Mai karɓar alpha yana nufin nau'in furotin mai karɓa wanda aka kunna ta hanyar hormone adrenaline ko noradrenaline (wanda aka sani da epinephrine da norepinephrine, bi da bi), wanda glandan adrenal ke fitarwa don amsawa ga damuwa ko wasu abubuwan motsa jiki. Ana samun waɗannan masu karɓa a ko'ina cikin jiki, ciki har da magudanar jini, santsin tsoka, da zuciya, kuma suna taka rawa wajen daidaita hawan jini, bugun zuciya, da sauran ayyukan jiki. Akwai manyan nau'o'i biyu na masu karɓar alpha, waɗanda aka sani da alpha-1 da alpha-2 receptors, kowannensu yana da takamaiman ayyuka da tasirinsa.