Dictionary

pineocytoma See pinealoma.

pinguecula A yellow spot on the conjunctiva (the membrane that lines the sclera—the “white” of the eye—and the eyelids) usually toward the inside of the eye, that is believed to be related to ultraviolet light exposure or other irritants. A pinguecula looks fatty and is due to an accumulation of connective tissue. Also known as…

pinguicula See pinguecula.

pinkeye See conjunctivitis.

pinna 1 The ear. 2 The part of the ear that projects like a wing from the head.

pinworm infestation An infestation of the intestinal tract by small, white pinworms (Enterobius vermicularis). Pinworms are about the length of a staple, and they live for the most part within the human rectum. While a pinworm-infested person is asleep, female pinworms leave the intestines through the anus and deposit eggs on the skin around the…

piriformis syndrome Irritation of the sciatic nerve that is caused by compression of the nerve within the buttock by the piriformis muscle. Typically, the pain of piriformis syndrome is increased by contraction of the piriformis muscle, prolonged sitting, or direct pressure applied to the muscle. Buttock pain is common. Piriformis syndrome can cause difficulty walking…

pit, preauricular See ear pit.

pituitary 1 Pertaining to the pituitary gland or its hormonal secretions. 2 The pituitary gland.

pituitary, anterior The front portion of the pituitary gland. Hormones secreted by the anterior pituitary influence growth, sexual development, skin pigmentation, thyroid function, and adrenocortical function. These influences are exerted through the effects of pituitary hormones on other endocrine glands, except in the case of growth hormone, which acts directly on cells. The effects of…

pituitary, posterior The back portion of the pituitary gland. The posterior pituitary secretes the hormone oxytocin, which increases uterine contractions and antidiuretic hormone (ADH), which increases reabsorption of water by the tubules of the kidney. Underproduction of ADH results in diabetes insipidus, which is characterized by inability to concentrate the urine and, consequently, excess urination,…

pituitary adenoma A benign tumor of the pituitary gland, the master gland that controls other glands and influences numerous body functions, including growth. Although a pituitary adenoma itself is not cancerous, it may affect pituitary function and therefore may need to be removed. See also pituitary gland; gigantism, pituitary.