| splanchnic layer | The internal layer of the lateral mesoderm, lying adjacent to the endoderm and together with it forming the splanchnopleure. (05 Mar 2000) |
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| splanchnic mesoderm | The layer of lateral plate mesoderm adjacent to the endoderm. (05 Mar 2000) |
| splanchnic nerve | <anatomy, nerve> One of the nerve's supplying the viscera. There are three groups of splanchnic nerves: cardiopulmonary splanchnic nerves, abdominopelvic nerves, and pelvic splanchnic nerves.the individual listings for the splanchnic nerves mentioned. (05 Mar 2000) |
| splanchnic nerves | The major nerves supplying sympathetic innervation to the abdomen. The greater, lesser, and lowest (or smallest) splanchnic nerves are formed by preganglionic fibres from the spinal cord which pass through the paravertebral ganglia and then to the coeliac ganglia and plexuses. The lumbar splanchnic nerves carry fibres which pass through the lumbar paravertebral ganglia to the mesenteric and hypogastric ganglia. (12 Dec 1998) |
| splanchnic wall | The wall of one of the viscera or the splanchnopleure from which it is formed. (05 Mar 2000) |
| thoracic splanchnic nerves | Splanchnic nerves arising from the thoracic portion of the sympathetic trunks; the upper thoracic splanchnic nerves (from T1 to T4 or 5) pass to viscera above the diaphragm (mainly heart and lungs) and so are cardiopulmonary splanchnic nerves; the lower thoracic splanchnic nerves form the greater, lesser, and lowest splanchnic nerves and supply viscera below the level of the diaphragm, and so are abdominopelvic splanchnic nerves. (05 Mar 2000) |
| upper thoracic splanchnic nerves | Part of the cardiopulmonary splanchnic nerves from the second to fifth segments of the thoracic sympathetic trunk that pass medially and anteriorly to enter the cardiac plexus; they convey postsynaptic sympathetic fibres to, and visceral afferent (pain) fibres from, the heart. Synonym: nervi cardiaci thoracici, upper thoracic splanchnic nerves. (05 Mar 2000) |
| lateral splanchnic arteries | Artery's that arise in the embryo from the dorsal aorta to supply the mesonephros, testis or ovary, and adrenal gland. (05 Mar 2000) |
| lesser splanchnic nerve | <anatomy, nerve> One of the abdominopelvic splanchnic nerves arising in the thorax from the last two thoracic sympathetic ganglia and passing through the diaphragm to the aorticorenal ganglion; conveys presynaptic sympathetic fibres and visceral afferent fibres. Synonym: nervus splanchnicus minor. (05 Mar 2000) |
| lowest splanchnic nerve | <anatomy, nerve> One of the abdominopelvic splanchnic nerves arising in the thorax and penetrating the diaphragm to supply presynaptic sympathetic fibres for the renal plexus; often combined with the lesser splanchnic nerve, but occasionally existing as an independent nerve. Synonym: nervus splanchnicus imus, smallest splanchnic nerve. (05 Mar 2000) |
| lumbar splanchnic nerves | Branches from the lumbar sympathetic trunks that pass anteriorly to convey presynaptic sympathetic fibres to, and visceral afferents from, the coeliac, intermesenteric, aortic, and superior hypogastric plexuses. Synonym: nervi splanchnici lumbales. (05 Mar 2000) |
| alveolocapillary block | The presence of material that impairs the diffusion of gases between the air in the alveolar spaces and the blood in alveolar capillaries; block can be caused by oedema, cellular infiltration, fibrosis, or tumour, and results in undersaturation of peripheral arterial blood with oxygen. (05 Mar 2000) |
| anterograde block | Conduction block of an impulse traveling anywhere in its ordinary direction, for example, from the sinoatrial node toward the ventricular myocardium. (05 Mar 2000) |
| arborization block | Intraventricular block supposedly due to widespread blockage in the Purkinje ramifications and manifested in the electrocardiogram by a pattern similar to bundle-branch block but with complexes of low amplitude. (05 Mar 2000) |
| atrioventricular block | <cardiology> A conduction disturbance that results in the inappropriate delay (or complete inability) of a electrical impulse, generated in the atria, to reach the ventricles (via the atrioventricular node). Clinical types are divided into first (nonserious), second and third degree (most serious). Some drugs may precipitate atrioventricular block (for example clonidine, methyldopa, verapamil). A permanent pacemaker may be required for a third degree (complete) heart block. (02 Jan 1998) |