[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

Descriptive text is not available for this image

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