transport in animals

• substances dissolved in the plasma can pass through fenestrations in capillary walls with the exemption of large plasma proteins
• plasma proteins have a osmotic effect with a high solute potential and low water potential and this results in water moving into the blood
• oncotic pressure = tendency of water to move into the blood
• in the arterial end, hydrostatic pressure is greater than oncotic pressure so fluid is squeezed out of the capillary and fills the space between cells
• at the arterial end of the capillary the hydrostatic pressure forces blood out of the capillaries
• as blood flows through arterioles into capillaries its under pressure from the hearts contraction this is hydrostatic pressure
• in the venous end hydrostatic pressure drops so oncotic pressure is now greater causing the water from surrounding fluid to move back into the capillaries
• oncotic pressure of blood is -3.3kPa
• the fluid left behind drains into the lymphatic system where it becomes lymph fluid and contains less oxygen and nutrients
• lymph fluid contains fatty acids from villi in small intestine
• eventually lymph fluid is returned to the blood via lymph vessels
• lymph nodes have lymphocytes which produce antinodes that are passed into the blood
• chloride shift is the movement of chloride ions into the red blood cells in exchange for hydrogen carbonate in order to balance out the charge
• 5% of carbon dioxide goes into blood plasma
• 10 % of carbon dioxide binds directly with haemoglobin to form carboaminohaemoglonin
• 85% of carbon dioxide goes into the red blood cell
• within the red blood cell

  1. carbon dioxide combines with water to form carbonic acid with enzyme carbonic anhydrase
  2. dissociation so hydrogen carbonate ions diffuses out of the cell and the hydrogen ions combine with haemoglobin to form haemoglobinic acid
  3. When hydrogen carbonate ions diffuses out in order to balance out the charge chloride ions diffuse into the red blood cell
• carboaminohaemoglobin and haemoglonic acid when formed the tertiary structure of haemoglobin changes so can let go of the oxygen and have a lower affinity
• hydrogen ions combine with haemoglobin in order to prevent the hydrogen ions from changing pH
• elastic fibres = stretch and recoil providing walls of vessels with elasticity
• smooth muscle = contract and relaxes which changes the lumen size
• collagen = structural support to maintain the shape and volume of the vessels
• arteries carry blood away from the heart and oxygenated blood with the exception of pulmonary artery and umbilical artery.
• arteries carry blood at high pressure so have thick elastic walls to withstand the force of the blood coming out of the heart
• In between contractions of the heart, the elastic fibres in arteries recoil and return to original shape which helps even out the surges of blood to give a continuous flow of blood
• Arterioles link arteries with capillaries and contain more smooth muscle and less elastin which creates a little pulse surge. They can constrict and dilate to control the blood flow to capillaries and organs
• capillaries link arterioles and venules within tissues
• capillaries have a small lumen so red blood cells can travel through single file for gaseous exchange
• capillaries contain gaps between endothelium cells for subtle exchange
• in most organs capillaries enter with oxygenated blood and leave with a little less oxygenated blood expect the lungs and placenta
• capillaries adaptions

  • have a large surface area
  • cross-sectional area is larger than arterioles so that the rate of blood flow falls for more time to exchange substances
  • thin walls for diffusion of substances t
• veins carry blood away form cells and towards the heart and mostly deoxygenated blood expect pulmonary vein
• veins have no pulse but can hold up to 60% of bloods volume
• veins contain lots of collagen and little elastin, they also have a large lumen with endothelium lining
• venules connect capillaries and veins and they have very thin walls with only collagen
• veins adaptations

  • move against gravity
  • many big veins run between muscles so when muscles contract they squeeze the veins and blood flow towards heart
  • contain valves to prevent backlog of blood
• tachycardia is when the heart beats over 100bpm
• bradycardia is when the heart beats slowly and under 60bpm
• ectopic = extra beats occur too early and are followed by a large pause in beats
• atrial fibrillation = type of arrhythmia which is abnormal atria and ventricle lose regular rhythm and don't pump effectively. The electrical impulse in the heart is rapid