A substitute or substitute good in economics and consumer theory is a product or service that a consumer sees as the same or similar to another product.
Postural orthostatic tachycardia syndrome (POTS) is one of a group of disorders that have orthostatic intolerance (OI) as their primary symptom.OI describes a condition in which an excessively reduced volume of blood returns to the heart after an individual stands up from a lying down position.n POTS, the lightheadedness or fainting is also accompanied by a rapid increase in heartbeat of more than 30 beats per minute, or a heart rate that exceeds 120 beats per minute, within 10 minutes of rising. The faintness or lightheadedness of POTS are relieved by lying down again.
Definition. Sjogren's (SHOW-grins) syndrome is a disorder of your immune system identified by its two most common symptoms â dry eyes and a dry mouth. Sjogren's syndrome often accompanies other immune system disorders, such as rheumatoid arthritis and lupus.In Sjogren's syndrome, the mucous membranes and moisture-secreting glands of your eyes and mouth are usually affected first â resulting in decreased production of tears and saliva.jogren's syndrome often accompanies other immune system disorders, such as rheumatoid arthritis and lupus. In Sjogren's syndrome, the mucous membranes and moisture-secreting glands of your eyes and mouth are usually affected first â resulting in decreased production of tears and saliva.