Nitrogen-containing organic bases including thymine, cytosine and uracil, which pair with purines in DNA and RNA and whose derivatives are important in cellular metabolism and which are essential components of nucleic acids. They are not only found in nucleic acids, but also in amino acids, antibiotics, vitamins and even a variety of toxins. Pyrimidines have …
Category Archives: Uncategorized
Purkinje cell layer
Also referred to as the piriform (pear-shaped) neuronal layer in the past, it is the layer of Purkinje neurons (and Bergmann glia) situated between the external molecular layer and the internal granular layer of the cerebellar cortex. It is considered to be the deepest of the molecular layers. See Cerebellar cortex, Cerebellum (anatomy), Glial cells, Granular layer, …
Pupillometry
Diameter of the pupil of the human eyedoes not only change in response to variations in ambient light (pupillary light reflex), but it additionally responds to the perception of arousing oremotionally relevant stimuli and to the increased cognitive load caused bymemory demands (e.g., by increasing the span of a string of digits to be remembered),or …
Purines
One of several nitrogen-containing organic bases, of which adenine and guanine are the most common, that pair with pyrimidines in DNA and RNA and whose derivatives are important in metabolism. Together with the synthesis of pyrimidines, purines form a crucial pathway for the functioning of a number of amino acids. Meat and associated products, as …
Pupil Evaluation Inventory
A form of peer assessment like the Revised Class Play of male and female children from grade one to nine. . See Revised Class Play, Sociometry
Pulsatility index (PI)
A measure of thedifference in blood flow velocities in systole and diastole used in Dopplerultrasound of fetal and placental vessels. PI is calculated as the (Velocitysystole– Velocitydiastole / Velocityaverage). See Placenta, Velocity
Pulvinar
From the Latin for a ‘cushion’, it is the most caudal nucleus of the thalamus situated over the posterior aspect of the internal capsule. Anatomically, it is distinguished in terms of lateral, inferior, medial and oral sub-nuclei that have (somewhat blurred) topographical connections with association areas in the cerebral cortex: the lateral and inferior pulvinar have …
Psychosocial stress
Adverse social circumstances, hardship, problematic social relationships, emotional distress, and misfortunes that bind, or even strain and overtax, the psychological and social resources of a person. When such stress becomes chronic in developing children, it can adversely affect their gut health, especially short-chain fatty acids as well as a range of immunological diseases. The well-researched adverse effects of psychosocial stress …
Puberty
The process of maturing sexually and thus when sexual reproduction becomes possible. During puberty, major differences in composition, shape and size, as well as function, are attained in many body parts and systems, the most striking of which are secondary sexual characteristics. These changes are due to increasing levels of estradiol and testosterone taking place in …
Psychopathology
Broadly speaking, there are two meanings. Firstly, it is the scientific study of aberrant behaviours and mental disorders, and secondly it constitutes the collective signs and symptoms of a mental disorder. It is held that psychopathology should not be equated with psychopathy, the latter concerning anti-social personality disorders as well as criminality. See Diagnosis …