Transport in Animals IGCSE
IGCSE (Year 10โ11) ๐ซ Physiology & Health Heart, blood vessels, blood components, double circulation.
๐ซ The Heart and Double Circulation
Mammals have a double circulatory system: pulmonary (heart โ lungs โ heart) and systemic (heart โ body โ heart).
- Right atrium โ receives deoxygenated blood from body (via vena cava)
- Right ventricle โ pumps blood to lungs (pulmonary artery)
- Left atrium โ receives oxygenated blood from lungs (pulmonary vein)
- Left ventricle โ pumps blood to body (aorta); thicker walls than right ventricle
- Valves โ atrioventricular (AV) and semilunar (SL) valves prevent backflow
Cardiac Output
$$\text{Cardiac output (dm}^3\text{/min)} = \text{Stroke volume (dm}^3\text{)} \times \text{Heart rate (beats/min)}$$๐ซ Blood Vessels and Blood
| Vessel | Direction | Features |
|---|---|---|
| Artery | Away from heart | Thick muscle + elastic walls; high pressure; no valves |
| Vein | Towards heart | Thinner walls; low pressure; has valves (prevent backflow) |
| Capillary | Between arteries and veins | One cell thick (1 ฮผm); vast surface area; allows exchange |
| Component | Function |
|---|---|
| Red blood cells (erythrocytes) | Carry Oโ as oxyhaemoglobin; biconcave disc, no nucleus |
| White blood cells (leucocytes) | Phagocytes (engulf pathogens) + Lymphocytes (antibodies) |
| Platelets (thrombocytes) | Blood clotting (fibrin mesh formation) |
| Plasma | Transport of glucose, COโ, urea, hormones, heat |
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Interactive Demo โ Transport in Animals IGCSE
Cardiac Output Calculator
Cardiac Output = Stroke Volume ร Heart Rate