The Heart and Circulatory System - GCSE Combined Science

Overview

• The heart is a part of the double circulatory system.
• Blood is pumped away from the heart at high pressure in arteries and returns at low pressure in veins.
• Humans have a double circulatory system which involves blood passing through the heart twice per body circulation.

The Heart

• Unidirectional Pump: The heart functions as a unidirectional pump with valves to prevent backflow.
• Right Side: Pumps deoxygenated blood (low oxygen, high carbon dioxide) to the lungs.
• Left Side: Pumps oxygenated blood (high oxygen, low carbon dioxide) to the body.

Flow of Blood Through the Heart

1. Deoxygenated blood enters the right atrium from the vena cava.
2. Blood moves into the right ventricle.
3. Blood is pumped into the pulmonary artery.
4. Pulmonary artery carries blood to the lungs to be oxygenated.
5. Oxygenated blood returns via the pulmonary vein.
6. Blood enters the left atrium.
7. Blood moves into the left ventricle.
8. Blood is pumped into the aorta, supplying the body.

Heart Structure

• Atrial Walls: Thinner than ventricular walls.
• Ventricular Walls: Thicker as they pump blood further.
  • Left ventricle wall is thicker than right as it pumps blood throughout the body.

Key Blood Vessels and Their Functions

• Vena Cava: Carries deoxygenated blood to the heart.
• Pulmonary Artery: Carries deoxygenated blood to the lungs.
• Pulmonary Vein: Carries oxygenated blood to the heart.
• Aorta: Carries oxygenated blood to the body.
• Hepatic Artery: Supplies the liver with oxygenated blood.
• Hepatic Vein: Returns deoxygenated blood (with digested nutrients) to the heart.
• Hepatic Portal Vein: Carries nutrients from the small intestine to the liver.
• Renal Artery: Supplies kidneys with oxygenated blood (rich in urea).
• Renal Vein: Returns deoxygenated blood (low in urea) to the heart.

Role of Oxygen and Glucose

• Used for respiration in body cells.
• Coronary arteries supply heart muscle with necessary oxygen and glucose for respiration.

Visual Aids

• Images illustrating heart cross-section and double circulatory system were provided.