Transport Systems in Mammals


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This presentation is a combination of different slides which I re-purposed. I included a reference of all the slides I used at the end of my presentation.

Transport Systems in Mammals

  1. 1. Transport Systems in Mammals Re-purposed by Trischa Pretorius
  2. 2. Why are Transport Systems Needed? • Many invertebrates rely on diffusion to supply its cells with oxygen. However diffusion is only efficient over short distances. • In large animals such as humans more oxygen are required for respiration in our muscles and so we need a more effective way of delivering large quantities of oxygen quickly – hence our circulatory system.
  3. 3. The Types of Circulatory System Open Circulatory system (as seen in insects) Closed circulatory system (as seen in worms)
  4. 4. Open Circulatory System • In an open circulatory system the blood enters and circulates in the interstitial spaces (spaces between the tissues). • The exchange of materials between the cells and the blood is done directly. • There are few blood vessels but they are not extensive. • The blood vessels are open-ended as they open into the common cavities called the haemocoel.
  5. 5. Closed Circulatory System • In a closed circulatory system the blood always remains inside the blood vessels and never comes in direct contact with the cells. • The materials enter and exit the blood vessels through the walls. • The blood flows in the blood vessels under high pressure such that it reaches all the parts of the body in good time. • The blood vessels are branched into fine capillaries which are actually involved in the exchange of materials.
  6. 6. Double Circulatory System • In a double circulatory system, blood travels in two circuits around the body. • Pulmonary circuit: Deoxygenated blood travels from the heart to the lungs where it gains oxygen and returns to the heart. • Systemic circuit: Oxygenated blood travels from the heart to all parts of the body and back to the heart
  7. 7. Blood passes through heart TWICE per complete circuit
  8. 8. • Blood returning to the heart is low in oxygen and high in carbon dioxide. • This blood is said to be deoxygenated. • Blood leaving the heart is high in oxygen and low in carbon dioxide • This blood is said to be oxygenated. Oxygenated and deoxygenated blood
  9. 9. Different types of blood vessels • Arteries • Veins • Capillaries
  10. 10. Arteries • Arteries carries blood away from the heart, and towards organs. • Blood travels at high pressure and is usually oxygenated. • The artery has thick muscular walls to withstand the high pressure. • Some major arteries are:  Aorta  Pulmonary Artery  Hepatic Artery  Renal Artery
  11. 11. Veins • Veins take blood to the heart and away from organs. • Blood travels at low pressure therefore veins have valves to prevent blood going backwards - if the blood goes backwards (i.e. towards the valves) this will cause them to close and thus preventing further movement. • The blood inside veins is usually deoxygenated.
  12. 12. Veins • Some major veins are:  Vena Cava  Pulmonary Artery  Hepatic Portal Vein  Renal Vein
  13. 13. Capillaries • Capillaries are microscopic vessels that connect arterioles to venules. • Walls are only 1 cell thick and allow substances to be exchanged between blood and body cells.
  14. 14. The Heart and Associated Blood Vessels • The heart consists of 4 chambers. • The upper chambers receive blood and are called atria. • The lower chambers pump blood out of the heart and are called ventricles. • There are valves situated between the chambers and at the points where blood leaves the heart. • Valves are present to ensure that blood only travels in one direction.
  15. 15. The Heart and Associated Blood Vessels • Between the atria and the ventricles are atrioventricular valves, which prevent back- flow of blood from the ventricles to the atria. • The left valve has two flaps and is called the bicuspid (or mitral) valve, while the right valve has 3 flaps and is called the tricuspid valve. • The valves are held in place by valve tendons (“heart strings”) attached to papillary muscles, which contract at the same time as the ventricles, holding the valves closed.
  16. 16. The Heart and Associated Blood Vessels There are also two semi-lunar valves in the arteries (the only examples of valves in arteries) called the pulmonary and aortic valves. These valves prevent the blood flowing back to the ventricles.
  17. 17. When the blood reaches the alveoli, oxygen diffuses into the blood and carbon dioxide diffuses into the alveoli. 1 6 5 4 3 2 7 1 2 3 4 5 6 7 Blood travels in the pulmonary artery to the lungs. The right ventricle contracts and forces blood through the pulmonary valve. Blood enters the right ventricle. The right atrium contracts and forces blood through the tricuspid valve. Blood enters the right atrium. Blood returns back to the heart through the vena cava. The Heart and Associated Blood Vessels
  18. 18. 8 13 12 11 10 9 14 1 2 3 4 5 6 7 When the blood reaches the body cells, oxygen diffuses into the cells and carbon dioxide diffuses into the blood. Blood travels in the aorta to the body. The left ventricle contracts and forces blood through the aortic valve. Blood enters the left ventricle. The left atrium contracts and forces blood through the bicuspid valve. Blood enters the left atrium. Blood returns back to the heart through the pulmonary vein. 8 9 10 11 12 13 14 The Heart and Associated Blood Vessels
  19. 19. The External Structure of the Human Heart
  20. 20. The Internal Structure of the Human Heart (Bicuspid valve)
  21. 21. Blood Flow through the Heart
  22. 22. Cardiac Cycle • There is a sequence of events at each heartbeat called the cardiac cycle. • There are two phases – contraction (systole) and relaxation (diastole). Blood enters the atria from the veins. • Contraction of the muscles of the atrial wall forces blood into the ventricles. • Blood is pumped out of the heart by contraction of the ventricle muscles.
  23. 23. Cardiac Cycle • Contraction of the atrial muscles is called atrial systole. • Contraction of the ventricular muscles is called ventricular systole. • Relaxation of the heart muscle is called diastole. • The pulse is a pressure wave caused by contraction of the left ventricle.
  24. 24. Cardiac Cycle
  25. 25. Cardiac Cycle: Electrocardiogram (ECG) Electrodes are placed on the skin over opposite sides of the heart, and the electrical potentials generated recorded with time. The result is an ECG. P wave = electrical activity during atrial systole QRS complex = electrical activity during ventricular systole T wave = ventricular repolaristion (recovery of ventricular walls) Q-T interval – contraction time (ventricles contracting) T-P interval – filling time – ventricles relaxed and filling with blood
  26. 26. 3) The impulse is passed from the AV node down the bundle of His. The bundle of His fibres as inside the septum. They take the electrical impulse down to the apex of the heart. The bundle of His fibres are insulated so the ventricles don’t start to contract. 4) The Purkinje fibres make the left and right ventricles contract. The electrical impulses travel UP the Purkinje fibres from the apex of the heart. This makes the ventricles contract from the apex of the heart. This squeezes blood UP and out of the heart. 2) The electrical impulse reaches the AV node. The AV node delays the electrical impulse. This is to give enough time for all of the blood to move from the atria into the ventricles. 1) The SA Node = ‘Pacemaker’ The SA node gives off an electrical impulse that causes the left and right atrium to contract. Controlling the cardiac cycle 1 2 3 44
  27. 27. Summary of events during the cardiac cycle
  28. 28. Lymphatic System • Most tissue fluid is returned to the blood plasma via the capillaries. • Remaining tissue fluid enters the lymph vessels – drain back into the veins close to the heart. • This fluid is now called lymph. • Lymph nodes filter lymph and play an important role in the body’s defence.
  29. 29. Lymphatic System
  30. 30. Diseases of the Heart and Circulatory System • Cardiovascular Diseases are caused by a build-up of cholesterol fibres, dead muscle cells and platelets on the inside of the coronary artery, called an atheroma which reduces the flow of blood and therefore oxygen to the tissues.
  31. 31. Diseases of the Heart and Circulatory System • If the atheroma breaks through the endothelium (cells lining the inside of the artery) it forms a rough surface that interrupts the smooth flow of blood. This may result in formation of a blood clot or thrombus. • This is known as thrombosis. The thrombus may block the blood vessel reducing or preventing blood supply to the tissues (cardiac muscle).
  32. 32. Diseases of the Heart and Circulatory System • The plaque weakens the wall of the artery. The weakened points swell to form a balloon- like structure called an aneurysm. • If the wall is particularly weak it may burst causing a haemorrhage or blood loss and possibly death.
  33. 33. Diseases of the Heart and Circulatory System • Any cardiac cells that are supplied by this blood vessel will be starved of oxygen and glucose and therefore cannot respire. • These cells will die – this is called a myocardial infarction or heart attack.
  34. 34. Diseases of the Heart and Circulatory System • A stroke occurs if an artery in the brain bursts and blood leaks into the brain tissue or when an artery supplying the brain becomes blocked. • The brain tissue becomes starved of oxygen and dies. Strokes can be fatal or very mild and may affect speech, memory and control of the body.
  35. 35. Diseases of the Heart and Circulatory System • High blood pressure increases the risk of an aneurysm and stimulates thickening of artery walls, increasing the risk of thrombosis. • Prolonged stress, diet and lack of exercise can all increase blood pressure. • High blood pressure increases the risk of heart disease because:  Higher pressure in arteries means the heart has to work harder to pump blood into them – therefore increases risk of failure.  To resist higher pressure the walls of the arteries thicken, which restricts the blood flow.
  36. 36. Re-purposed from Circulatory System of a Mammal. Retrieved 3 April, from Vessels-and-Tissue-Fluid-6070763/ Controlling the Heartbeat. Retrieved 3 April, from heartbeat-ELSS-Biology-6412761/ Heart and Heart Diseases. Retrieved 3 April, 2014, from Biology-Heart-and-amp-Heart-Diseases-6380648/ The Circulatory System. Retrieved 3 April, 2014, from System-6345574/ Transport in Animals. Retrieved 3 April, 2014, from Animals-6400934/