Circulatory System and Human Heart

Circulatory System

• The circulatory system transports materials like nutrients and oxygen throughout the body.
• This system needs a pump (the heart) to work effectively.

The Human Heart

• The heart has four chambers: two atria (left and right) and two ventricles (left and right).
• The atria are the upper chambers and the ventricles are the lower chambers.
• The left side of the heart is thicker than the right side because it pumps oxygen-rich blood throughout the body.
• The right side of the heart pumps blood to the lungs.
• Blood flows in one direction through the heart.

Heart Valves

• The heart has four valves that act like one-way doors to keep blood flowing in the correct direction.
• The tricuspid valve is between the right atrium and the right ventricle.
• The bicuspid valve is between the left atrium and the left ventricle.
• The pulmonary valve is between the right ventricle and the pulmonary artery.
• The aortic valve is between the left ventricle and the aorta.
• The valves prevent blood from flowing backward.

Blood Flow Through The Heart

• Blood flows from the atria into the ventricles.
• Then, the ventricles pump blood to the lungs or the rest of the body.
• The heart's rhythmic contractions (heartbeat) are due to cardiac muscle tissue.
• The atria and ventricles contract at specific times (in coordination).

Oxygen-Rich and Oxygen-Poor Blood

• The left side of the heart has oxygen-rich blood; shown in red.

• The right side of the heart has oxygen-poor blood; shown in blue.

• A septum separates the right and left sides of the heart, preventing mixing of oxygen-rich and oxygen-poor blood.