They serve the body as a natural filter of the blood, and remove water-soluble wastes which are diverted to the bladder. In producing urine, the kidneys excrete nitrogenous wastes such as urea and ammonium. They are also responsible for the reabsorption of water, glucose, and amino acids. The kidneys also produce hormones including calcitriol and erythropoietin.
Definition of skeg. 1  1 : the stern of the keel of a ship near the sternpost; especially : the part connecting the keel with the bottom of the rudderpost in a single-screw ship. 2  2 : a fin situated on the rear bottom of a surfboard that is used for steering and stability.
As soon as you have changed the focus to the stern, adjusting the skeg becomes simple. Main reason to use a skeg is to use less work to keep on the course you want the kayak to be on. (That is, the skeg affects how much the kayak turns in wind and waves). Especially when paddling with the wind and waves coming partly from the side, it means the skeg can be used to be able to keep the course with little work.