1 Ghrelin is a fast-acting hormone that plays a vital role in meal initiation and contributes to weight gain. 2  Leptin mediates long-term regulation of energy balance and suppresses food intake, thereby inducing weight loss.  Both hormones can be controlled naturally, primarily though exercise and stress management.
Surgical retractors. A retractor is a surgical instrument with which a surgeon can either actively separate the edges of a surgical incision or wound, or can hold back underlying organs and tissues, so that body parts under the incision may be accessed. The two are each available in many shapes, sizes, and styles.
Surgical retractors come in a wide assortment of shapes, sizes, and designs. They are typically referred to in terms of the type of tissue or organ to be retracted; some examples include abdominal retractors, lung retractors, and skin retractors. Many varieties, such as the Balfour retractor, are named after the person who invented them.