There are walls called septa between the two atria and the two ventricles that prevent this mixing. Unborn infants have an opening (foramen ovale) that does allow this and it should close right after birth.
Because human's heart is four chambered. They prevent in mixing of oxygenated and deoxygenated blood.
I hope I answered your question.
in atria the deoxygenated and oxygenated blood donot mix due to the presence of inter atrial spectum and in ventricles the mixing is prevented by inter ventricular aperture.
The structure in the heart that separates oxygenated blood from deoxygenated blood is the atria. These are the two sides of the heart and are separated by the interatrial septum.
Oxygenated and deoxygenated blood do not get mixed up inside the heart because the heart was designed to keep these separate. This is why the heart is so complex.
It keeps the oxygenated and deoxygenated blood separate from each other.
Oxygenated
All blood is red, regardless of where it is in the body. Oxygenated blood and deoxygenated blood have slightly different shades, with deoxygenated blood being darker and oxygenated blood brighter.
In the main, except from the pulmonary artery and vein. The pulmonary artery carries deoxygenated blood from the heart to the lungs and the vein carries oxygenated blood from the lungs to the heart.
Veins carry deoxygenated blood from the tissues and organs to the heart. Arteries are the means for carrying the oxygenated blood.
The right heart chambers (atrium and ventricle) contain deoxygenated blood. The left heart chambers contain oxygenated blood, since this blood has already been through the pulmonary system.
The deoxygenated blood and the oxygenated blood would mix.
It stops the deoxygenated blood from mixing with the oxygenated blood in the heart
Pulmonary vein carries oxygenated blood from lungs to heart
Deoxygenated With the exception of the pulmonary vessels, veins carry deoxygenated blood; arteries carry oxygenated blood.