IGCSE Biology: Chapter 9 - Transport in Animals

Introduction

• Overview of the circulatory system in animals.
• Circulatory system: blood vessels, pump, and valves ensure one-way blood flow.
• Summary of single and double circulatory systems.

Single Circulatory System (Fish)

• Fish have a single circulatory system.
• Heart structure: 2 chambers (Atrium and Ventricle).
• Blood passes through the heart once per circuit.
• Blood flow:
  • Deoxygenated blood from body -> Atrium -> Ventricle -> Gills (oxygenation) -> Body.
  • Gills: site of oxygen absorption.
  • Circulation types:
    • Gill circulation: blood to gills for oxygenation.
    • Systemic circulation: oxygenated blood to the rest of the body.

Double Circulatory System (Mammals)

• Mammals have a double circulatory system.
• Heart structure: 4 chambers (2 Atria, 2 Ventricles).
• Blood passes through the heart twice per circuit.
• Blood flow:
  • Deoxygenated blood enters right atrium via vena cava -> right ventricle -> pumped to lungs via pulmonary artery (oxygenation).
  • Oxygenated blood returns to left atrium via pulmonary vein -> left ventricle -> pumped to body via aorta.
• Circulation types:
  • Pulmonary circulation: right side of heart to lungs.
  • Systemic circulation: left side of heart to body.

Advantages of Double Circulation

• Larger body size requires more oxygen and glucose for respiration.
• More efficient delivery of oxygen and glucose.
• Maintains higher blood pressure compared to single circulation.

Structures of the Mammalian Heart

• Right Atrium: Receives deoxygenated blood via vena cava.
• Tricuspid Valve: Separates atrium and ventricle; prevents backflow.
• Right Ventricle: Pumps blood to lungs via pulmonary artery.
• Septum: Muscle wall separating the heart sides.
• Left Atrium: Receives oxygenated blood from lungs via pulmonary vein.
• Bicuspid Valve: Separates left atrium and ventricle; prevents backflow.
• Left Ventricle: Pumps oxygenated blood to the body via aorta.

Tips & Tricks

• Remember: Arteries carry blood away from the heart (A for Artery = A for Away).
• Coronary Arteries supply blood to heart muscle.
• Ventricles have thicker walls than Atria due to higher pressure needs.

Monitoring Heart Activity

• Can be monitored using:
  • ECG
  • Pulse rate
  • Stethoscope for valve sounds.

Effect of Physical Activity on Heart Rate

• Pulse rate increases during exercise due to higher energy needs.
• Oxygen and glucose demand rises; waste products must be removed faster.
• Recovery time noted after exercise.

Coronary Heart Disease (CHD)

• Caused by blockage of coronary arteries leading to oxygen starvation.
• Causes: Cholesterol buildup, unhealthy diet, lack of exercise, stress, smoking, genetics, age, and gender.
• Risk Factors: High cholesterol, sedentary lifestyle, stress, smoking, genetics.
• Prevention: Quit smoking, healthy diet, regular exercise.

Conclusion

• Summary of the importance of understanding the circulatory systems in animals for IGCSE.
• Encourage viewers to subscribe for more educational content.