Postcapillary resistance back sluice gate shunt venule true capillary Precapillary sphincter N arteriole thoroughfare Precapillary resistance channel front sluice gate postarterial Microcirculation后微动脉 venule true capillary A-V shunt Precapillary sphincter arteriole postarteriole thoroughfare Precapillary resistance channel Microcirculation （ front sluice gate） Postcapillary resistance （ back sluice gate ）