Animal Transport Systems Mr G Davidson National 5 Animal Transport Systems

Mammalian Circulation Because large animals have a small surface area:volume ratio, they need to have areas in the body where materials can be absorbed. This happens in places like the lungs and small intestine. Once these materials have been absorbed, they have to be distributed throughout the cells of the body, and this is achieved through the circulatory system. Thursday, 20 September 2018 Mr G Davidson

Mammalian Circulatory System Circulation is brought about by a pump called the heart and vessels called arteries, veins and capillaries. The heart has four chambers split between two sides. Each side has a ventricle and an atrium. Thursday, 20 September 2018 Mr G Davidson

Mammalian Heart Left Atrium Right Atrium Left Ventricle Right Ventricle Thursday, 20 September 2018 Mr G Davidson

Circulation Pulmonary vein Pulmonary artery Aorta Vena Cava Deoxygenated blood Oxygenated blood Thursday, 20 September 2018 Mr G Davidson

Blood Flow As blood travels around the body, it has to pass through the heart twice. It is returned from the body in the vena cava into the right atrium. The right atrium pushes the blood down into the right ventricle. Thursday, 20 September 2018 Mr G Davidson

Blood Flow When the right ventricle contracts, the blood leaves in the pulmonary artery and is carried to the lungs. While in the lungs, the blood becomes oxygenated (picks up a fresh supply of oxygen). Thursday, 20 September 2018 Mr G Davidson

Blood Flow The blood now returns to the heart in the pulmonary vein into the left atrium. When the left atrium contracts the blood is pushed down into the left ventricle. Thursday, 20 September 2018 Mr G Davidson

Blood Flow When the left ventricle contracts the blood is forced out into the aorta, which is the biggest artery in the body, and it is now sent to all parts of the body to deliver this fresh oxygen. As the oxygen is used up by the cells of the body, the blood becomes deoxygenated and is returned to the heart in the vena cava. And so the cycle continues. Thursday, 20 September 2018 Mr G Davidson

Structure of the Heart The wall of the left ventricle is much thicker than the wall of the right ventricle. This is because the right ventricle only has to pump the blood as far as the lungs which are close to the heart. The left ventricle, however, has to pump blood a lot farther and therefore needs a greater pressure to do this, hence the thicker walls. Thursday, 20 September 2018 Mr G Davidson

Structure of the Heart The heart also contains four valves. Two of them are to be found between the atria and the ventricles. These prevent blood from flowing backwards into the atria when the ventricles contract. Thursday, 20 September 2018 Mr G Davidson

Structure of the Heart The other two valves open when the ventricles contract allowing blood out. They then close to prevent the blood flowing backwards into the ventricles. Thursday, 20 September 2018 Mr G Davidson

Blood Vessels Blood is carried away from the heart in arteries. These have thick muscular walls in order to cope with the high pressure of the blood as it leaves the heart. The pulmonary artery is the only artery in the body which doesn’t carry oxygenated blood. Thursday, 20 September 2018 Mr G Davidson

Blood Vessels As blood is forced through the arteries, you can feel each heart beat as your pulse. Veins carry blood back to the heart. They have thinner walls and lots of valves along their length to prevent a backflow of blood. Thursday, 20 September 2018 Mr G Davidson

Blood Vessels Capillaries are what the blood passes through between the arteries and veins. They are tiny blood vessels, often only one cell thick, which allow the exchange of materials out of, and into, the blood. We have approximately 50,000 miles of capillaries in our body. Thursday, 20 September 2018 Mr G Davidson

Circulatory System Thursday, 20 September 2018 Mr G Davidson

Coronary Artery Although the heart is responsible for pumping blood round the body, it must also have its own blood supply. This is called the coronary artery, and it supplies the heart with its own oxygenated blood. If the coronary artery becomes blocked in any way, the person suffers a heart attack. Thursday, 20 September 2018 Mr G Davidson

Coronary Artery Aorta Coronary artery Thursday, 20 September 2018 Mr G Davidson

Blood Blood is composed of red blood cells, white blood cells, platelets and plasma. The cells and the platelets are carried in the plasma which is the fluid part of the blood. White cells help our body to fight off disease. Platelets are used to help the blood to clot at a cut. Thursday, 20 September 2018 Mr G Davidson

Blood Red blood cells are responsible for carrying oxygen to all body cells. They are biconcave in shape which gives them a large surface area. This allows the red pigment, called haemoglobin, to combine with oxygen and become oxyhaemoglobin. Thursday, 20 September 2018 Mr G Davidson

Red Blood Cells Cross section Biconcave Thursday, 20 September 2018 Mr G Davidson

Blood This happens in the blood capillaries in the lungs. When the blood reaches the body cells which are respiring, the oxyhaemoglobin releases the oxygen and turns back into haemoglobin. The blood is then returned to the lungs where fresh oxygen will convert it back to oxyhaemoglobin. Thursday, 20 September 2018 Mr G Davidson

Haemoglobin Oxygen In lungs Haemoglobin Oxyhaemoglobin Haemoglobin In cells Thursday, 20 September 2018 Mr G Davidson

Gas Exchange Mammals exchange gases with the air through the lungs. Air enters the body through the nose or mouth and passes down the trachea (windpipe) towards the lungs. The trachea is kept open at all times by rings of cartilage. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange At each lung the trachea splits into the left and right bronchus, one going to each lung. The bronchi then further divide into smaller branches called bronchioles. The bronchioles eventually end in small air sacs called alveoli. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange Thursday, 20 September 2018 Mr G Davidson

Gas Exchange The air passages are lined with 2 types of cell. Ciliated cells which have small hairs on their surface called cilia. Mucus secreting cells which release a sticky fluid called mucus. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange As we breathe air in, the air contains dust and microbes which sticks to the mucus. The cilia then sweep the mucus containing the dirt and microbes upwards and into the mouth where it is swallowed. Thursday, 20 September 2018 Mr G Davidson

Trachea Mucus-secreting Cilia cell Mucus Thursday, 20 September 2018 Mr G Davidson

Gas Exchange When the air reaches the alveoli, gases are exchanged between the lungs and the blood. The alveoli provide a huge surface area to do this because there are so many of them. Thursday, 20 September 2018 Mr G Davidson

Alveolus Bronchiole Blood capillaries Alveolus Thursday, 20 September 2018 Mr G Davidson

Gas Exchange Each alveolus is surrounded by a dense network of blood capillaries. The lining of the alveolus is moist and this allows the gases to dissolve before diffusing. The lining of the alveolus is also very thin which allows a rapid movement of the gases. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange in the Alveolus Thursday, 20 September 2018 Mr G Davidson

Gas Exchange Blood entering the capillaries at the alveoli has been pumped there by the heart in the pulmonary artery. This blood is deoxygenated. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange At the lining of the alveoli the carbon dioxide diffuses out of the blood and into the alveolus. At the same time the oxygen in the alveoli diffuses into the blood. This oxygenates the blood before it is returned to the heart in the pulmonary vein. Thursday, 20 September 2018 Mr G Davidson

Gas Exchange The lungs are efficient organs of gas exchange because of the following properties: Large surface area Thin walls Moist walls Good blood supply Thursday, 20 September 2018 Mr G Davidson

Transport of Food Food is taken into the body through the digestive system. Most of the food we eat is insoluble. Our digestive system is responsible for making this insoluble food soluble so that it can be transported in the blood. Thursday, 20 September 2018 Mr G Davidson

Digestive System Salivary Glands Mouth Oesophagus Liver Gall Bladder Stomach Pancreas Large Intestine Small Intestine Anus Thursday, 20 September 2018 Mr G Davidson

Digestive System As food passes through the digestive system, it is broken down by chemicals called enzymes. Enzymes are made in the salivary glands, pancreas, stomach and small intestine. Food is moved through the oesophagus by a process called peristalsis. Thursday, 20 September 2018 Mr G Davidson

Peristalsis Thursday, 20 September 2018 Mr G Davidson

Peristalsis The muscular wall of the oesophagus contracts just behind the food. The muscular wall in front of the food relaxes to allow the food through. It’s a bit like pushing a tennis ball through a sock. Peristalsis is also responsible for moving food through other parts of the gut. Thursday, 20 September 2018 Mr G Davidson

Small Intestine As the food passes through the digestive system, more and more of it becomes soluble caused by the enzymes. Carbohydrates are broken down to glucose. Proteins are broken down to amino acids. Fats are broken down to fatty acids & glycerol. These soluble products now need to enter the bloodstream to be transported around the body. Thursday, 20 September 2018 Mr G Davidson

Small Intestine The products of digestion are absorbed by the blood in the small intestine. The small intestine has a very large surface area to do this. It’s surface area is hugely increased by the presence of millions of tiny projections called villi. (villus singular) Thursday, 20 September 2018 Mr G Davidson

Villus Thin epithelium (makes absorption easier) Blood capillary (absorbs glucose and amino acids) Lacteal (absorbs products of fat digestion) Thursday, 20 September 2018 Mr G Davidson

Villus The villi are ideally suited to absorption because: They present a large surface area. They are only one cell thick which means materials can pass through easily. They contain a dense network of blood capillaries to transport the soluble glucose and amino acids away. They contain lacteals which transport the products of fat digestion away into the lymphatic system. Thursday, 20 September 2018 Mr G Davidson