H
- haploid
- Containing a single set of chromosomes. Mature eggs and sperm, and bacteria are examples of haploid cells.
- heartburn
- A painful sensation caused by reflux of acid from the stomach into the esophagus.
- hemacytometer
- A glass slide precision etched to allow counting of cells. Also known as a hemocytometer.
- hemolysis
- Destruction of red blood cells and release of hemoglobin.
- hemosiderin
- An iron-contaning complex related to ferritin.
- hepatic
- Pertaining to the liver
- hepatocyte
- The major functional cell in the liver
- herbivore
- An animal that eats plants. Examples include cattle, rabbits and grasshoppers.
- heterodimer (heterodimeric)
- A protein complex composed of two different proteins.
- heterodonty
- Having teeth of different shapes.
- hexose
- A simple sugar or monosaccharide that contains six carbon atoms. Important examples include glucose, galactose and fructose.
- hexose transporters
- Membrane proteins that transport hexoses into and out of cells.
- histology
- The study of the microscopic structure or anatomy of tissues.
- homeostasis
- Maintenance of a stable and balanced environment in the body. For example, calcium homeostasis refers to the mechanisms that keep concentrations of calcium within a "normal range" despite temporary excursions below and above.
- homodimer (homodimeric)
- A protein complex composed of two identical proteins.
- hormone
- A chemical messenger that binds to receptors on target cells, which leads to some change in that cells physiologic state.
- hydrocortisone
- A synonym for the hormone cortisol.
- hydrolysis
- A chemical reaction in which a covalent bond is broken with accompanying additon of water - a protein (H+) is added to one product and a hydroxyl (OH-) to the other.
- hydrostatic pressure
- Pressure of fluid in a system (e.g. vascular system or extracellular fluid). Often used as equivalent to osmotic pressure when dealing with flow of water across membranes.
- hygroma
- A fluid-filled sac, bursa or cyst. A cystic hygroma is lined with endothelial cells derived from the lymphatic system.
- hyper-
- Prefix meaning excess. Hypertension is the condition of blood pressure in excess of what is normal.
- hyperglycemia
- Abnormally high concentrations of glucose in blood.
- hyperkalemia
- Abnormally high concentrations of potassium in blood.
- hypernatremia
- Abnormally high concentrations of sodium in blood.
- hyperplasia
- An increase in number of cells (rather than cell size); often associated with an increase in organ size.
- hypertrophy
- An increase in size of cells (rather than number of cells); often associated with an increase in organ size.
- hypo-
- Prefix meaning below or deficient. Hypotension is the condition of blood pressure below normal.
- hypoglycemia
- Abnormally low concentrations of glucose in blood.
- hypokalemia
- Abnormally low concentrations of potassium in blood.
- hyponatremia
- Abnormally low concentrations of sodium in blood.
- hypophysis
- A major endocrine organ better known as the pituitary gland.
Last updated on 1/17/2005