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← Wood Technology & Design 1-4

Circulatory System

Focus on human heart structure, double circulation, and blood components.

📘 Topic Summary

The circulatory system is a vital network of organs and vessels that transport blood throughout the body, supplying oxygen and nutrients to tissues and removing waste products.

📖 Glossary
  • Atrium: The upper chamber of the heart where blood returns from the body.
  • Ventricle: The lower chamber of the heart that pumps blood out to the body.
  • Arterial circulation: The pathway by which oxygenated blood is transported from the heart to the rest of the body.
  • Venous circulation: The pathway by which deoxygenated blood returns to the heart from the body.
⭐ Key Points
  • The human heart pumps around 2,000 gallons of blood daily.
  • Blood vessels are classified into arteries, veins, and capillaries based on their function and structure.
  • Oxygen-rich blood is transported to the lungs for carbon dioxide removal through the pulmonary circulation.
  • Deoxygenated blood returns from the body to the heart through the systemic circulation.
  • The circulatory system plays a crucial role in maintaining homeostasis, regulating body temperature, and facilitating nutrient delivery.
🔍 Subtopics
Human Heart Structure

The human heart is a muscular organ that pumps blood throughout the body. It has four chambers: the left and right atria, and the left and right ventricles. The atria receive blood returning to the heart, while the ventricles pump blood out of the heart. The septum, a thin wall of tissue, separates the left and right sides of the heart.

Double Circulation

The human circulatory system is characterized by double circulation, where deoxygenated blood returns to the heart through the superior and inferior vena cavae, while oxygenated blood from the lungs enters the heart through the pulmonary veins. The oxygen-rich blood then flows into the left ventricle, which pumps it out to the rest of the body via the aorta.

Blood Components

Human blood is composed of approximately 45% red blood cells, 55% plasma, and small amounts of white blood cells and platelets. Red blood cells carry oxygen from the lungs to the body's tissues, while plasma carries proteins, nutrients, hormones, and waste products. White blood cells help fight infections, and platelets aid in blood clotting.

Arterial Circulation

Arterial circulation begins with the aorta, which branches into smaller arteries that distribute oxygenated blood to the body's tissues. Arteries are thicker-walled than veins and have a higher pressure due to the heart's pumping action. The arterial system is responsible for delivering oxygen and nutrients to the body's cells.

Venous Circulation

Venous circulation begins with the venules, which merge into larger veins that return deoxygenated blood to the heart. Veins have thinner walls than arteries and a lower pressure due to the one-way flow of blood back to the heart. The venous system is responsible for returning oxygen-depleted blood from the body's tissues back to the heart.

🧠 Practice Questions

  1. What is the primary function of the atrium in the circulatory system?

  2. Which type of circulation is responsible for transporting oxygen-rich blood to the rest of the body?

  3. What is the approximate daily volume of blood pumped by the human heart?

  4. What is the primary function of capillaries in the circulatory system?

  5. What is the term for the pathway by which deoxygenated blood returns to the heart from the body?

  6. What is the function of the ventricles in the circulatory system?

  7. What is the term for the pathway by which oxygenated blood enters the heart from the lungs?

  8. What is the primary function of the aorta in the circulatory system?

  9. What is the term for the pathway by which oxygen-rich blood is transported to the rest of the body?

  10. What is the approximate percentage of red blood cells in human blood?

  1. Describe the pathway by which deoxygenated blood returns to the heart from the body. (2 marks)

  2. Explain how oxygen-rich blood is transported to the rest of the body. (2 marks)

  3. Describe the function of the atria in the circulatory system. (2 marks)

  4. Explain how the heart pumps blood throughout the body. (2 marks)

  5. Describe the role of capillaries in the circulatory system. (2 marks)

  1. Discuss the importance of the circulatory system in maintaining homeostasis and regulating body temperature. (20 marks) (20 marks)

  2. Describe the double circulation pathway and explain how it allows for efficient exchange of oxygen and nutrients with tissues. (20 marks) (20 marks)