Dictionary

atelectasis Failure of full expansion of the lung at birth, or lung collapse thereafter. Also known as collapsed lung.

ATCC American Type Culture Collection.

ataxia-telangiectasia A progressive disease characterized by degeneration of the nervous system manifest by poor coordination and balance (cerebellar ataxia), red eyes due to widening of small blood vessels in the conjunctiva (ocular telangiectasia), and recurrent sinus and lung infections. Abbreviated AT. Patients with AT have a striking predisposition to leukemia and lymphoma and are extremely…

ataxia Poor coordination and unsteadiness due to the brain’s failure to regulate the body’s posture and regulate the strength and direction of limb movements. Ataxia is usually due to disease in the cerebellum of the brain, which lies beneath the back part of the cerebrum.

asystole A dire form of cardiac arrest in which the heart stops beating and there is no electrical activity in the heart. As a result, the heart is at a total standstill.

asymptomatic Without symptoms. For example, an asymptomatic infection is an infection with no symptoms.

astrocytoma A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes. The location of the tumor depends on the age of the person. In adults, astrocytomas most often arise in the cerebrum, whereas in children, they may arise in the brain stem, cerebrum, and cerebellum.

astigmatism A common form of visual impairment in which part of an image is blurred due to an irregularity in the dome-shaped curvature of the front surface of the eye, the cornea. With astigmatism, light rays entering the eye are not uniformly focused on the retina. The result is blurred vision at all distances. Significant…

asthma, thermally induced See asthma, exercise-induced.

asthma, exercise-induced Asthma triggered by vigorous physical activity. It primarily affects children and young adults because of their high levels of physical activity, but it can occur at any age. Exercise-induced asthma is initiated by the fall in airway temperature during rapid breathing followed by rapid reheating with lowered ventilation. The more heat that is…

asthma A common lung disorder in which inflammation causes the bronchi to swell and narrow the airways, creating breathing difficulties that may range from mild to life-threatening. Symptoms include shortness of breath, cough, wheezing, and chest tightness. The diagnosis of asthma is based on evidence of wheezing and is confirmed with breathing tests. Many allergens…

asthenic 1 Having a slender, light body. Ectomorphic. 2 Weak. Lacking in strength.