venous system

(noun)

The portion of the circulatory system composed of veins, which carry blood towards the heart.

Related Terms

Examples of venous system in the following topics:

  • Artery Function

    • The pressure in the arterial system decreases steadily, highest in the aorta and lowest in the venous system, as blood approaches the heart after delivery of oxygen to tissues in the systemic circulation.
    • Arteries of the systemic circulation can be subdivided into muscular or elastic types according to the the relative compositions of elastic and muscle tissue in their tunica media.
    • Distinguish the function of the arterial system from that of venous system

  • Venous Blood Pressure

    • Blood pressure generally refers to the arterial pressure in the systemic circulation.
    • However, measurement of pressures in the human venous system and the pulmonary vessels play an important role in intensive care medicine and are physiologically important in ensuring proper return of blood to the heart, maintaining flow in the closed circulatory system.
    • Variants of venous pressure include:
    • Jugular venous pressure (JVP), the indirectly observed pressure over the venous system.
    • TPR is primarily a function of the resistance of the systemic circulation.

  • Development of the Heart

    • The human arterial and venous systems develop from different embryonic areas.
    • While the arterial system develops mainly from the aortic arches, the venous system arises from three bilateral veins during weeks four through eight of human development.
    • The human arterial system originates from the aortic arches and from the dorsal aortae starting from week four of human development.
    • The definitive formation of the arterial system arise from aortic arches 3, 4 and 6.
    • The human venous system develops mainly from the vitelline veins, the umbilical veins and the cardinal veins, all of which empty into the sinus venosus.

  • Development of the Cardiovascular System

    • The circulatory system develops initially via vasculogenesis, with the arterial and venous systems developing from distinct embryonic areas.
    • The human arterial system originates from the aortic arches and from the dorsal aortae starting from week 4 of embryonic life.
    • The human arterial and venous systems develop from different embryonic areas.
    • The human venous system develops mainly from the vitelline,umbilical, and cardinal veins, all of which empty into the sinus venosus.
    • The venous system arises during the fourth to eighth weeks of human development.

  • Venules

    • In contrast to regular venules, high-endothelial venules (HEV) are specialized post-capillary venous swellings.

  • Cerebrospinal Fluid and Its Circulation

    • CSF is reabsorbed into venous sinus blood via arachnoid granulations.
    • This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF.
    • Chemical stability: CSF flows throughout the inner ventricular system in the brain and is absorbed back into the bloodstream, rinsing the metabolic waste from the central nervous system (CNS) through the blood-brain barrier.
    • The venous system is also important in this equation.
    • Describe the role and circulation of cerebrospinal fluid in the nervous system

  • Veins

    • In systemic circulation, oxygenated blood is pumped by the left ventricle through the arteries to the muscles and organs of the body, where its nutrients and gases are exchanged at capillaries.
    • Standing or sitting for prolonged periods can cause low venous return from venous pooling.
    • Veins are classified in a number of ways, including superficial vs. deep, pulmonary vs. systemic, and large vs. small:
    • Systemic veins - Systemic veins drain the tissues of the body and deliver deoxygenated blood to the heart.
    • Venous valves prevent back flow and ensure that blood flows in one direction.

  • Blood Supply to the Liver

    • In the hepatic portal system, the liver receives a dual blood supply from the hepatic portal vein and hepatic arteries.
    • In the hepatic portal system, the liver receives a dual blood supply from the hepatic portal vein and hepatic arteries.
    • Supplying approximately 75% of the liver's blood supply, the hepatic portal vein carries venous blood drained from the spleen, gastrointestinal tract and its associated organs .
    • A portal system is a venous structure that enables blood from one set of capillary beds to drain into another set of capillary beds, without first returning this blood to the heart.
    • The majority of capillaries in the body drain directly into the heart, making portal systems unusual.

  • Veins of the Head and Neck

    • In the head and neck, blood circulates from the upper systemic loop, which originates at the aortic arch.
    • Two main jugular veins are responsible for the venous draining of the head and neck.
    • The deep-lying internal jugular vein receives blood from the dural venous sinuses in the brain as well as the cerebral and cerebellar veins.

  • Chambers of the Heart

    • The left side of the heart deals with systemic circulation while the right side of the heart deals with pulmonary circulation.
    • One of the defining characteristics of the atria is that they do not impede venous flow into the heart.
    • Atria have four essential characteristics that cause them to promote continuous venous flow:
    • The venous blood entering the heart has a very low pressure compared to arterial blood, and valves would require venous blood pressure to build up over a long period of time to enter the atria.
    • The atrial contractions are slight, preventing significant back pressure that would impede venous flow.