CAIE IGCSE Biology 0610 - Transport in Animals

Circulatory Systems

Overview

• A circulatory system consists of tubes (veins, capillaries, arteries), a pump (heart), and valves to ensure one-way blood flow.

Single Circulation System (Fish)

• Blood flows through the heart once per circuit (No Septum).
• Two heart chambers: Atrium and Ventricle.
• Blood absorbs oxygen in the gills at lower pressure.
• Blood released in body cells then returns to the heart.

Double Circulation System

• Four heart chambers.
• Blood passes through the heart twice per circuit.
• Oxygenated in lungs, then to the heart, to body, and back to the heart.
• Advantages: Higher blood flow rate to tissues, preventing mixing of oxygenated and deoxygenated blood.

Heart

• Right Atrium: Collects deoxygenated blood & pumps to the right ventricle.
• Right Ventricle: Pumps deoxygenated blood to lungs.
• Pulmonary Artery: Carries deoxygenated blood from right ventricle to lungs.
• Septum: Separates left & right sides; keeps deoxygenated and oxygenated blood separate.
• Pulmonary Vein: Carries oxygenated blood from lungs to left atrium.
• Left Atrium: Collects oxygenated blood, pumps to left ventricle.
• Left Ventricle: Pumps oxygenated blood to the body via aorta.
• Aorta: Carries oxygenated blood from left ventricle to body.
• Valves: Atrioventricular and semi-lunar valves prevent backflow.
• Muscle Wall Thickness: Atria < Right Ventricle < Left Ventricle.

Functioning of the Heart

• Deoxygenated blood enters right atrium via vena cava.
• Blood moves to right ventricle through atrioventricular valve.
• Ventricle contracts, blood moves to pulmonary artery through semilunar valve.
• Blood travels to lungs, oxygenated blood returns to left atrium via pulmonary vein.
• Moves to left ventricle, pumped into aorta and around the body.
• Semilunar valve in aorta prevents backflow.

Exercise on Heart Rate

• Monitored via ECG, pulse, stethoscope.
• Physical activity increases heart rate for better circulation of oxygen and glucose.

Coronary Heart Disease

• Coronary arteries are heart's blood supply.
• Blockage causes heart attack due to interrupted blood supply.
• Risk factors: diet, exercise, stress, smoking, genetics, age, sex.
• Prevention: no smoking, healthy diet, regular exercise.

Blood Vessels

Major Blood Vessels

• Heart: Vena Cava, Aorta, Pulmonary Arteries & Veins.
• Lungs: Pulmonary Arteries and Veins.
• Kidneys: Renal Arteries and Veins.
• Liver: Hepatic Artery, Veins, and Portal Vein.

Arterioles and Venules

• Arterioles: Connect arteries to capillaries.
• Venules: Connect capillaries to veins.

Blood

• Red Blood Cells: Biconcave, haemoglobin, oxygen transport.
• White Blood Cells: Phagocytosis, antibody production.
• Platelets: Blood clotting.
• Plasma: Transports cells, ions, nutrients, hormones.

White Blood Cells

• Antigens: Protein/carbohydrate on pathogens.
• Antibodies: Y-shaped proteins marking pathogens for destruction.

Blood Clotting

• Reduces blood loss, keeps pathogens out.
• Fibrinogen converts to fibrin, traps blood cells forming a scab.