gland, thyroid A gland that makes and stores hormones that help regulate heart rate, blood pressure, body temperature, and the conversion of food to energy (metabolism). Thyroid hormones are also essential for proper growth and development. The thyroid gland is located in the lower part of the neck, below the Adam’s apple, wrapped around the…
glandular fever Infectious mononucleosis. See also mononucleosis.
glans 1 The glans penis, the rounded head of the penis. 2 The rounded head of the clitoris.
glans and foreskin, inflammation of the See balanoposthitis.
glans penis, inflammation of the See balanitis.
glaucoma A common eye condition in which the fluid pressure inside the eye rises because of slowed fluid drainage from the eye. If untreated, glaucoma may damage the optic nerve and other parts of the eye, causing the loss of vision or even blindness. There are no symptoms in the early stages of glaucoma. As…
glaucoma, angle-closure See angle-closure glaucoma.
gliadin A protein found in wheat and some other grains that is part of wheat gluten. People with celiac sprue, Crohn’s disease, and related conditions may be sensitive to gliadin in the diet. See also celiac sprue; Crohn’s disease; dermatitis herpetiformis.
glial cell A supportive cell in the central nervous system. Unlike neurons, glial cells do not conduct electrical impulses. The glial cells surround neurons and provide support for and insulation between them. Glial cells are the most abundant cell types in the central nervous system. Types of glial cells include oligodendrocytes, astrocytes, ependymal cells, Schwann…
glioblastoma multiforme A highly malignant, rapidly growing type of brain tumor that arises from glial cells in the brain. Early symptoms may include sleepiness, headache, and vomiting. Also called a grade IV astrocytoma. Treatment can involve surgery and radiation treatment.
glioma A brain tumor that begins in a glial cell in the brain or spinal cord. Malignant gliomas are the most common primary tumors of the central nervous system. They are often resistant to treatment and carry a poor prognosis. Astrocytomas are the most common glial tumors. See also glioma, optic.
glioma, optic A rare, most commonly benign tumor on the optic nerve or the optic chiasm (the crossing of the two optic nerves). Optic gliomas cause pressure and destruction of normal optic nerve tissue. They are most common in children and teens. Optic gliomas are strongly associated with neurofibromatosis (NF1).