Transport of oxygen

• What is Myoglobin?

  A red protein that carries and stores oxygen in muscle cells it is structurally similar to haemoglobin.

  It has a higher affinity with O2 therefore O2 dissociates from oxyhaemoglobin and binds to myoglobin to form oxymyoglobin. This is then stored in the muscles for mitochondria to use in energy production.
• What is the impact of the Bohr Shift during exercise?

  Increased dissociation of O2 from Haemoglobin which results in more O2 leaving the blood and entering the muscles. (enhanced aerobic capacity & better performance)
• What are the factors that effect the Bohr Shift?

  Increase in blood temperature - when blood and temperature of the muscles increase during exercise the oxygen will dissociate from haemoglobin more readily.

  Increase in CO2 concentration at muscles - as level of CO2 rises during exercise O2 will dissociate quicker from haemoglobin

  Increases blood acidity (decreased pH levels) - more carbon dioxide = lower blood pH. A drop in pH will cause oxygen to dissociate from haemoglobin more quickly (Bohr shift).
• What is Venous Return?

  Blood in the veins that returns back to the heart via the vena cava
• What Mechanisms allow Venous Return?

  1. Pocket Valves - located in veins, these snap shut to prevent back flow of blood.

  
  

  2. Smooth muscle - there is a ring of smooth muscle within the vein that contracts to squeeze blood through and increases blood flow.

  
  

  3. Gravity - blood located above the heart will be drawn back due to this force.

  
  

  4. Respiratory pump - inspiration causes an increase in pressure in the chest area (thoracic cavity) this compresses the veins and squeezes the blood through and increases blood flow.

  
  

  5. Skeletal Muscle Pump - when the skeletal muscles contract they cause the veins to be compressed and this squeezes the blood through and increases blood flow.

  
  

  6. Suction Pump - the heart is a pump and as blood returns back in the veins it is sucked in the to heart.
• How is Oxygen carried around the body?

  97% is carried with Haemoglobin in the form of oxyhaemoglobin

  
  

  3 % dissolves in the blood plasma
• How is Carbondioxide carried around the body?

  70 % is transported in the blood as carbonic acid

  
  

  23% combines with haemoglobin to form carbominoglobin

  
  

  7% dissolves into blood plasma
• What is A-VO2diff ?

  The difference in oxygen levels in the blood between the arteriole and the venules.

  
  

  i.e the amount of O2 that is use / diffuses out at the capillaries
• What happens to A-VO2diff during exercise, and what is the impact of this?

  A-VO2diff increases, therefore more O2 is used.

  More O2 will allow greater production of ATP (energy produced in the muscle via aerobic respiration),

  therefore better performance for longer period of time.
• What are the structural and functional features of Venules and Veins?

  Transport blood back to the heart.

  
  

  Pocket valves to prevent backflow.

  
  

  Wider Lumen wich results in lower blood pressure.

  
  

  Less elasticity then an artery

  
  

  Walls have a thin Layer of muscle
• What are the structural and functional features of Capillaries?

  To provide a site for gaseous exchange.

  
  

  Walls are one cell thick and have a short diffusion

  pathway for gases to move.

  
  

  Very narrow to slow the flow of blood to maximise diffusion.

  
  

  Large surface area to support diffusion

  
• What are the structural and functional features of Arteries & Arteriols?

  They transport blood away from the heart.

  
  

  Thick walls with elastic fibres to deal with high blood pressure and speed of blood flow.

  
  

  Smaller Lumen.

  
  

  Have a ring of muscle which allows vasoconstriction and vasodilation (to change the direction of blood flow in the body, i.e blood shunting)
• What is Vasoconstriction?

  the closing of the arterioles to restrict the flow of blood in a certain direction. e.g during exercise the arterioles that carry blood to the liver and gut are closed as blood needs to be directed else where.
• What is Vasodilation?

  the opening of the arterioles to increase the flow of blood in a certain direction. e.g during exercise the arterioles that carry blood to the working skeletal muscles, heart, and skin (to control body temperature) will open.
• Why does blood flow to the brain always remain the same for either rest or exercise?

  There is always a constant oxygen supplied required for the brain to function. The blood is rich in oxygen and nutrients that are required.
• Why should you not eat before exercising?

  Blood has been shunted to skeletal muscles and away from digestive system. Exercising will either cause sickness or cause a change in blood flow back to digestive system and this will decrease O2 to muscles and therefore decrease performance.