2,701 articles
Pubarche
Pubarche is the first appearance of pubic hair, an androgen-driven milestone of puberty driven by adrenal DHEA/DHEAS. Early onset (before 8 in girls, 9 in boys) is usually benign premature adrenarche; virilizing disorders cause 5–10%.
Puberty
Puberty is the transition from childhood to adulthood, marked by a growth spurt, secondary sexual characteristics, and fertility, typically beginning between ages 8 and 14.
Pubic hair
Pubic hair is terminal hair on the genital skin that appears at puberty under androgen influence (pubarche/adrenarche). It protects and ventilates the genital region; removal is widespread but carries infection and injury risks.
Pubic symphysis
Pubic symphysis (symphysis pubica): the midline secondary cartilaginous joint uniting the left and right pubic bones, with a fibrocartilage disc, four ligaments, 3-6 mm adult width, small physiological motion, and pregnancy-related widening.
Pubis (bone)
Pubis (os pubis, pubic bone): smallest of the three hip-bone bones, forming the anteroinferior pelvis with body, superior and inferior rami, pubic symphysis, and one fifth of the acetabulum.
Pudendal nerve
Pudendal nerve (Alcock's canal nerve), paired S2–S4 sacral plexus nerve supplying perineum, genital sensation, and anal and urethral sphincters; compression causes pudendal neuralgia, diagnosed by Nantes criteria and treated with blocks, stimulation, or decompression.
Pulmonary artery
Pulmonary artery (pulmonary trunk): the vessel carrying deoxygenated blood from the right ventricle to the lungs; about 5 cm long, 2-3 cm wide, bifurcates at T4; low-pressure, high-capacitance system with resistance about one-tenth systemic.
Pulmonary artery banding
Pulmonary artery banding (PAB) is a palliative heart operation, introduced by Muller and Dammann in 1951-1952, that constricts the pulmonary artery to cut excessive lung blood flow in congenital defects, single-ventricle palliation, and infant heart failure.
Pulmonary artery endothelial cell
Pulmonary artery endothelial cells (PAECs) line the pulmonary arteries; markers include CD31, vWF, VE-cadherin. Distinct from microvascular ECs; central to PAH endothelial dysfunction, low NO, glycolytic shift, and anoikis resistance research.
Pulmonary atresia with intact ventricular septum
Pulmonary atresia with intact ventricular septum (PA-IVS) is a rare congenital heart defect in which the pulmonary valve fails to develop, causing cyanosis in newborns.
Pulmonary circulation
Pulmonary circulation carries deoxygenated blood from the right ventricle through the pulmonary arteries to the lungs and returns oxygenated blood to the left atrium; a low-pressure, low-resistance circuit first described by Ibn Al-Nafis.
Pulmonary Diffusing Capacity
Pulmonary diffusing capacity (DLCO, TLCO) measures carbon monoxide transfer from alveoli to blood, reflecting membrane area, capillary blood volume, and hemoglobin; developed by Marie Krogh in 1915 and standardized by Ogilvie in 1957.
Pulmonary surfactant
Pulmonary surfactant (lung surfactant) is a lipid-protein mixture secreted by type II alveolar cells that lowers alveolar surface tension to near 0 mN/m, preventing collapse; deficiency causes neonatal RDS, treated with animal-derived or synthetic surfactant replacement.
Pulmonary valve
Pulmonary valve (pulmonic valve, valva trunci pulmonalis): the heart's three-cusp semilunar valve between right ventricle and pulmonary trunk; opens in systole, closes in diastole; disorders include stenosis, regurgitation, atresia.
Pulmonary vein
Pulmonary veins: typically four vessels (right/left superior and inferior) carrying oxygenated blood from the lungs to the left atrium; sites of atrial fibrillation origin, congenital anomalies like TAPVR, and post-ablation stenosis.
Pulmonic valve disease in adults
Pulmonic valve disease in adults is narrowing (pulmonic stenosis) or leaking (pulmonary regurgitation) of the valve between the right ventricle and the pulmonary artery, usually congenital in origin.
Pulsatile Flow
Pulsatile flow is the rhythmic, on-and-off movement of fluid through a blood vessel or piping system, produced in the body by the heart's cyclic pumping rather than steady laminar flow.
Pulse
Pulse: the arterial pulse and heart rate, a vital sign. Normal adult resting rate 60-100 bpm; measured at radial, carotid, and other sites; history from Herophilus to sphygmograph and modern PPG wearables.
Pulse pressure
Pulse pressure (PP) is systolic minus diastolic blood pressure, normally about 40 mmHg. Determined by stroke volume, arterial stiffness, and wave reflection; a wide PP predicts cardiovascular risk, a narrow PP suggests shock or tamponade.
Pulsed electromagnetic field therapy
Pulsed electromagnetic field (PEMF) therapy, also called pulsed electromagnetic field stimulation, is a noninvasive treatment using coil-generated magnetic fields to induce healing currents in bone; FDA first approved it in 1979 for fracture nonunions, with mixed evidence in osteoarthritis and pain.
Pulseless electrical activity
Pulseless electrical activity (PEA), formerly electromechanical dissociation, is a non-shockable cardiac arrest rhythm with organized ECG activity but no palpable pulse; treated with CPR, epinephrine, and reversal of causes.
Pulsus paradoxus
Pulsus paradoxus: inspiratory systolic blood pressure fall over 10 mmHg, a sign of cardiac tamponade, constrictive pericarditis, severe asthma, and COPD; named by Kussmaul in 1873.
Pupil
Pupil (pupilla): the central aperture of the iris through which light enters the eye. Size is set by parasympathetic sphincter pupillae constriction and sympathetic dilator pupillae dilation; measured by pupillometry.
Pupillary light reflex
Pupillary light reflex (PLR): involuntary pupil constriction to light via retina, optic nerve (CN II), pretectal area, Edinger-Westphal nucleus, CN III, ciliary ganglion; tested by swinging flashlight test for RAPD.
PURE study
PURE (Prospective Urban Rural Epidemiology) study: international McMaster/PHRI prospective cohort of ~225,000 adults aged 35–70 in 27 countries, studying societal and behavioral determinants of cardiovascular disease, diet, and mortality, with noted dietary and sodium methodology criticisms.
Purkinje cell
Purkinje cell: large GABAergic neuron of the cerebellar cortex, discovered by Jan Evangelista Purkyně in 1837; sole output of cerebellar cortex, inhibiting deep cerebellar nuclei and mediating motor learning plasticity.
Purkinje fibers
Purkinje fibers: specialized glycogen-rich cardiac muscle cells forming the terminal subendocardial network of the heart's conduction system, discovered by Jan Evangelista Purkinje in 1839 in sheep, conducting at 2–3 m/s and acting as backup ventricular pacemaker.
Putrefaction
Putrefaction: microbe-mediated stage of corpse decomposition, following autolysis, in which gut and environmental bacteria digest tissue, producing gases, bloating, discoloration, and venous marbling; rate depends on temperature and health, and microbial succession now supports forensic time-of-death estimation.
Pvalb chandelier GABAergic interneuron
Pvalb chandelier GABAergic interneuron, also called chandelier cell or axo-axonic cell, is a fast-spiking parvalbumin interneuron whose cartridge boutons exclusively target pyramidal axon initial segments, with links to epilepsy, schizophrenia, and autism.
Pylorus
Pylorus: the stomach-duodenum junction with the pyloric sphincter, a smooth-muscle valve regulating gastric emptying. Key disorders are pyloric stenosis, gastroparesis-related pylorospasm, and bile reflux; G-POEM treats refractory gastroparesis.