Transport in animals

• Circulatory system


  A system of blood vessels with a pump and valves to ensure one-way flow of blood
• Circulatory system


  1. Flow of oxygenated blood

  2. Flow of deoxygenated blood
• Circulatory system of fish

  • Two-chambered heart
  • Single circulation
• Circulatory system of mammals

  • Four-chambered heart
  • Double circulation
• Circulatory system of mammals

  1. Right side of heart receives deoxygenated blood from body and pumps to lungs (pulmonary circulation)

  2. Left side of heart receives oxygenated blood from lungs and pumps to body (systemic circulation)
• For every one circuit of the body, the blood passes through the heart once in fish
• For every one circuit of the body, the blood passes through the heart twice in mammals
• Advantages of Double Circulation

  • Blood travelling through the small capillaries in the lungs loses a lot of pressure that was given to it by the pumping of the heart, meaning it cannot travel as fast
  • By returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body, meaning cells can be supplied with the oxygen and glucose they need for respiration faster and more frequently
• Mammalian Heart


  The heart is labelled as if it was in the chest so what is your left on a diagram is actually the right hand side and vice versa
• Blood flow in the heart

  1. Right side of the heart receives deoxygenated blood from the body and pumps it to the lungs

  2. Left side of the heart receives oxygenated blood from the lungs and pumps it to the body

  3. Blood is pumped towards the heart in veins and away from the heart in arteries

  4. The two sides of the heart are separated by a muscle wall called the septum

  5. The heart is made of muscle tissue which are supplied with blood by the coronary arteries
• Monitoring heart activity


  • Heart activity can be monitored by using an ECG, measuring pulse rate or listening to the sounds of valves closing using a stethoscope
  • Heart rate (and pulse rate) is measured in beats per minute (bpm)
• Investigating effect of exercise on heart rate

  1. Record the pulse rate at rest for a minute

  2. Immediately after they do some exercise, record the pulse rate every minute until it returns to the resting rate

  3. This experiment will show that during exercise the heart rate increases and may take several minutes to return to normal
• Increased physical activity results in an increased heart rate and breathing rate
• Heart rate remains high for a period of time after physical has stopped, there is a gradual return to resting heart rate
• Coronary Heart Disease


  • The heart is made of muscle cells that need their own supply of blood to deliver oxygen, glucose and other nutrients and remove carbon dioxide and other waste products
  • The blood is supplied by the coronary arteries
  • If a coronary artery becomes partially or completely blocked by fatty deposits called 'plaques' (mainly formed from cholesterol), the arteries are not as elastic as they should be and therefore cannot
• Coronary artery


  • Stretch to accommodate the blood which is being forced through them
  • Partial blockage creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
  • Complete blockage means cells in that area of the heart will not be able to respire and can no longer contract, leading to a heart attack
• A diet too high in saturated fat and cholesterol can lead to coronary heart disease
• Risk factors for coronary heart disease

  • Poor diet
  • Stress
  • Smoking
  • Genetic predisposition
  • Age
  • Gender
• Poor diet


  Eating more saturated fat increases cholesterol levels, increasing the chance of the buildup of fatty plaques
• Stress


  When under stress, hormones produced can increase blood pressure, increasing the chance of a blockage in the coronary arteries
• Smoking


  Nicotine in cigarettes will cause blood vessels to become narrower, increasing blood pressure which will cause the buildup of fat globules. If this occurs in the coronary artery, this will cause coronary heart disease
• Genetic predisposition


  Studies show that people with a history of coronary heart disease in their family are more likely to develop it themselves, suggesting it partly has a genetic basis
• Age


  The risk of developing coronary heart disease increases as you get older
• Gender


  Males are more likely to develop coronary heart disease than females
• Ways to reduce the risks of developing coronary heart disease

  • Quit smoking
  • Diet - reduce animal fats and eat more fruits and vegetables - this will reduce cholesterol levels in the blood and help with weight loss if overweight
  • Exercise regularly - again, this will help with weight loss, decrease blood pressure and cholesterol levels and help reduce stress
• Ventricles


  • Have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate a higher pressure
  • The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs
• Septum


  Separates the two sides of the heart and so prevents mixing of oxygenated and deoxygenated blood
• Atrioventricular valves


  Separate the atria from the ventricles
• Tricuspid valve


  The valve on the right side of the heart
• Bicuspid valve


  The valve on the left side of the heart
• Semilunar valves


  • Found in the two blood arteries that come out of the top of the heart
  • They are the only two arteries in the body that contain valves
  • They open when the ventricles contract so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart
• The basic function of all valves is to prevent blood from flowing backwards
• Functioning of the Heart

  1. Deoxygenated blood flows into right atrium via vena cava

  2. Blood pushed through tricuspid valve into right ventricle

  3. Blood pushed into pulmonary artery through semilunar valve

  4. Blood travels to lungs and through capillaries for gas exchange

  5. Oxygenated blood returns to left atrium via pulmonary vein

  6. Blood passes through bicuspid valve into left ventricle

  7. Blood pushed forcefully into aorta through semilunar valve
• Physical activity increases


  Heart rate increases
• Arteries


  • Carry blood at high pressure away from the heart
  • Carry oxygenated blood (other than pulmonary artery)
  • Have thick muscular walls with elastic fibres
  • Have narrow lumen
  • Speed of flow is fast
• Veins


  • Carry blood at low pressure towards the heart
  • Carry deoxygenated blood (other than pulmonary vein)
  • Have thin walls
  • Have large lumen
  • Contain valves
  • Speed of flow is slow
• Capillaries


  • Carry blood at low pressure within tissues
  • Carry both oxygenated and deoxygenated blood
  • Have walls that are one cell thick
  • Have 'leaky' walls
  • Speed of flow is slow
• Arteries narrow to arterioles and then capillaries as they pass through organs
• Capillaries widen to venules and finally veins as they move away from organs
• Veins carry blood back towards the heart