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Related to sinus node: Sinus Node Dysfunction
the mass of specialized cardiac muscle fibers that normally acts as the "pacemaker" of the cardiac conduction system; it lies under the epicardium at the upper end of the sulcus terminalis.
See sinoatrial node.
a cluster of hundreds of cells located in the right atrial wall of the heart, near the opening of the superior vena cava. It comprises a knot of modified heart muscle that generates impulses that travel swiftly throughout the muscle fibers of both atria, causing them to contract. Specialized pacemaker cells in the node have an intrinsic rhythm that is independent of any stimulation by nerve impulses from the brain and the spinal cord. Slender fusiform cells making up the sinoatrial node are largely filled with sarcoplasm but contain a few striated fibrillae. The cells are irregularly grouped together and, at the edge of the node, merge with the atrial musculature. The sinoatrial node will normally "fire" at a rhythmic rate of 70-75 beats/min. If the node fails to generate an impulse, pacemaker function will shift to another excitable component of the cardiac conduction system, such as the atrioventricular node or Purkinje's fibers. Certain hormones and various autonomic impulses can affect the sinoatrial node and cause it to "fire" faster, such as during strenuous physical activity. During a lifetime of 70 years the node generates about 2 billion impulses. Surgical implantation of an artificial pacemaker is a common procedure for individuals suffering from a defective sinoatrial node. Also called Keith-Flack node, Keith's bundle, pacemaker, sinoatrial node, sinus pacemaker. Compare atrioventricular node, Purkinje's network.
sinus nodeSinoatrial node, see there, SA node.
node(nod) [L. nodus, knot]
1. A knot, knob, protuberance, or swelling.
2. A constricted region.
3. A small rounded organ or structure.
Aschoff nodeAtrioventricular node.
atrioventricular nodeAbbreviation: 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.Synonym: Aschoff node See: atrioventricular bundle; conduction system of the heart for illus
In osteoarthritis, bony enlargement of the proximal interphalangeal joints.
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.
Joint swelling seen in rheumatoid arthritis.
Heberden nodesSee: Heberden nodes
A vascular node that structurally resembles a lymph node, present in certain ungulates. Synonym: hemal gland
Hensen nodeSee: Hensen, Christian Andreas Victor
A small encapsulated lymphoid organ that filters lymph. Lymph nodes are found at junctions or branches along the lymphatics. They provide sites where immune responses can be generated through the interaction of antigens, macrophages, dendritic cells and lymphocytes. See: illustration; immune response; inflammation; lymph; lymphocyteLymph nodes are 0.1-2.5 cm long kidney-shaped aggregates of lymphocytes and macrophages embedded in a meshwork 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 nodesSee: Meynet nodes
neurofibril nodeRanvier's node.
Osler nodesSee: Osler nodes
Parrot nodesSee: Parrot nodes
A node on the hair shaft seen in piedra.
A knoblike structure at the anterior end of the primitive streak.Synonym: Hensen knot; primitive knot
Ranvier nodeSee: Ranvier 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.
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.
2. Signal node.
Enlargement of one of the supraclavicular lymph nodes; usually indicative of primary carcinoma of thoracic or abdominal organs. Synonym: sentinel node (2); Troisier's node; Virchow 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. Synonym: chorditis nodosa; laryngeal nodule
sinoatrial nodeAbbreviation: 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.Synonym: pacemaker (2); sinus node
sinus nodeSinoatrial 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's nodes
Troisier's nodeSignal node.
Virchow nodeSignal node.
1. a recess, cavity, or channel, as (a) one in bone or (b) a dilated, valveless channel for venous blood.
2. an abnormal channel or fistula, permitting escape of pus. In common, unqualified usage, the word sinus refers to any of the cavities in the skull that are connected with the nasal cavity—the paranasal sinuses.
furrows, with pouchlike recesses at their distal ends, separating the rectal columns; called also anal crypts.
a dural venous sinus which runs on the floor of the cranial cavity and out through the foramen magnum.
an irregularly shaped venous channel between the layers of dura mater of the brain, one on either side of the body of the sphenoid bone and communicating across the midline. Several cranial nerves and, when present, the rete mirabile, course through this sinus.
cavernous sinus syndrome
lesions of the cavernous syndrome, caused by neoplasia or infectious agents, result in a dilated pupil and paralysis of the globe; vision is usually spared.
one of the ventricles of the brain.
a temporary depression in the neck of the embryo containing the branchial arches.
the venous channel encircling the pituitary gland, formed by the two cavernous sinuses and the anterior and posterior intercavernous sinuses.
cavity of the conchal bone.
the terminal portion of the great cardiac vein, which lies in the cardiac sulcus between the left atrium and ventricle, and empties into the right atrium.
dermoid sinus, dermal sinus
see dermoid sinus.
dorsal sagittal sinus
a large dural venous sinus located within the falx cerebri.
dura mater venous sinus
large channels for venous blood forming an anastomosing system between the layers of the dura mater of the brain.
that paranasal sinus consisting of the ethmoidal cells collectively, and communicating with the nasal meatuses.
see malar abscess.
one of the paired paranasal sinuses in the frontal bone, each communicating with the middle meatus of the ipsilateral nasal cavity.
see sinus hair.
an air-filled recess in the head of birds which lies lateral to the nasal cavity into which it opens.
channels connecting the two cavernous sinuses, one passing anterior and the other posterior to the stalk of the pituitary gland.
the cutaneous pouch, which lies between the claws of sheep and some other ruminants and whose wall contains apocrine glands, and whose duct surfaces on the skin just above the coronets; it serves as a trail gland.
irregular, tortuous spaces within lymphoid tissues through which lymph flows.
one of the paired paranasal sinuses in the body of the maxilla on either side, opening into the middle meatus of the ipsilateral nasal cavity. In the horse it is divided into two compartments that communicate independently with the nasal chambers. All other sinuses of the horse communicate with the nasal chambers via the caudal maxillary sinus.
see paranasal sinuses (below).
a branch of the glossopharyngeal nerve; carries the afferent fibers of the stretch receptors in the wall of the carotid sinus.
see sinoatrial node.
a venous sinus between the layers of dura mater, passing along the midline of the cerebellum.
mucosa-lined air cavities in bones of the skull, communicating with the nasal cavity and including ethmoidal, frontal, maxillary and sphenoidal sinuses.
petrosal sinus (inferior)
a venous channel arising from the cavernous sinus and draining into the internal jugular vein.
petrosal sinus (superior)
one arising from the cavernous sinus and draining into the transverse sinus of the dura mater.
the dorsolateral recess between the seminal colliculus and the wall of the urethra.
pulmonary trunk sinus
spaces between the wall of the pulmonary trunk and cusps of the pulmonary valve at its opening from the right ventricle.
red pulp sinus
vascular storage in the spleen into which capillaries empty.
sinus reflex arc
afferent fibers are in the sinus nerve; these connect with the cardioinhibitory and vasomotor centers which control blood pressure and heart rate via sympathetic fibers to blood vessels; provides a route for the sinus reflex which relates pressure in the carotid sinus to the performance of the circulatory system.
a recess in the substance of the kidney, occupied by the renal pelvis, calices, vessels, nerves and fat.
sagittal sinus (inferior)
a small venous sinus of the dura mater of large animals found between the cerebral hemispheres and opening into the straight sinus.
sagittal sinus (superior)
a venous sinus of the dura mater that courses between the cerebral hemispheres and ends in the confluence of sinuses.
scleral venous sinus
see schlemm's canal.
a venous sinus of the dura mater on either side, continuous with the straight sinus and draining into the internal jugular vein of the same side.
one of the paired paranasal sinuses in the body of the sphenoid bone of some species. In the horse it communicates with the nasal cavity via the frontal and caudal maxillary sinuses.
one of the venous sinuses of the dura mater, emptying into the cavernous sinus.
dilated venous channels in the substance of the spleen. See also red pulp sinus (above).
a venous sinus of the dura mater formed by junction of the great cerebral vein and inferior sagittal sinus, and ending in the confluence of sinuses.
a space between the calcaneus and talus.
transverse dura mater sinus
a large venous sinus that runs in the attached border of the cerebellar tentorium on either side of the skull.
transverse pericardial sinus
a passage within the pericardial sac, between the aorta and pulmonary trunk cranioventrally, and the left atrium and cranial vena cava dorsally.
a deep recess on the medial wall of the middle ear.
an anomalous closure of the urachal canal in the newborn in which the opening at the umbilicus remains open. The bladder is normal. It is the cause of persistent infection and swelling at the umbilicus in the young animal and may lead to cystitis and pyelonephritis.
a small cavity in the glans penis of the horse, above the urethral process; as a recess of the fossa glandis it is usually filled with a small mass (bean) of inspissated smegma.
an elongated sac formed by division of the cloaca in the early embryo, which ultimately forms most of the vestibule, urethra and vagina in the female, and some of the urethra in the male.
venous channels in the wall of the uterus in pregnancy.
blood spaces between the placenta and uterine sinuses.
venae caval sinus
the posterior portion of the right atrium into which the inferior and the superior vena cava open.
a chamber which is the greater part of the right atrium into which the great veins discharge.
venous sinus, sinus venosus
1. the common venous receptacle in the heart of the early embryo that receives blood from the umbilical and vitelline veins and from the body via the ducts of Cuvier.
2. sinus of venae cavae.
a continuation of part of the common occipital vein in birds; it emerges from the foramen magnum and accompanies the vertebral vein.