Chapter 9: Transport in animals Flashcards
Define ‘circulatory system’
A system of blood vessels with a pump and valves to ensure one-way flow of blood
Describe the single circulation of a fish
Oxygen diffuses into the blood from the gills and from the blood to the body cells. Blood passes through the heart only once on one complete circuit
Describe the double circulation of a mammal
Blood passes through the heart twice on one complete circuit. Oxygen diffuses into the blood from the lungs and passes through the left side of the heart before diffusing from the blood to the body cells. Deoxygenated blood passes through the right side of the heart before returning to the lungs
What are the advantages of double circulation?
Low-pressure blood is delivered back to the heart, which raises its pressure, and allows it to travel to the rest of the body cells faster than a fish. This means oxygen for respiration is delivered faster in a mammal
How thick are the ventricles’ muscle walls compared to the atria’s, and why?
The ventricles have thicker muscle walls than the atria as they receive blood from the atria, and they have to pump blood out of the heart and all around the body
How thick are the muscle walls of the left and right ventricles, and why?
The left ventricle has a thicker muscle wall than the right ventricle, as the left ventricle has to pump blood to the rest of the body, while the right ventricle pumps blood to the lungs, which are close to the heart.
What is the importance of the septum?
Separates oxygenated and deoxygenated blood, and prevents backflow of blood into the heart chambers
How does the heart function?
Blood flows into the atria, which contract and push blood into the ventricles. The atrioventricular valves close to prevent backflow, and the ventricles contract to pump blood out of the heart, leading to the semilunar valves closing.
What are the functions of arteries and veins?
Arteries carry blood away from the heart, veins carry blood towards the heart
How can the activity of the heart be monitored?
ECG, taking the pulse rate, listening to the ‘lub-DUB’ sound of the valves closing
How do you investigate the effect of physical activity on the heart rate?
Measure someone’s pulse rate while sitting still and record the values. Then ask them to do exercise, such as running on the spot for a minute, and take their pulse rate after they stop. Do this every 2 minutes until pulse rate returns to normal
Explain the effect of physical activity on the heart rate
Heart rate increases during physical activity to increase blood flow to the working muscles to provide them with enough nutrients and oxygen for increased respiration. After exercise, the heart continues to beat faster to deliver extra oxygen to the muscle cells to pay off the oxygen debt accumulated when oxygen levels are not high enough to support aerobic respiration
Define ‘coronary heart disease’
A disease that is caused by the blockage of the coronary arteries
What are the possible risk factors for CHD?
Diet, lack of exercise, stress, smoking, genetic predisposition, age and sex
What are the roles of diet and exercise in reducing the risk of coronary heart disease?
A diet high in saturated fats leads to an increase in cholesterol in the bloodstream, leading to an increased risk of CHD. Regular exercise keeps you fit, prevents excessive weight gain, and decreases blood pressure
What are the structures of arteries, veins and capillaries?
Arteries: thick walls to carry high-pressure blood away from the heart, small lumen
Veins: thin walls that carry low-pressure blood to the heart, large lumen, valves present to prevent backflow
Capillaries: walls are 1 cell thick, very small lumen
What are the functions of capillaries, and how is their structure related?
Take nutrients, oxygen, and other materials to all the cells in the body. Their walls are 1 cell thick, so substances can get in and out easily, increases surface area for diffusion
What are the blood vessels which carry blood to and from the liver and kidneys?
Liver: hepatic artery (from heart to liver), hepatic vein (from liver to heart), hepatic portal vein (from digestive system to liver)
Kidneys: renal artery (heart to kidneys), renal vein (kidneys to heart)
What are the components of blood?
Red blood cells, white blood cells, platelets and plasma
What are the functions of red blood cells, and how is their structure related?
Contains haemoglobin, which carries oxygen. Red blood cells do not possess a nucleus or mitochondria, creating more space for packing in haemoglobin molecules. Shape is biconcave, creating a larger surface area to volume ratio, speeding up diffusion rate
What are the functions of lymphocytes and phagocytes?
Lymphocytes: produce antibodies
Phagocytes: engulf pathogens by phagocytosis
What are the functions of platelets, blood clotting and plasma?
Platelets: blood clotting to stop blood loss, and pathogens from getting into the body through breaks in the skin
Plasma: transports blood cells, ions,
nutrients, urea, hormones and carbon dioxide
What is the process of blood clotting?
Fibrinogen, present in blood plasma, is changed into fibrin by a substance released by platelets. This forms fibres, which pile up on top of each other to make a mesh-like structure that seals the wound. Platelets stick together to form clumps, and the fibres, the trapped red blood cells, and the clumps of platelets form a blood clot.
