1) The heart becomes three-chambered.
2) Two circles of blood circulation are formed. In a small circle, blood from the ventricle enters the lungs, is saturated with oxygen and enters the left atrium. In a large circle, blood from the ventricle goes to the organs of the body, and from there to the right atrium.
3) The body receives mixed blood.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.