in humans

• active transport is used in the gut when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood
• higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood
• sometimes theres a lower concentration of nutrients in the gut then there is in the blood
• glucose can be taken into the bloodstream when the concentration in the blood is higher than in the gut, it can be transported to cells for respiration