You couldnt survive without your skin. It has many important functions. The main function of the skin is controlling what enters and leaves the body. It prevents the loss of too much water from the body. It also prevents bacteria and other microorganisms from entering the body. The skin helps maintain a constant body temperature. It keeps the body cool in two ways. Sweat from sweat glands in the skin evaporates to cool the body. Blood vessels in the skin dilate, or widen. This action increases blood flow to the body surface. This allows more heat to reach the surface. The heat is then able to radiate off the body. The opposite happens to retain body heat. Blood vessels in the skin constrict, or narrow. This decreases blood flow to the body surface. This reduces the amount of heat that reaches the surface. When this happens, less heat can be lost to the air.

What decreases blood flow to the body's surface?

Befitting a lush, tropical island stranded in the middle of the ocean, Madeira's origins are shrouded in mystery and fanciful legend. Some claim that the archipelago is what remains of Plato's lost Atlantis, or part of a landmass that once fused the continents of Europe and America. The Portuguese Step Ashore: Recorded history of the volcanic archipelago begins in relatively recent times: 1418, just as the golden age of Portuguese discovery was erupting. Under the leadership of Henry the Navigator, caravels set out from the westernmost point of the Algarve, in southern Portugal, in search of foreign lands, fame, and wealth. Joao Goncalves Zarco, sailing in the service of Prince Henry, made the first of many famous Portuguese discoveries, which would culminate a century later in Magellan's historic circumnavigation of the globe. Zarco happened upon a small volcanic archipelago 1,000 km from Lisbon. Perhaps Zarco knew precisely where he was heading, having learned of the existence of Madeira from a Castilian source. After all, the waters of the Canary Islands, only 445 km (275 miles) to the south, had occupied busy shipping lanes for very nearly a century, and Genovese maps from the mid-14th century depict both Madeira and Porto Santo. More likely, Zarco was heading for Guinea and storms forced him onto the beach of Porto Santo. If so, then he was extremely fortunate, for he managed to land on the only large, sandy beach for hundreds of miles around. Little wonder he subsequently named it Porto Santo (Holy Port). The following year Zarco returned to claim the larger island he had seen from Porto Santo, and with him went Tristao Vaz Teixeira and Bartolomeu Perestrelo. They officially became the first men to set foot on the heavily forested island, naming it Ilha da Madeira, "Island of Timber. " The Portuguese Crown, delighted with its first important discovery, immediately embarked on a program of colonization. Zarco and Teixeira were appointed co-governors of Madeira, while Perestrelo was awarded Porto Santo.

Zarco happened upon a small volcanic archipelago near Lisbon following the orders of which leader?

Rough surfaces create more friction than smooth surfaces. Thats why cars have tires. Its also why we use rubber mats in areas that might get wet. In your bathtub, you may even use No-Slip tape. No-slip is another way of saying the items has a lot of friction. In Figure 1.9, the blades of the skates are very smooth. Thats why you cant slide across ice with shoes. The soles of your shoes are much rougher than skates. The rougher surface of shoes causes more friction and slows you down. Heavier objects also have more friction. A heavy object presses down with more force. The surfaces are held together more tightly. This makes the surfaces harder to slide past each other. Did you ever try to push something heavy across the floor? Heavy objects are much harder to push than light objects.
Why do we use rubber mats in areas that might get wet?