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AS Level Biology - 8) Transport in Mammals


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You're probably quite familiar with how the heart work as a pump to transport blood around your body by now. In AS level, you will take this understanding to the next level - understanding the intricate system and the processes that goes on every time you draw a breathe.

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AS Level Biology - 8) Transport in Mammals

  1. 1. 8. Transport in Mammal And the Circulatory System
  2. 2. Why do we need a mammalian transport System  Animals – far more active than plants  Need energy for – contraction of muscles, brain power, mobility (have to find their own food), nervous system  Evolved transport system  Diffusion – too slow, the surface area is not enough
  3. 3. Pulmonary Circulation  Deoxygenated blood moving out from the right ventricles through the pulmonary arteries to the lung.  The now oxygenated blood then travels back into the left atrium from the pulmonary vein.
  4. 4. Systemic Circulation  Oxygenated blood moving out of the left ventricle through the aorta to the rest of the body.  Deoxygenated blood travelling back through the vena cava into the right atrium
  5. 5. The Blood vessels  Artery  Capillaries  Vein
  6. 6. Arteries  Vessels that transport blood at high pressure to the tissue away from the heart  Inner endothelium: Tunica intima – layer of flat squamous epithelium cells – REDUCE FRICTION  Middle layer: Tunica media – smooth muscle, collagen, elastic fiber  Outer layer: Tunica externa – Elastic fiber/ collagen fibers
  7. 7. Arteries  Strong and elastic  To withstand high pressure of blood leaving the heart (120mmhg)  Elastic fibers: Wall can stretch  Allows the heart to moderate the pressure of the blood by recoiling or stretching
  8. 8. Arterioles  Arteries branch into smaller vessels – Arterioles  Arterioles’ wall have more smooth muscle  The muscle can contract – controlling the volume of blood moving in and out of a certain body part  Vasoconstriction and vasodilation occurs with arterioles  Blood pressure drops here from 120 to 85 as arteries branch out
  9. 9. Capillaries  Arterioles further branch out into capillaries where cell will receive oxygen and give out waste  One-cell thick wall (endothelium) – 7 micrometer – just enough for Red blood Cell  Blood brought to 1 micrometer from the cell  Blood pressure drops enough for slower flow with exchange of thing  Allow diffusion to occur
  10. 10. Venules  Capillaries gradually join up to form Venules  Venules join to form veins – function: return blood to the heart
  11. 11. Veins  Blood pressure is low – no need for elastic muscles or thick wall  Larger lumen  Blood flow because the contraction of muscle around the veins  Backflow prevented by semilunar valves
  13. 13. Blood Plasma  Pale yellow liquid composing of 55% of the blood  Content: 90% water – 10% : Ions, Glucose, Urea, Plasma proteins (amino acids, hormones, enzymes, antibodies etc.)
  14. 14. Blood plasma - Importance  Contains hormones and other useful substances  Maintains pH and osmotic balance
  15. 15. Tissue Fluid  When passing through capillaries – plasma leaks into the spaces between cells forming tissue fluid  Proteins cannot pass through  White blood cells can squeeze through
  16. 16. Tissue Fluid  The process is as such:  The high blood pressure at arterial end of capillary bed – causes blood plasma to flow out of capillaries  High protein concentration in plasma = lower water potential, osmotic pressure causes plasma to flow back into capillaries at venule ends of the capillary bed  Hence tissue fluid maintains the osmotic balance of the cell  If blood pressure too high – at arterial ends too much of the plasma flow into tissue fluid and accumulates – swelling in the form of oedema
  17. 17. Lymph  90% of fluid that leaks out of capillary – seeps back  Another 10% is returned by the lymphatic system  Lymphatic systems: made up of lymph vessels  The lymphatic will allow tissue fluid to leak in  Lymph vessels have valves large enough for proteins  Lymph nodes: contain antibodies 
  18. 18. The Lymphatic system  The lymphatic system’s main job is to return blood plasma to the blood and also to maintain the osmotic balance by allowing protein to leak in from the tissue fluid  The system is also where a lot of of the white blood cells reside
  19. 19. Content of Blood  5 dm3 blood = 5 kg  5 x 1013 Red Blood Cells/ Erythrocytes  6 x 1012 Platelets  2.5 x 1011 White Blood Cells/ Leukocytes
  20. 20. Red Blood Cells  Small size = 7 micrometers  Biconcave shape  Small amount of organelles  High flexibility in membrane
  21. 21. Hemoglobin The Dissociation curve, Transport of Carbon dioxide and the Bohr Shift
  22. 22. Haemoglobin  Proteins found inside the red blood cells  They combine with oxygen to form Oxyhaemoglobin  They are tools Red blood cell uses for transporting oxygen  Each haemoglobin has 4 haem groups with each one containing an iron prosthetic group  This iron allows the molecule to combine with oxygen and hence give a red color to blood
  23. 23. The Dissociation Curve  This is a curve used to show how haemoglobin combine with oxygen at different partial pressure  It is important to show how haemoglobin pick up oxygen but also how it releases those oxygen molecules
  24. 24. The Dissociation Curve  At low partial pressure of oxygen – percentage saturation is very low – haemoglobin combines with very little, in this case 1 oxygen molecule  As partial pressure increases, it gets easier  Plus haemoglobin changes shape after first combination to make it easier for the other 3 
  25. 25. The S-Curve  We must also take in account the changes of partial pressure of Carbon Dioxide  Where there are high CO2 concentration (high partial pressure) eg. Muscle cells – usually respiring cells that actually do need oxygen  Oxygen will be released more readily  How so?
  26. 26. The Bohr Shift  When Carbon Dioxide enters the Red Blood cell, carbonic anhydrase allows it to combine with water to form Carbonic acid  The Carbonic acid dissociates into Hydrogen bicarbonate and hydrogen ions  The hydrogen ion is actually taken up by the haemoglobin  And hence the oxygen has to be released  THIS IS PERFECT, BECAUSE NOW OXYGEN IS RELEASED WHERE IT IS NEEDED MOST
  27. 27. Transport of Carbon dioxide  Because of the Bohr shift – 85% of the CO2 is now transported in the form of hydrogen bicarbonate ions  Another 10% of CO2 directly combines with haemoglobin to form Carbaminohaemoglobin  The other 5% is transported in solution
  28. 28. Problems with Oxygen Transport High Altitude, Carbon Mooxide
  29. 29. Effects of Carbon Monoxide  Haemoglobin combines very readily with Carbon monoxide – even more so than oxygen (250 times more)  To form Carboxyhaemoglobin – a very stable molecule  Now the body cannot transport oxygen  Carbon monoxide quickly diffuse through alveoli  Even 0.1% in the air may cause death by asphyxiation  They are found in cigarette smokes – hence most smokers actually have 5% of their blood permanently combined with carbon monoxide
  30. 30. Effects of High Altitude  Partial pressure of oxygen in normal air is higher than in air at high altitude  Haemoglobin becomes less saturated  Less oxygen carried around the body  Causing breathlessness and illness
  31. 31. Altitude Sickness  When the body doesn’t have enough time to adjust to the change in altitude  Increase in rate/ depth of breath  Dizziness and weakness  Arterials dilate for more oxygen transport – blood flow into the capillary bed more – oedema  Oedema in brains can lead to disorientation  The way to cure is simple – come down
  32. 32. Adaptations  If the body is allowed to acclimatized – number of Red Blood Cells increases – usually takes 2 -3 weeks  Permanent adaptations for those living at high altitudes  Broader chest – for more lung capacity  Larger right side of heart – to pump blood to the lung  More haemoglobin
  33. 33. The Heart Heart beats and how they work
  34. 34. The Heart Structure  Mass: 300 g  Size: fist  A bag of muscle filled with blood  Muscles – cardiac muscles – interconnecting cells with membranes tightly joined for electrical excitation to pass through
  35. 35. Aorta  The largest artery  Arch shape  Branches leading to the head  Main flow double back down toward the body  High pressure blood flow here  Connected to the left ventricle
  36. 36. Venae Cavae  2 large veins running vertically on the right side of the heart, Connected to the right atrium  1 vessel (superior vena cava) brings blood from rest of the body  Another brings blood from the head
  37. 37. Pulmonary Arteries/ Veins  P Artery: takes blood out of the heart to the lung – connected to the right ventricle  P Veins: Takes blood from the lung into the hear – connected to the left atrium  The revers of the rest of the body – if veins at the rest of the body carry deoxygenated blood, pulmonary veins carries oxygenated blood. Same goes for pulmonary arteries  Pulmonary artery branches off immediately to the right and left lung  Pulmonary vein returns first into then combine into one
  38. 38. Coronary arteries  Branch off from aorta  Deliver oxygen to the heart itself
  39. 39. The Cardiac Cycle  The sequence of events which make up one heartbeat  3 stages  Atrial systole  Ventricular systole  Ventricular diastole
  40. 40. Atrial Systole  Heart is filled with blood – muscle ready to contract  Muscular wall of atrial are thin – contraction do not produce much pressure  Pressure still forces Atrioventricular valves (tricuspid/ bicuspid) open  Blood flows from the atria into the ventricles  Valves in the veins prevent backflow
  41. 41. Ventricular Systole  0.1 seconds after the atria contract  Ventricles contract  Atrioventricular valves pulled shut due to the pressure in the ventricles exceeding the atria  Semi lunar valves forced open  Blood rushes into the arteries  This lasts for 0.3 seconds
  42. 42. Ventricular Diastole  The whole heart muscle relaxes  Semilunar valve shuts  Blood from veins flow into the atria – at low pressure – but thin wall of atria gives not much resistance  Blood just begins flowing into the ventricles when the atria contracts again
  43. 43. Control of heart beat  The muscles in the heart are myogenic  They naturally contract/ relaxes  The heart still has its own natural pacemaker  Sinoatrial node (SAN) - in the right atrium wall – it can still respond to the brain  SAN works a little faster than the heart  It sends excitation waves across the atrial walls – causing atrial systole
  44. 44. Control of heart beat  Muscles of the ventricle contracts 0.1 second after – this is because of the AVN  The AVN (Atrioventricular node) receives excitation wave which it withholds until the atria contracts, then it sends down to the ventricles so that they can follow in contraction  Between atria and ventricle – a band of fiber that does not conduct electrical impulse is there  The AVN send the impulse down through the purkyne tissues in the septum which travels to the rest of the ventricles