Preheat oven to 350 degrees F., and spray or grease an 8 x 4 inch loaf pan. In one bowl, mix together the flour, baking powder, and salt. In another bowl, using an electric hand mixer, beat the two eggs until blended. Add the oil, sugar, lemon juice and zest, and buttermilk, and beat until well mixed. Stir in the zucchini, then pour the dry ingredients into the bowl with the egg mixture and beat on low speed just until mixed. Gently fold in the blueberries, then pour the batter into the pan. Bake 50 to 55 minutes, or until a bamboo skewer or cake tester comes out clean when inserted into the center. Cool 10 minutes, then remove from the pan. Continue to cool to room temperature before slicing.