Ans. c. Plav a role in thermoregulation Cutaneous (anterior-venous anastomosis) shunt vessels play an important role in temperature thermoregulation.Functional Classification of Vessel WaltVesselIncludeFeatureElastic ArteriesAorta, pulmonary artery and major branches* Elastic recoil maintains continuous blood flow and diastolic arterial pressure0Conduct (muscular) ArteriesMain arteries e.g. cerebral, coronary, popliteal, radial* Thicker muscle in tunica mediaResistance vesselsSmallest terminal arteries and arterioles* Single layer of muscle in tunica media* Regulate local blood flow to match local demandsArteriovenous anastomosisShunt vessels* Connect arteriole to venule by passing capillaries* Present in skin and nasal mucosa* Regulate temperatureExchange vesselsCapillaries* Largest cross section area* Provide O2 and nutrition to tissues0Capacitance vesselsVeins* Store large volumes of bloodArteriovenous Anastomosis {Shunt Vessels)* Shunt vessels are short muscular vessels that connect arterioles and venules, by passing the capillaries,* Like other vascular smooth muscles the shunt vessels are under the control of sympathetic nervous system (and receive sympathetic innervation)* Uneven distribution: shunt vessels are mainly concentrated in tissue with a small surface area / volume ratio e.g. fingers, toes, ears, and nose.Shunt vessels are found in skin and nasal mucosa especially inHandsPalm and fingersFeetSole and toesFaceEar, nose and lips* No nutritive only thermoregulatory function: Nutrition is provided by capillaries since capillaries deliver O2 to tissues. Because shunt vessels bypass capillaries, these have no nutritive function.* Shunt vessel have important role in thermoregulation. These provide an important site of hodV heat transfer between skin and blood stream. By dilating in cold conditions and directing large volumes of blood through these vessels, it provides a valuable mechanism to prevent tissue freezing and cold damage to the extremitiesQ