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The bony and muscular structure that forms the roof of the mouth and separates the oral and nasal cavities.

Elaborate and overly suspicious thoughts and feelings of persecution.


Parasympathetic nervous system:

Part of the nervous system that, together with the sympathetic nervous system, forms the autonomic nervous system (ANS). The ANS controls the functioning of involuntary structures, including the heart, glands, and smooth muscle. The parasympathetic nervous system regulates nerve transmissions to certain effector organs under normal conditions, as opposed to times of stress. It serves to “steady” involuntary activities and conserve or restore energy. Parasympathetic responses may include slowing of the heart and breathing rates, contraction of the pupils, an increase in glandular activity, and an acceleration in the rate of peristalsis.

Parathyroid glands:

Two pairs of endocrine glands located in the neck at the back of the thyroid gland. The parathyroid glands produce parathyroid hormone, which increases blood calcium levels by causing bones to release calcium into the blood, the kidneys to conserve calcium, and the intestines to increase calcium absorption from food. When blood calcium levels are high, the parathyroid glands reduce their production of parathyroid hormone, essentially reversing the process.


Abnormal sensations occurring spontaneously or in response to stimulation. Paresthesias may include prickling, tingling, burning, or tickling feelings; numbness; “pins and needles”; or cramp-like sensations. Various neurologic movement disorders may be characterized by paresthesias, including restless legs syndrome (RLS), paroxysmal kinesigenic dyskinesia (PKD), and paroxysmal non-kinesigenic dyskinesia (PNKD).

Parkinson’s disease (PD): 

A slowly progressive degenerative disorder of the central nervous system characterized by slowness or poverty of movement (bradykinesia), rigidity, postural instability, and tremor primarily while at rest. Additional characteristic findings include a shuffling, unbalanced manner of walking; forward bending or flexion of the trunk; a fixed or “mask-like” facial expression; weakness of the voice; abnormally small, cramped handwriting (micrographia); depression; or other symptoms and findings. Such abnormalities are thought to result from progressive loss of nerve cells within a certain region of the substantia nigra of the brain and the associated depletion of the neurotransmitter dopamine.


A constellation of the following symptoms: tremor, rigidity, bradykinesia (slow movements), and loss of postural reflexes. Although classically seen in Parkinson’s disease, parkinsonism may have other causes. In the elderly, parkinsonism may be caused by dopamine-blocking drugs, multiple system atrophy, striatonigral degeneration, Shy-Drager syndrome, cortico basal degeneration, diffuse Lewy body disease, and Alzheimer’s disease with parkinsonism. In younger people, parkinsonism may be caused by juvenile-onset dystonia/parkinsonism, Westphal variant of Huntington’s disease, Wilson’s disease, L-dopa-responsive dystonia, Hallervorden-Spatz disease, and progressive pallidal degeneration.


Pertaining to or occurring in paroxysms or sudden, recurrent episodes. The term paroxysms often describes transient episodes of abnormal involuntary movements (e.g., chorea, athetosis, dystonia, and/or ballismus) or ataxia, which is characterized by an impaired ability to coordinate voluntary movements.

Paroxysmal movement disorders:

Certain neurologic movement disorders characterized by abrupt, transient episodes of abnormal involuntary movement, such as chorea, athetosis, dystonia, and/or ballismus (i.e., the paroxysmal dyskinesias) or impaired coordination of voluntary actions and other associated findings (i.e., paroxysmal ataxias). Depending upon the specific disorder present, episodes may be precipitated or worsened by different factors. As examples, in those with paroxysmal kinesigenic dyskinesia (PKD), episodes may be triggered by sudden voluntary movements. In non-kinesigenic dyskinesia (PNKD), episodes occur spontaneously and may be worsened by caffeine or alcohol consumption, stress, fatigue, or other factors. In patients with paroxysmal kinesigenic ataxias, episodes may be triggered by sudden voluntary movements or postural changes. These disorders may be familial, appear to occur randomly for unknown reasons (sporadically), or occur secondary to other underlying conditions or disorders (symptomatic).


the origination and development of a disease.


The effects of disease on body functions; the physiology of altered function seen in disease. (“Patho-” is a combining form denoting any disease state, and “physiology” refers to the study of the processes and functioning of the human body).


The regularity or frequency with which a specific gene yields its effect or “is expressed.” For example, if a specific gene produces a disease in all individuals who carry the gene, it is termed 100% penetrant. If a gene produces the disease less than 100% of the time, it is not fully penetrant.


Peptides are short chains of amino acids.


The pericardium is the two-layered sac that surrounds and protect the heart. If the pericardium becomes fibrotic or filled with fluid, it limits the motion of the heart and, therefore, the ability of the heart to pump efficiently.

Periodic apnea:

Episodes of the temporary cessation of spontaneous breathing. Periodic apnea may be characterized by absence of airflow, absence of chest wall movements, or airway obstruction that may result from poor control of tongue movements, impaired coordination of upper airway muscles, or other abnormalities.

Periodic limb movements in sleep (PLMS):

Repeated stereotypic movements of the limbs (usually the legs) that occur during sleep. These movements typically consist of upward extension of the great toe and foot as well as flexion of the ankle, knee, or hip; they occur every 15 to 40 seconds and 0.5 to 6.0 seconds, usually during NREM sleep and have a duration of 0.5 to 6.0 seconds.

Peripheral edema: 

unusual fluid accumulation, resulting in swelling of the arms or legs.

Peripheral nervous system:

The peripheral nervous system is that portion of the nervious system outside of the brain and spinal cord (central nervous system).

Peripheral neuropathy:

Inflammation, degeneration, or damage of nerves of the peripheral nervous system (PNS). The PNS includes nerves that extend from the brain and spinal cord (central nervous system) to various parts of the body. Peripheral neuropathy may involve motor nerves, causing muscle weakness, and/or sensory nerves, resulting in pain, abnormal sensations, such as numbness or tingling, or other findings.


Rhythmic, wave-like contractions of smooth or involuntary muscle fibers that propel food through the digestive tract.


classification based on a scientific explanation.


an essential amino acid that is converted in the body to tyrosine.


an inherited disorder that, if untreated, causes profound mental retardation as well as other medical problems.


The production of speech; utterance of sounds through use of the vocal cords.


a physician specializing in physical medicine and rehabilitation.

Physiologic tremor:

A form of rapid tremor that may occasionally occur in any individual. Physiologic tremor is typically the result of fear, anxiety, or excitement. Physiologic tremor may affect the arms, legs, and, in some patients, the face or neck.


A placebo is a substance that appears to be identical to the treatment under study but that has no effects on the test subject. The placebo is given to members of the control group during experimental trials that test the effects of a drug or other substance.

Placebo-controlled trial: 

A placebo-controlled trial is a clinical experiment in which patients have been randomly assigned to receive either the treatment under study or placebo, an alternative that has no effects.


The pleura are the two-layer membranes that cover the outside of the lungs and line the chest cavity.

Polymerase chain reaction (PCR): 

A highly sophisticated technique during which a known sequence of DNA is copied rapidly over a short period, such as millions of copies over a few hours. PCR testing assists in diagnosing certain genetic disorders, helps identify individuals through analysis of a single cell or so-called “DNA fingerprinting,” or characterizes certain strains of infectious microorganisms.

Positron emission tomography (PET):

An advanced, computerized imaging technique that uses radioactively-labels substances (e.g., glucose) to demonstrate chemical and metabolic activities in the brain as well as track other brain functions. Brain structures are also visualized on PET scans.

A noninvasive, diagnostic procedure used to record the uptake and distribution of certain substances in the tissues and organs of the body. Thus, PET assists in evaluating various metabolic and physiological activities in the body. During this procedure, three-dimensional, color-coded images are created based upon the detection of positively charged particles (positrons). The positrons are produced by certain biochemicals (e.g., glucose) carrying radioactive substances that have been introduced into the body (via intravenous injection). PET scanning may help to detect abnormal biochemical patterns associated with certain neurologic conditions, such as Parkinson’s disease, brain tumors, seizure disorders, and psychiatric abnormalities.

Positron emission tomography (PET) scanning:

Postural instability:

 unsteadiness of gait or standing.

Postural tremor:

 Any tremor that is present while an individual voluntarily maintains a position against gravity, such as holding the arms outstretched.


Literally a “forerunner,” such as a substance that precedes another in a biochemical reaction.


Before birth.


A genetic probe is a single strand of DNA or RNA with a specific base sequence used to detect the corresponding base sequence by hybridization—which is the process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule. The single strand is either radioactively or immunologically labeled.

Progressive supranuclear palsy (PSP):

A progressive neurological disorder characterized by neurodegenerative changes of certain brain regions, including particular areas of the basal ganglia and the brainstem. Symptom onset most often occurs in the sixth decade of life. Associated findings may include balance difficulties, sudden falls, stiffness (rigidity), slowness of movement (bradykinesia), an impaired ability to perform certain voluntary eye movements, and visual disturbances. Affected individuals may also develop slurred speech; swallowing difficulties; personality changes; dystonia; sudden, involuntary, “shock-like” muscle contractions (myoclonus); or other abnormalities. The disorder usually appears to occur randomly for unknown reasons (sporadically); however, there are some reports of families with multiple affected members, suggesting a possible hereditary component to the disease.


Referring to preventive treatment (i.e., prophylaxis); a medication, procedure, or device that serves as a preventive against disease.


Protection from or the prevention of disease; preventive (i.e., prophylactic) therapy; often refers to the use of a drug, mechanical agent, or procedure to prevent infection with certain microorganisms (e.g. bacteria).

Proteasome inhibitor:

A proteasome inhibitor is a chemical that interferes with, or inhibits, the action of proteasomes—the recyclers of proteins in the cells.


Proteins are large complex molecules made up of amino acids. Each protein starts out as a chain of amino acids. Determined by the sequence of the base pairs in the gene that encodes it, the protein then folds itself into its unique shape. Proteins serve many different roles within the body, including providing structure (collagen), allowing movement (actin and myosin), increasing the rate of a chemical reaction (enzymes), transporting substances (hemoglobin); regulating processes within the cells (insulin); and responding to the stimuli (receptor proteins on surface of all cells).


Of mental or emotional origin; referring to a symptom, condition, or disorder that is caused by mental, psychological, or emotional factors rather than physical illness.


Refers to any mental disorder characterized by severe distortion of thinking, comprehension, and judgment (i.e., mental capacity); impaired contact with reality; and abnormal emotional responses and disorganized behaviors. Symptoms may include false beliefs despite evidence to the contrary (delusions), such as fears of persecution; the perception of sounds, sights, or other sensations in the absence of external stimuli (hallucinations); apparent lack of emotion (affect); abnormal thought patterns; disorganized, incoherent speech; and/or agitated, aggressive behaviors. Psychosis may be of physical (i.e., organic) origin, such as due to brain damage, neurological diseases, underlying metabolic disorders, etc., or “functional,” meaning that it is produced or caused by factors other than organic disease.


Referring to the lungs. 

Pulmonary fibrosis:

Pulmonary fibrosis is a condition in which excessive scar tissue forms in the lungs, making them stiff, decreasing the amount of surface area that is available to provide gas exchange, and interfering with their function.


ne of the 3 major brain regions that, together with the caudate nuclei and the globus pallidus, comprise the basal ganglia. Relatively similar in function and structure, the putamen and the caudate nuclei are collectively referred to as the striatum. Specialized groups of nerve cells within the putamen receive input from various regions of the cerebral cortex. The messages are processed and relayed by way of the thalamus to the motor cortex, influencing voluntary movement.


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