are removed from the glomerular capillaries.
  • Blood plasma enters the afferent arteriole and flows into the glomerulus, a cluster of intertwined capillaries.
  • These then leave the glomerulus through the efferent arteriole, which becomes capillaries meant for kidney–oxygen exchange and reabsorption before becoming venous circulation.
  • 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.

• Glomerular Diseases

  • The nephron is a tubular structure in the kidney that filters blood to form urine.
  • The glomerulus, a network (tuft) of capillaries, is located at the beginning of the nephron, and performs the first step of filtering blood.
  • The blood is filtered through the capillaries of the glomerulus into the Bowman's capsule.
  • Unlike most other capillary beds, the glomerulus drains into an efferent arteriole rather than a venule.
  • 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.

• Appendicitis

  • On the basis of experimental evidence, acute appendicitis seems to be the end result of a primary obstruction of the appendix lumen (the inside space of a tubular structure).
  • Peri appendicitis, inflammation of tissues around the appendix, is often found in conjunction with other abdominal pathology.

• Yolk Sac Development

  • After circulating through a wide-meshed capillary plexus, it is returned by the vitelline veins to the tubular heart of the embryo.

• Overview of Urine Formation

  • During secretion some substances±such as hydrogen ions, creatinine, and drugs—will be removed from the blood through the peritubular capillary network into the collecting duct.
  • The end product of all these processes is urine, which is essentially a collection of substances that has not been reabsorbed during glomerular filtration or tubular reabsorbtion.