P

Palliative
Palliative means "relief of symptoms." Most often, palliation is the relief of pain.

Pallor
Unnatural lack of color in the skin (as from bruising or sickness or emotional distress)

Pancytopenia
An abnormal deficiency in all blood cells (red blood cells and white blood cells and platelets); usually associated with bone marrow tumor or with aplastic anemia

Panniculitis
Inflammation of subcutaneous fat.

Papilla (pl. papillae)
A hump or swelling.

Parenchyma
The essential elements of an organ, used in anatomical nomenclature as a general term to designate the functional elements of an organ, as distinguished from its framework or stroma.

Parietal Peritoneum
The peritoneum is a thin membrane that lines the abdominal and pelvic cavities, and covers most abdominal viscera. It is composed of layer of mesthelium supported by a thin layer of connective tissue. Parietal peritoneum is that portion that lines the abdominal and pelvic cavities.

Pathogen
A specific causative agent (such as a bacterium or virus) of disease.

Patency
The state of being freely open or exposed.

Perichondrium
The smooth serous membrane which lines the cavity of the abdomen, or the whole body cavity when there is no diaphragm, and, turning back, surrounds the viscera, forming a closed, or nearly closed, sac.

Peritoneum
The smooth serous membrane which lines the cavity of the abdomen, or the whole body cavity when there is no diaphragm, and, turning back, surrounds the viscera, forming a closed, or nearly closed, sac.

Petechiae
Pin-head-sized sites of bleeding in the skin. This type of bleeding results from a very low platelet count. The small punctate hemorrhages are frequently seen on the legs, feet, trunk and arms. They evolve from red to brown and are eventually disappear. They stop developing when the platelet count increases.

Peyer's patch
These are quite large aggregates of lymphoid tissue found in the small intestine, part of the lymphatic system which help to fight infection.

pH
A measure of acidity and alkalinity of a solution. The measure is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity. On the scale, each unit of change represents a tenfold change in acidity or alkalinity.

Pheochromocytoma
A tumor that is derived from chromaffin cells and is usually associated with paroxysmal or sustained hypertension.

Phenotype
A set of observable physical characteristics of an individual organism. A single characteristic can be referred to as a "trait," although a single trait is sometimes also called a phenotype. For example, blond hair could be called a trait or a phenotype, as could obesity. A phenotype can be the result of many factors, including an individual's genotype, environment, and lifestyle, and the interactions among these factors. The observed manifestation of a genotype, a phenotype may be expressed physically, biochemically, or physiologically.

Philadelphia chromosome
Characteristic chromosomal abnormality in which a portion of chromosome 22 is translocated to chromosome 9. This abnormality is found in nearly all cases of chronic myeloid leukaemia and some cases of acute lymphoblastic leukaemia.

Placenta
The vascular organ in mammals, except monotremes and marsupials, that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues.

Plasma
The fluid part of blood, lymph, or milk as distinguished from suspended material.

Plasmacytoma
Any discrete, presumably solitary, mass of neoplastic plasma cells either in bone marrow or various extramedullary sites.

Platelets
A particle found in the bloodstream that binds at the site
of a wound to begin the blood clotting process. Platelets are formed in bone marrow.

Pleura
The delicate serous membrane that lines each half of the thorax of mammals and is folded back over the surface of the lung of the same side.

Pleural Effusion
A collection of fluid (or blood) in the pleural space (in one side of the chest cavity around the lung). May be secondary to trauma, cancer, nephrotic syndrome, kidney disease, pancreatitis, congestive heart failure and cirrhosis.

Plicae circulares
Plicae circulares are macroscopically visible, crescent-shaped folds of the mucosa and submucosa. Plicae circulares extend around one-half to two-thirds of the circumference of the lumen of the small intestine.

Polypectomy
Excision of a polyp.

Primary Site
The anatomic site where the original tumor is located. Primary cancer is usually named after the organ in which it starts. For example, cancer that starts in the breast is always breast cancer even if it spreads (metastasizes) to other organs such as bones or lungs.

Process
Any marked prominence or projecting part.

Progesterone
A female steroid sex hormone C21 H30 O2 that is secreted by the corpus luteum to prepare the endometrium for implantation and later by the placenta during pregnancy to prevent rejection of the developing embryo or fetus.

Prognosis
The patient's potential clinical outlook based on the status and probable course of his disease.

Prolactin
Prolactin is produced from the anterior pituitary gland, it's found in the serum of normal females and males. Prolactin's principal physiological action is to initiate and sustain lactation.

Proliferation
The reproduction or multiplication of similar forms, especially of cells and morbid cysts.

Proptosis
Forward displacement (bulging) of an organ, typically the eyeball(s).

Protein
Any of numerous naturally occurring extremely complex substances that consist of amino-acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (as phosphorus or iron), and include many essential biological compounds (as enzymes, hormones, or immunoglobulins).

Proton
A proton is a subatomic particle found in the nucleus of every atom. The particle has a positive electrical charge, equal and opposite to that of the electron.

Puberty
The condition of being or the period of becoming first capable of reproducing sexually marked by maturing of the genital organs, development of secondary sex characteristics, and in the human and in higher primates by the first occurrence of menstruation in the female.

Puerperium
The period between childbirth and the return of the uterus to its normal size.

Purpura
Hemorrhage under a surface that is about 1.0 cm. in diameter.

Pyelogram
X-ray study of the kidney especially showing the pelvis (urine-collecting basin) of the kidney and the ureter.