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(nok-tŭr′năl) [L. nocturnus, belonging to the night, at night] Pert. to or occurring in the night. SEE: diurnal. See words beginning with nyct-.

nocturnal eating (drinking) syndrome

A rare disorder involving frequent awakenings from sleep to eat or drink. Those affected are unable to return to sleep without eating a meal. The condition is most commonly observed in infants, young children, and people being treated with some sedatives. In adults it is considered to be both a sleep disorder and a binge eating disorder.

nocturnal penile tumescence

ABBR: NPT. Erection occurring during sleep. In the normal male, erections during sleep begin in early childhood and continue to at least the eighth decade. The total time of NPT averages 100 minutes per night. In evaluating erectile dysfunction (ED), the presence of NPT suggests the patient has psychogenic ED rather than neurogenic or vascular ED.


Nucleotide-binding oligomerization domain proteins.


(nōd′ăl) [L. nodus, knot] Pert. to a node or a protuberance.


(nŏd′ĭng) Involuntary motion of the head downward, as when momentarily dozing.


(nōd) [L. nodus, knot] 1. A knot, knob, protuberance, or swelling. 2. A constricted region. 3. A small rounded organ or structure.

atrioventricular n. 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: Tawara node. SEE: atrioventricular bundle; conduction system of the heart for illus.

Bouchard n. SEE: Bouchard nodes.

ectopic lymph n. 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 n. SEE: Heberden nodes.

lymph n. 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: conglobate gland; lymph gland. SEE: illus.; immune response; inflammation; lymph; 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 ...

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