Atrioventricular node Health Dictionary

The term node is widely used in medicine. For instance, the smaller lymphatic glands are often termed LYMPH NODES. It is also applied to a collection of nerve cells forming a subsidiary nerve centre found in various places in the sympathetic nervous system (see NERVOUS SYSTEM), such as the sinuatrial node and the atrioventricular node which control the beating of the HEART.... node

This is the natural pacemaker of the HEART, and comprises a collection of specialised muscle cells in the wall of the upper chamber (atrium) of the heart. The cells initiate electrical impulses at a rate of up to 100 a minute. These impulses stimulate the muscles of the heart to contract. The rate is altered by the effects of certain hormones and various impulses from the nervous system. Damage or disease of the node affects the regular beating of the heart. (See also CARDIAC PACEMAKER.)... sinoatrial node

The central drainage and metabolic organs strung along the lymph vessels. The mesenchymal structure is native, being present at birth. The functional cells have all migrated there, some recently from the marrow, spleen, thymus or blood, others have resided since a few months after birth. Much of the antibody memory is stored in these nodes, and having only venous blood supply, lymph nodes are constantly shunting metabolized substances back into the blood, so the final lymph drainage from the thoracic duct into the left subclavian vein (or the right subclavian) contains fluid already screened and cleansed by many nodes.... lymph nodes

A small organ lying along the course of a lymphatic vessel (see lymphatic system); commonly but incorrectly called a lymph gland. Lymph nodes vary considerably in size, from microscopic to about 2.5 cm (1 in) in diameter.

A lymph node consists of a thin, fibrous outer capsule and an inner mass of lymphoid tissue. Penetrating the capsule are several small lymphatic vessels (whichcarry lymph into the node). Each node contains sinuses (spaces), in which the lymph is filtered. The flow of the lymph slows as it moves through narrow channels in the sinuses; this reduction in flow allows macrophages (white blood cells that engulf and destroy foreign and dead material) time to filter microorganisms from the lymph. Germinal centres in the lymph node release white blood cells called lymphocytes, which also help to fight infection. A single, larger vessel carries lymph out of the node.... lymph node

Small hard knobs which appear at the sides of the last phalanges of the ?ngers in people who have OSTEOARTHRITIS.... heberden’s nodes

Lymph nodes in the groin, next to the genitalia... inguinal nodes

See KAWASAKI DISEASE.... mucocutaneous lymph nodesyndrome

Small, greyish-white nodules that develop on the vocal cords as the result of constant voice strain.

In acute cases, treatment consists of resting the voice.

In chronic cases, surgical removal of the nodes may be necessary.... singer’s nodes

(AV bundle, bundle of His) a bundle of modified heart muscle fibres (Purkinje fibres) passing from the *atrioventricular node forward to the septum between the ventricles, where it divides into right and left bundles, one for each ventricle. The fibres transmit contraction waves from the atria, via the AV node, to the ventricles.... atrioventricular bundle

(AVNRT) *re-entry tachycardia arising from the presence of an abnormal electrical connection between atria and ventricles situated within the *atrioventricular node.... atrioventricular nodal re-entry tachycardia

(AVRT) *re-entry tachycardia arising from the presence of an abnormal electrical connection between atria and ventricles situated outside the *atrioventricular node. See accessory pathway.... atrioventricular reciprocating tachycardia

a bony thickening arising at the proximal interphalangeal joint of a finger in osteoarthritis. It is often found together with *Heberden’s nodes. [J. C. Bouchard (1837–1915), French physician]... bouchard’s node

a bony thickening arising at the terminal joint of a finger in *osteoarthritis. It is often inherited, with women most commonly affected. [W. Heberden (1710–1801), British physician]... heberden’s node

(primitive knot) the rounded front end of the embryonic *primitive streak. [V. Hensen (1835–1924), German pathologist]... hensen’s node

one of the gaps that occur at regular intervals in the *myelin sheath of medullated nerve fibres, between adjacent *Schwann cells.... node of ranvier

purplish nodes on the finger pulp or the *thenar or *hypothenar eminence. They are usually tender and a sign of bacterial *endocarditis. [Sir W. Osler]... osler’s nodes

protrusions of the pulpy inner material of an intervertebral disc into the vertebral body, generally found in the thoracic and lumbar spine. [C. G. Schmorl (1861–1932), German pathologist]... schmorl’s nodes

the first lymph node to show evidence of metastasis (spread) of a malignant tumour (e.g. breast cancer) via the lymphatic system. Absence of cancer cells in the sentinel node indicates that more distal lymph nodes will also be free of metastasis. In breast cancer, the change in practice to perform axillary lymph node dissection only if the sentinel node contains metastatic tumour has reduced the risk of arm lymphoedema. Similarly, in head and neck squamous cell carcinomas, the sentinel lymph node procedure is used as an alternative to neck dissection.... sentinel lymph node

an enlarged lymph node that may be palpated above the left clavicle (the left supraclavicular fossa). It is strongly associated with abdominal malignancy, particularly cancer of the stomach, since the lymphatic drainage from the abdomen is channelled via the thoracic duct to the left side of the neck before it enters the left subclavian vein. Enlargement of the right supraclavicular lymph node is associated with lung and oesophageal cancer.... virchow’s node