S
- saliva
- A viscous secretion of salivary glands.
- second messenger
- A small molecule generated inside cells in response to binding of a hormone to cell surface receptors. Examples include cyclic AMP and calcium.
- secretin
- A peptide hormone synthesized in the small intestine and brain. One major activity of this hormone is to stimulate bicarbonate secretion from the pancreas.
- semen collection
- Collection of semen from males for analysis or insemination.
- serosa
- The outermost tunic of a tubular organ such as the intestine.
- SGLUT1
- A membrane transporter that co-transports sodium and a hexose (glucose or galactose) into cells. Important in the absorption of those sugars from the small intestine, and in the kidney.
- sinusoids
- A type of blood vessel lined with endothelial cells but having little or no wall. Found in several organs, including the liver.
- sodium pump
- The Na(+)-K(+)-ATPase. A membrane protein that pumps 3 sodium ions out of cells in exchange for 2 potassium ions in a reaction that hydrolyzes ATP. Critical in maintaining low intracellular sodium and resting membrane potential.
- sodium-iodide symporter
- A transporter protein that cotransports sodium and iodide ions into cells. Found predominantly in the thyroid gland, where it is sometimes called the "iodine trap".
- sodium-potassium ATPase
- The so-called sodium pump. A membrane protein that pumps 3 sodium ions out of cells in exchange for 2 potassium ions in a reaction that hydrolyzes ATP. Critical in maintaining low intracellular sodium and resting membrane potential.
- somatostatin
- A peptide hormone secreted by many tissues that tends to suppress secretion of other hormones.
- somatotropin
- Also known as growth hormone, a protein hormone secreted from the anterior pituitary that has potent metabolic and growth-promoting activities.
- space of Disse
- The space between hepatocytes and endothelial cells lining sinusoids in the liver.
- sperm morphology
- The shape of sperm and differences between normal and abnormal shapes.
- sperm motility
- The pattern of how sperm swim and move.
- sperm transport
- Usually refers to movement of sperm in the female reproductive tract.
- sphincter
- A ringlike band of muscle that constricts a passage or closes a natural orifice. Examples include esophageal sphincters and the anal sphincter.
- steroid
- A hydrophobic molecule derived from cholesterol, which itself is a steroid. Many steroids function as hormones.
- steroidogenesis
- The synthesis of steroids, usually referring to steroid hormones.
- stomach
- A section of the digestive tract.
- stroma
- The structural elements or framework of an organ, as distinguished from its functional components or parenchyma
- submucosal plexus
- A group of autonomic neurons in the enteric nervous system; also known as the plexus of Meissner.
- syncytium
- A multinucleated cell which results either from fusion of two or more cells, or from incomplete cell division where the nuclei but not the cell divides.
Last updated on 1/17/2005