In external respiration while occurs in internal respiration. oxygen moves from the alveoli to the pulmonary capillaries; carbon dioxide moves from the pulmonary capillaries to the alveoli. oxygen moves from the alveoli to the pulmonary capillaries; oxygen moves from the pulmonary capillaries to the alveoli. carbon dioxide moves from the alveoli to the pulmonary capillaries; carbon dioxide moves from the pulmonary capillaries to the alveoli. oxygen moves from the alveoli to the pulmonary capillaries; oxygen moves from the tissues to the systemic capillaries. oxygen moves from the alveoli to the pulmonary capillaries; carbon dioxide moves from the tissues to the systemic capillaries.