Transport in Animals - Cambridge IGCSE Biology 0610 - Detailed Notes

9. Transport in Animals

9.1 Circulatory Systems

  • Definition: The circulatory system consists of blood vessels, a pump (the heart), and valves to ensure unidirectional flow of blood.

  • Single Circulation in Fish:

    • Blood flows through the heart once during a complete circuit: from heart to gills to body and back to heart.

  • Double Circulation in Mammals:

    • Blood passes through the heart twice during a complete circuit:

    • Systemic Circulation: Oxygenated blood is pumped from the left side of the heart to the body.

    • Pulmonary Circulation: Deoxygenated blood is taken from the right side of the heart to the lungs for oxygenation.

  • Advantages of Double Circulation:

    • Allows for higher efficiency and pressure when oxygenating blood.

/

9.2 Heart

  • Identification:

    • Structures of the Mammalian Heart: Muscular wall, septum, left and right ventricles, left and right atria, one-way valves, coronary arteries.

  • Blood Flow Direction:

    • Blood is pumped away from the heart through arteries and returns via veins.

  • Monitoring Heart Activity:

    • Methods include ECG (Electrocardiogram), pulse rate, and auscultation (listening for valve sounds).

  • Effect of Physical Activity:

    • Physical activity increases heart rate due to increased demand for oxygen.

  • Coronary Heart Disease:

    • Caused by blockage of coronary arteries. Risk factors include:

    • Poor diet

    • Sedentary lifestyle

    • High stress

    • Smoking

    • Genetic factors

    • Age

    • Sex.

  • Diet and Exercise:

    • Both play significant roles in reducing heart disease risk.

  • Valves:

    • Identification of atrioventricular and semilunar valves in the heart.

  • Muscle Wall Thickness:

    • Left ventricle has a thicker wall than the right due to higher pressure in systemic circulation.

    • Atria walls are thinner than ventricular walls due to lower pressure.

  • Septum Importance:

    • Separates oxygenated and deoxygenated blood, preventing mixing.

  • Heart Functioning:

    • Contraction of atrial and ventricular muscles is coordinated with valve action.

9.3 Blood Vessels

  • Structures:

    • Arteries: Thick walls, narrower lumen, no valves. High pressure blood transport.

    • Veins: Thinner walls, wider lumen, presence of valves to prevent backflow.

    • Capillaries: Single-cell-thick walls for efficient exchange of materials.

  • Capillary Functions:

    • Facilitate exchange of oxygen, nutrients, and waste at the cellular level.

  • Identification of Main Blood Vessels:

    • To and from the heart: Vena Cava, Aorta, Pulmonary Artery, Pulmonary Vein.

    • To and from the lungs: Pulmonary Artery, Pulmonary Vein.

    • To and from the kidney: Renal Artery, Renal Vein.

  • Relation of Structure to Function:

    • Arteries are built to withstand high pressure due to thick walls.

    • Veins have thinner walls and valves as they carry blood at lower pressure.

    • Capillary walls are thin to allow diffusion of materials.

  • Identification of Liver Blood Vessels:

    • Hepatic Artery, Hepatic Vein, Hepatic Portal Vein.

9.4 Blood

  • Components of Blood:

    • Red Blood Cells, White Blood Cells, Platelets, Plasma.

  • Functions:

    • Red Blood Cells: Transport oxygen via hemoglobin.

    • White Blood Cells: Immune response through phagocytosis and antibody production.

    • Platelets: Aid in clotting process (details not required).

    • Plasma: Transports cells, ions, nutrients, urea, hormones, and carbon dioxide.

  • Role of Clotting:

    • Prevents blood loss and pathogen entry.

  • Cell Identification:

    • Distinction between lymphocytes and phagocytes in diagrams and photomicrographs.

  • Process of Clotting:

    • Conversion of fibrinogen to fibrin forms a mesh to stop bleeding.