Taber's Medical Dictionary
node
(nōd)
[L. nodus, knot]
1. A knot, knob, protuberance, or swelling.
2. A constricted region.
3. A small rounded organ or structure.
atrioventricular node
ABBR: AV node A node of specialized cardiac muscle fibers in the lower interatrial septum that receives impulses from the sinoatrial node and transmits them to the bundle of His.
SYN: SEE: Tawara node
SEE: atrioventricular bundle; SEE: conduction system of the heart for illus
Bouchard node
SEE: Bouchard nodes
ectopic lymph node
A cluster of immunologically active cells inside a malignant tumor. The node may represent an attempt by the body to destroy foreign antigens on the tumor cell surface.
Heberden nodes
SEE: Heberden nodes
hemal node
A vascular node that structurally resembles a lymph node, present in certain ungulates.
lymph node
A small encapsulated lymphoid organ that filters lymph. Lymph nodes are found at junctions or branches along the lymphatic vessels. They are sites where immune responses can be generated through the interaction of antigens, macrophages, dendritic cells, and lymphocytes.
SYN: SEE: conglobate gland; SEE: lymph gland
LYMPH NODE ; SEE: immune response; SEE: inflammation; SEE: lymph; SEE: lymphocyte Lymph nodes are 0.1 to 2.5 cm long kidney-shaped aggregates of lymphocytes and macrophages embedded in a reticulum composed of thin collagen fibers. At each lymph node, an artery enters through a surface indentation (the hilum) alongside an exiting vein and an exiting (efferent) lymphatic vessel; a number of afferent lymphatic vessels enter the lymph node at other sites. Inside lymph nodes, lymph slowly flows through endothelial sinuses lined by lymphocytes and macrophages. Macrophages remove macromolecules, particles, debris, and microorganisms from the lymph stream. Lymphocytes and antibodies move through the walls of the sinuses and into the passing lymph, while dendritic cells pass from the lymph into the lymphatic follicles, carrying antigens from the body's epithelia and from infected tissues. In the cortical region of the lymph node, the sinuses wind around lymphatic follicles, which are ovoid germinal centers packed with differentiating and proliferating B lymphocytes and surrounded by loose T lymphocytes. Lymphocytes and antibodies also enter and exit blood capillaries throughout the lymph node. Lymph nodes are most numerous in the neck, mediastinum, abdominal mesenteries, pelvis, the proximal limbs (the axillae and the groin), and along the posterior abdominal wall. Inside the chest and trunk, lymph nodes tend to be found along the veins near viscera.
Meynet nodes
SEE: Meynet nodes
neurofibril node
SEE: Ranvier node.
Osler nodes
SEE: Osler nodes
Parrot nodes
SEE: Parrot nodes
piedric node
A node on the hair shaft seen in piedra.
primitive node
A knoblike structure at the anterior end of the primitive streak.
SYN: SEE: Hensen knot; SEE: primitive knot
Ranvier node
SEE: Ranvier node
Schmorl node
A node seen in radiographs of the spine. It is caused by prolapse of the nucleus pulposus into the end plate of the vertebra.
sentinel node
1. A lymph node that receives drainage from a tumor and is likely to harbor metastatic disease before cancer cells have the opportunity to spread elsewhere. SEE: 2. Signal node
signal node
Enlargement of one of the supraclavicular lymph nodes; usually indicative of primary carcinoma of thoracic or abdominal organs.
SYN: SEE: sentinel node
singer's node
Noncancerous, callus-like growths on the inner parts of the vocal cords, usually caused by voice abuse or overuse. It is marked by a singer's hoarseness and an inability to produce the desired notes. It is treated by resting the voice. Surgical removal of the nodules is necessary if they do not respond to conservative therapy.
SYN: SEE: chorditis nodosa; SEE: laryngeal nodule
sinoatrial node
ABBR: SA node A specialized group of cardiac muscle cells in the wall of the right atrium at the entrance of the superior vena cava. These cells depolarize spontaneously and rhythmically to initiate normal heartbeats.
SYN: SEE: pacemaker; SEE: sinus node
sinus node
SEE: Sinoatrial node.
syphilitic node
Circumscribed swelling at the end of long bones due to congenital syphilis. The nodes are sensitive and painful during inflammation, esp. at night.
SEE: Parrot nodes
