| 释义 |
DictionarySeecirculationEncyclopediaSeeCirculationMedicalSeeFETAL CIRCULATION: Vessels that carry oxygenated blood are redfetal circulationThe course of the flow of blood in a fetus. Oxygenated in the placenta, blood passes through the umbilical vein and ductus venosus to the inferior vena cava and thence to the right atrium. It then follows one of two courses: through the foramen ovale to the left atrium and thence through the aorta to the tissues, or through the right ventricle, pulmonary artery, and ductus arteriosus to the aorta and thence to the tissues. In either case the blood bypasses the lungs, which do not function before birth. Blood returns to the placenta through the umbilical arteries, which are continuations of the hypogastric arteries. At birth or shortly after, the ductus arteriosus and the foramen ovale close, establishing the postpartum circulation. If either fails to close, the baby may be hypoxemic. See: illustration; patent ductus arteriosusillustrationhypophyseal circulationSuperior and inferior hypophyseal arteries (slender branches from arteries of the circle of Willis) that provide blood to the pituitary gland and adjacent regions of the hypothalamus. Venous blood from the pituitary gland drains into the cavernous sinuses and, from there, into the internal jugular veins. Some of the superior hypophyseal arteries form primary capillary beds in the hypothalamus and the veins draining those beds ramify again to form secondary capillary beds in the adenohypophysis (anterior lobe of the pituitary), thus forming a portal circulation (the hypothalamic-pituitary portal circulation). Releasing factors secreted from the hypothalamus into the primary capillary beds reach the adenohypophysis via the secondary capillary beds. lymph circulationThe flow of lymph from the tissues into the lymphatic collecting system. Lymph is formed from the tissue fluid that fills the interstitial spaces of the body. It is collected into lymph capillaries, which carry the lymph to the larger lymph vessels. These converge to form one of two main trunks, the right lymphatic duct and the thoracic duct. The right lymphatic duct drains the right side of the head, neck, and trunk and the right upper extremity; the thoracic duct drains the rest of the body. The thoracic duct originates at the cisterna chyli, which receives the lymphatics from the abdominal organs and legs. It courses upward through the diaphragm and thorax and empties into the left subclavian vein near its junction with the left interior jugular vein. The right lymphatic duct empties into the right subclavian vein. Along the course of lymph vessels are lymph nodes, which remove bacteria and other foreign materials, thus preventing their entrance into the bloodstream. Lymph flow is maintained by a difference in pressure at the two ends of the system. Important accessory factors aiding lymph flow are breathing movements and muscular activity. persistent fetal circulation Abbreviation: PFC
A condition of newborns in which unoxygenated blood is shunted from the right to the left side of the heart through the ductus arteriosus and the foramen ovale, resulting in hypoxemia. It is caused by pulmonary hypertension and occurs most frequently in small-for-gestational-age infants and infants of diabetic mothers.  HEPATIC PORTAL CIRCULATIONportal circulation1. Blood flow from the abdominal organs that passes through the portal vein, the sinusoids of the liver, and into the hepatic vein before returning to the heart from the inferior vena cava. This pathway permits the liver to process and to detoxify substances entering the body from the gastrointestinal tract. 2. A portal system between the hypothalamus and the anterior pituitary gland. The hypothalamus secretes releasing or inhibiting hormones into the blood; they are carried directly to the anterior pituitary and stimulate or inhibit secretion of specific hormones. See: Hepatic Portal Circulation illustrationpulmonic circulationAn obsolete term for the pulmonary circulation.  PULMONARY CIRCULATIONpulmonary circulationThe flow of blood from the right ventricle of the heart to the lungs for exchange of oxygen and carbon dioxide in the pulmonary capillaries, then through the pulmonary veins to the left atrium. See: illustration SYSTEMIC CIRCULATIONsystemic circulationThe blood flow from the left ventricle through the aorta and all its arteries to the capillaries of the tissues and its return to the heart through veins and the venae cavae, which empty into the right atrium. See: illustrationvenous circulationCirculation via the veins.vitelline circulationThe embryonic circulation of blood to the yolk sac via the vitelline arteries and its return to general circulation through the vitelline veins.illustrationcirculation Movement in a circle or around a circuit, especially the movement of the blood through the arteries, capillaries and veins, as a result of the pumping action of the heart.cir·cu·la·tion (sĭr'kyū-lā'shŭn) Movements in a circle, or through a circular course, or through a course that leads back to the same point. [L. circulatio]">circulation red" href="javascript:eml2('davisTab', 'c405p0.jpg')"> FETAL CIRCULATION: Vessels that carry oxygenated blood are redfetal circulationThe course of the flow of blood in a fetus. Oxygenated in the placenta, blood passes through the umbilical vein and ductus venosus to the inferior vena cava and thence to the right atrium. It then follows one of two courses: through the foramen ovale to the left atrium and thence through the aorta to the tissues, or through the right ventricle, pulmonary artery, and ductus arteriosus to the aorta and thence to the tissues. In either case the blood bypasses the lungs, which do not function before birth. Blood returns to the placenta through the umbilical arteries, which are continuations of the hypogastric arteries. At birth or shortly after, the ductus arteriosus and the foramen ovale close, establishing the postpartum circulation. If either fails to close, the baby may be hypoxemic. See: illustration; patent ductus arteriosusillustrationhypophyseal circulationSuperior and inferior hypophyseal arteries (slender branches from arteries of the circle of Willis) that provide blood to the pituitary gland and adjacent regions of the hypothalamus. Venous blood from the pituitary gland drains into the cavernous sinuses and, from there, into the internal jugular veins. Some of the superior hypophyseal arteries form primary capillary beds in the hypothalamus and the veins draining those beds ramify again to form secondary capillary beds in the adenohypophysis (anterior lobe of the pituitary), thus forming a portal circulation (the hypothalamic-pituitary portal circulation). Releasing factors secreted from the hypothalamus into the primary capillary beds reach the adenohypophysis via the secondary capillary beds. lymph circulationThe flow of lymph from the tissues into the lymphatic collecting system. Lymph is formed from the tissue fluid that fills the interstitial spaces of the body. It is collected into lymph capillaries, which carry the lymph to the larger lymph vessels. These converge to form one of two main trunks, the right lymphatic duct and the thoracic duct. The right lymphatic duct drains the right side of the head, neck, and trunk and the right upper extremity; the thoracic duct drains the rest of the body. The thoracic duct originates at the cisterna chyli, which receives the lymphatics from the abdominal organs and legs. It courses upward through the diaphragm and thorax and empties into the left subclavian vein near its junction with the left interior jugular vein. The right lymphatic duct empties into the right subclavian vein. Along the course of lymph vessels are lymph nodes, which remove bacteria and other foreign materials, thus preventing their entrance into the bloodstream. Lymph flow is maintained by a difference in pressure at the two ends of the system. Important accessory factors aiding lymph flow are breathing movements and muscular activity. persistent fetal circulation Abbreviation: PFC
A condition of newborns in which unoxygenated blood is shunted from the right to the left side of the heart through the ductus arteriosus and the foramen ovale, resulting in hypoxemia. It is caused by pulmonary hypertension and occurs most frequently in small-for-gestational-age infants and infants of diabetic mothers. HEPATIC PORTAL CIRCULATIONportal circulation1. Blood flow from the abdominal organs that passes through the portal vein, the sinusoids of the liver, and into the hepatic vein before returning to the heart from the inferior vena cava. This pathway permits the liver to process and to detoxify substances entering the body from the gastrointestinal tract. 2. A portal system between the hypothalamus and the anterior pituitary gland. The hypothalamus secretes releasing or inhibiting hormones into the blood; they are carried directly to the anterior pituitary and stimulate or inhibit secretion of specific hormones. See: Hepatic Portal Circulation illustrationpulmonic circulationAn obsolete term for the pulmonary circulation. PULMONARY CIRCULATIONpulmonary circulationThe flow of blood from the right ventricle of the heart to the lungs for exchange of oxygen and carbon dioxide in the pulmonary capillaries, then through the pulmonary veins to the left atrium. See: illustrationSYSTEMIC CIRCULATIONsystemic circulationThe blood flow from the left ventricle through the aorta and all its arteries to the capillaries of the tissues and its return to the heart through veins and the venae cavae, which empty into the right atrium. See: illustrationvenous circulationCirculation via the veins.vitelline circulationThe embryonic circulation of blood to the yolk sac via the vitelline arteries and its return to general circulation through the vitelline veins.illustrationcirculation Movement in a circle or around a circuit, especially the movement of the blood through the arteries, capillaries and veins, as a result of the pumping action of the heart.cir·cu·la·tion (sĭr'kyū-lā'shŭn) Movements in a circle, or through a circular course, or through a course that leads back to the same point. [L. circulatio] |