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  • Blood transports substances through the circulatory system.
  • Blood contains red blood cells, which take oxygen from the lungs to the body, they hold haemoglobin which binds to oxygen and have a biconcave shape so a large surface area.
  • Blood contains plasma which carries nutrients, antibodies, hormones and waste.
  • Blood contains white blood cells which help fight infection.
  • Blood contains platelets which help clot wounds.
  • We have a double circulatory system with a circuit that pumps deoxygenated blood to the lungs and back to the heart. The second circuit pumps oxygenated blood to the body where it gives up oxygen at body cells and returns deoxygenated blood to the heart.
  • Right atrium gets deoxygenated blood from body through vena cava, which goes to right ventricle to pump to lungs through pulmonary artery.
  • Left atrium gets oxygenated blood from lungs through pulmonary vein, which then goes to left ventricle to pump to whole body through the aorta.
  • Valves prevent backflow of blood, two coronary arteries give heart muscle cells blood and left ventricle wall is thicker than right as it pumps blood all around body. Atria have thinner walls as only pump blood to ventricle.


  • Arteries branch into capillaries and have permeable walls for diffusion of substances.
  • When blood goes through capillary beds, small molecules are forced out of capillariesto make tissue fluid. Substances diffuse out of tissue fluid into the cells.
  • Waste diffuses into tissue fluid, then into capillaries. 
  • A skeleton is needed for support, movement and protection of vital organs.
  • Some animals are vertebrates such as fish and birds (endoskeleton), but some have outside skeletons such as insects (exoskeleton).
  • Ligaments hold bones together and have a high tensile strength and are elastic so they can stabalise joints and allow movement.
  • Ends of bones covered in cartilage which can be slightly compressed so it acts as a shock absorber.
  • Membranes can release synovial fluid to lubricate joints for easier movement.
  • Tendons attach muscles to bones, can withstand tension.
  • Muscles move bones at a joint by contracting and tendons can't stretch so when muscles contract, then tendon pulls on the bone and transmists a force from the muscle to the bone.
  • Muscles can't push so they come in antagonistic pairs.
  • Muscles contract when proteins in their cells react together. This pulls the two ends of the muscle closer together. Muscles can relax, which allows them to be pulled longer.
  • When the bicep contracts, the tricep relaxes. When the tricep contracts, the bicep relaxes.


  • Exercise increases fitness and should be done in a structured way, e.g. a regime.
  • Fitness practitioners need to know information such as any health problems, current medication, previous fitness treatements, other lifestyle factors, family medical history or physical activity. 
  • Heart rate/blood pressure resting level is when you aren't exercising. When you exercise they will increase. 
  • The time it takes for them to return to resting level after exercise is the recovery period, a shorter recovery


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