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.
Others hold back organs that may naturally block the operative field to give the surgeon clear access. Instruments used to force tissues apart and then hold them in position, such as rib spreaders, may also be considered retractors. Ad. The two main types of surgical retractors are hand-held and self-retaining. Hand-held retractors are designed to be held by assistants during the surgical procedure. Self-retaining retractors can be adjusted and locked in place so they maintain their position without further manual intervention.