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Pack 8 - Mass Transport, Left Ventricle, Tough Outer layer, Muscle Layer,…

- - - - No nucleus - greater volume for haemoglobin
      - Bi-concave shape - increased SA: Volume
      - Flexible plasma membrane - squeeze through narrow capillaries
      - Selectively permeable
      - Contains Haemoglobin
        
        Haemoglobin
        
        4 protein chains (quaternary structures)
        
        Conjugated group - non-protein part
        
        Prosthetic group - Fe2+
        
        When haemoglobin picks up O2 -Loading. When it drops it off -Unloading
  - - - Co-operative nature of oxygen binding
      - Opposite occurs when unloading - first molecule released faster than subsequent
    - - At lungs
        
        Gas exchange surfaces, CO2 constantly being removed
        
        Raises pH slightly due to low concentration of CO2
        
        Higher pH changes shape of haemoglobin into one that enables it to load oxygen
        
        The shape also increases the affinity of haemoglobin for oxygen, so it is not released while being transported in the blood to the tissue
      - At tissues
        
        tissues, CO2 is constantly being produced
        
        Lowers pH slightly as CO2 is acidic in solution
        
        Lower pH changes shape of haemoglobin into one that enables it to unload oxygen
        
        shape also decreases the affinity of haemoglobin for oxygen so oxygen is released into the respiring cells
    - - Higher affinity ODC left
        
        Organisms living in high altitudes
        
        Organisms living underground/habitats with low oxygen(pond)
        
        Myoglobin -O2 store in muscles
        
        Foetal heamoglobin
      - Lower Affinity ODC right
        
        Small animals
        
        Active animals
  - - - Blood cells suspended in plasma
    - - 95% water, contains dissolved proteins, ions, sugars and O2
    - - Fluid surrounding cells of the body - similar to plasma but no proteins and blood cells - supplies nutrients and removes waste
    - - Hydrostatic pressure v high forcing fluid out (ultrafiltration). Water potential low so some water moving in to the capillaries via osmosis but not as much as moving out
    - - Volume increased a lot so hydrostatic pressure decreased a lot. Water potential still low(due to proteins in plasma) so water moves back into capillaries via osmosis
      - Excess fluid drains into lymph system and returns to bloodstream at neck
  - - - Benefits - Oxygenated + Deoxygenated blood don't mix. Gas exchange maximised because lungs receive blood with low O2 conc. Separate circuits can operate at different pressures
    - - Diastole
        
        Blood enters atria and ventricles from veins. SL valves closed. AV valves open. relaxation of ventricles allows blood to enter from atria
      - Atrial Systole
        
        Atria contract -pushing remaining blood into ventricles. SL valves closed. AV valves open
      - Ventricular Systole
        
        Atria relax, ventricles contract - pushing blood away from heart through arteries. SL valves open. AV valves closed
    - - Atrioventricular Valves
        
        Between atrium + ventricle
        
        Prevent backflow to atrium when ventricles contract, close when pressure in ventricles>atria
      - Semi-Lunar Valves
        
        In aorta + pulmonary artery
        
        Prevent backflow to ventricles, close when pressure in arteries > vetricles
      - Pocket Valves
        
        In veins
        
        Prevent backflow when veins squeezed and pressure increases
    - - Veins
      - Capillaries
      - Arteries
      - Arterioles
- - - - Substances needed could not be supplied through its external surfaces. Oxygen passing through would be rapidly used up. Waste substances could not be removed
  - - - A form of mass transport
        
        A closed system of vessels that contain the medium and form a branching system to distribute to all parts of the organism
        
        A mechanism to move the medium - requires pressure difference in system
        
        All the substances move in the same direction at the same speed
        
        Other requirements
        
        Mechanism to maintain mass flow in one direction, eg valves
        
        Means of controlling the flow to suit the changing needs of the organism
        
        Mechanism for mass flow of water or gases
- - - - Change in water potential cause water to move in from neighbouring cell via osmosis- repeats through the cells in the leaf
    - - Pathway though cell walls Not osmosis in plants as no partially permeable membrane
    - - Pathway through cells cytoplasm and through gap in cell wall called plasmodesmata - Osmosis
    - - No cytoplasm + nucleus - don't reduce flow
      - End walls destroyed to produce tubes
      - Cell wall coasted in lignin to stop it being permeable and give strength
      - Pits left in cell wall to allow lateral diffusion to bypass blockages
    - - Hydrogen bonds allow adhesion between water molecules and cellulose xylem wall
      - Hydrogen bonds allow cohesion between water molecules in xylem
  - - - Some sucrose passes through into companion cell via symplast route, some via apoplast route
      - Proton pump moves H+ into companion cell via active transport. The sucrose passes into the sieve tube element via co-transport with hydrogen ions
    - - Moves into sink cell via companion cell by active transport. Increased water potential in the sieve tube due to removal of sucrose
      - Decrease in water potential in the sink cell cause water to move in via osmosis increasing hydrostatic pressure.
    - - Now has lower water potential (due to sucrose) than xylem. Water moves in via osmosis increase hydrostatic pressure
      - Mass transport moves the water down the gradient
    - - Cells that lie next to phloem, contain rough ER and nucleus, have a large number of mitochondria and many plasmodesmata in the lateral walls.
- - - - Right Atrium
        
        Right AV Valve (Tricuspid)
        
        Right Ventricle
        
        Pulmonary Artery
        
        Lungs
        
        Pulmonary vein
        
        1 more item...
        
        Semi-lunar valves
- - - - No
- - - - No
- - - - No
- - - - Thin, short DD
- - - - Very narrow - slow blood cells
- - - - No