- What is meant by a double circulatory system?
- two circuits joined together
- right: pumps deoxygenated blood to lungs to get oxygen, then returns to the heart
- left: pumps oxygenated blood round the body to body cells then deoxygenated blood returns back to heart
- What does blood do?
-blood carries glucose molecules and oxygen to the muscles, and waste products such as carbon dioxide away from muscles
- What are the components of the blood and their functions?
- red blood cells – transport oxygen
- white blood cells – fighting infections
- platelets – blood clotting at injury sites
- plasma – transporting nutrients (e.g. glucose and amino acids), antibodies, hormones and waste (carbon dioxide and urea)
- How are red blood cells adapted to their function?
- packed with haemoglobin (to bind oxygen)
- no nucleus (more space for haemoglobin)
- biconcave shape (increased surface area for oxygen exchange)
- What are the main structures and blood vessels of the heart?
Left and right atria and ventricles, vena cava, aorta, pulmonary vein, pulmonary artery, coronary arteries and valves
- What is the function of the (2) CORNARY ARTERIES?
-supply heart muscle cells with blood
- What is the function of the VALVES?
-in heart and veins to prevent the backflow of blood
- What are the properties of the different ventricles and atria?
- left ventricles thicker than the right: has to pump blood all the way round body, not just to lungs
- atria have thinner walls than ventricles: only have to pump blood to ventricles
- What are capillaries?
- tiny blood vessels that branch from arteries
- they have permeable walls so substances can diffuse through
- What are capillary beds?
-networks of capillaries in tissue
- What happens when blood passes through capillary beds?
- small molecules e.g. water, glucose, oxygen are forced out the capillaries to form tissue fluid that surrounds the cells
- waste chemicals e.g. carbon dioxide and urea diffuse from cells to tissue fluid to capillaries
- What is the purpose of tissue fluid?
-it allows cells to get substances they need and get rid of waste without a capillary supplying every cell
- What are examples of waste products in cells?
-carbon dioxide, urea
- What does tissue fluid do (definition)?
-tissue fluid is formed in capillary beds and that it assists the exchange of chemicals by diffusion between capillaries and tissues, to include oxygen, carbon dioxide, glucose and urea
- What is the flow of the heart?
Body → vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta → body