capillary

Examples of capillary in the following topics:

• Capillaries

  • Capillaries, the smallest blood vessels in the body, are part of the microcirculation.
  • Capillaries do not function independently.
  • The capillary bed is an interwoven network of capillaries that supplies an organ.
  • Sinusoidal - Sinusoidal capillaries are a special type of fenestrated capillaries that have larger openings (30-40 μm in diameter) in the endothelium.
  • Capillary beds may control blood flow via autoregulation.

• Capillary Dynamics

  • Hydrostatic and osmotic pressure are opposing factors that drive capillary dynamics.
  • Capillary exchange refers to the exchange of material between the blood and tissues in the capillaries.
  • Hydrostatic pressure is the force generated by the pressure of fluid within or outside of capillary on the capillary wall.
  • However, because large plasma proteins, especially albumin, cannot easily cross through the capillary walls, their effect on the osmotic pressure of the capillary interiors will to some extent balance the tendency for fluid to leak from the capillaries.
  • Describe hydrostatic pressure and osmotic pressure, the factors of capillary dynamics

• Lymphatic Capillaries

  • Lymphatic circulation begins in the smallest type of lymph vessels, the lymph capillaries.
  • Lymphatic capillaries are slightly larger in diameter than blood capillaries and contain flap-like "minivalves" that permit interstitial fluid to flow into them but not out, under normal conditions.
  • This opens the lymph capillaries more, increasing their volume and reducing their pressure to further facilitate fluid flow into the capillaries.
  • During inflammation, fluid leaks into the tissues at a rate faster than it can be removed by the lymph capillaries due to the increased permeability of cardiovascular capillaries.
  • The lymphatic capillaries bring lymph further into the lymphatic vessels.

• Arterioles

  • An arteriole is a small diameter blood vessel in the microcirculation system that branches out from an artery and leads to capillaries.
  • An arteriole is a small-diameter blood vessel which forms part of the microcirculation that extends from an artery and leads to capillaries.
  • The microcirculation involves the flow of blood in the smallest blood vessels, including arterioles, capillaries, and venules.
  • This reduces the pressure and velocity of blood flow to enable gas and nutrient exchange to occur within the capillaries.
  • Arterioles are part of the microcirculation system, along with capillaries, arteries, veins, venules, and tissue cells.

• 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.
  • This indicates that capillaries are normally in a state of filtration along their entire length.
  • Blood continues to flow around the nephron until it reaches another capillary-rich region the peritubular capillaries, where the previously filtered molecules are reabsorbed from the tubule of the nephron.

• Venules

  • Venules are small blood vessels in the microcirculation that connect capillary beds to veins.
  • A venule is a small blood vessel in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels called veins.
  • Venules range from 8 to 100μm in diameter and are formed when capillaries come together.
  • In contrast to regular venules, high-endothelial venules (HEV) are specialized post-capillary venous swellings.
  • Venules form when capillaries come together and converging venules form a vein.

• Movement of Fluid Among Compartments

  • It pushes water out of small tight junctions in the capillaries.
  • Because the blood in the capillaries is constantly flowing, equilibrium is never reached.
  • The balance between the two forces differs at different points on the capillaries.
  • If positive, fluid will tend to leave the capillary (filtration).
  • If negative, fluid will tend to enter the capillary (absorption).

• Sinusoid Development

  • The sinusoids are capillaries that develop after implantation to allow the exchange of gas and nutrients with the mother.
  • The portions of the veins above the upper ring become interrupted by the developing liver and broken up by it into a plexus of small, capillary-like vessels termed sinusoids.
  • A sinusoid is a small blood vessel that is a type of capillary similar to a fenestrated endothelium.
  • Sinusoids are actually classified as a type of open pore capillary (that is, discontinuous) as opposed to fenestrated.
  • Fenestrated capillaries have diaphragms that cover the pores, whereas open pore capillaries lack a diaphragm, having just an open pore.

• 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.
  • The force of hydrostatic pressure in the glomerulus (the force of pressure exerted from the pressure of the blood vessel itself) is the driving force that pushes filtrate out of the capillaries and into the slits in the nephron.

• Transcytosis

  • Transcytosis is a process by which molecules are transported into the capillaries.
  • Transcytosis, or vesicle transport, is one of three mechanisms that facilitate capillary exchange, along with diffusion and bulk flow.