Mass Transport (haemoglobin) Flashcards
Define mass transport
Bulk movement of liquid or gas in one direction
What determines the need for a mass tansport system and a pump?
Sa:vol
Rate of metabolism
Small sa:vol = not enough substances can be exchanged quick enough to supply volume do to long diffusion pathway
High rate of metabolism= many substances bed to be exchanged in a short amount of time= diffusion doesn’t take place quick enough
Need pump and mass transport system
Name features of mass transport system
Closed system Mechanisms to control rate of flow Mechanisms to ensure unidirectional flow Mechanisms for mass flow Suitable medium (gas or liquid)
Explain the importance of a suitable medium to a mass transport system
Must be able to Dissolve substances (e.g water)
To transport them easily
Explain the importance of having a mechanism for mass flow to a mass transport system
More rapid than diffusion
Maintain conc gradient
Explain the importance of a closed to a mass transport system
Allows all cells to be reached
Allows pressure variation for flow of substances
Explain the importance of unidirectional flow to a mass transport system
Prevent back flow
Maintain conc gradient
Explain the importance of controlling the rate of flow in a mass transport system
Adapt to the changing needs of tissues
Why are humans said to have a double circulatory system?
Blood flows in two loops to and from the heart
Pulmonary circulation (to lungs and back)
Systemic circulation (to body and back)
Two sides of the heart
Why is a double circulatory system required in humans?
Allows high pressure to be maintained
Pa reduced in lungs as goes through pulmonary capillaries
Low pa= slow flow= wouldn’t reach tissue fast enough, not returned to heart fast enough
Name arteries and veins supplying kidneys
Renal arteries/veins
How are redblood cells adapted for oxygen transport?
Biconcave disc= flexible (scrap along cappilary walls to provide short diffusion pathway) + short diffusion pathway (thin middle) + larger sa:vol
No organelles= more space for haemoglobin + flexible
Small= compressed against capillary walls (sdp)
Why is it an advantage for rbc to be flexible?
Allows them to scrap along and be compressed against capillary walls= sdp
Describe 1° structure of haemoglobin
Specific sequence of Amino acids
Polypeptide chains=
2 X alpha
2 X beta
Describe 2° structure of haemoglobin
Polypeptide chains coil into alpha helices
Describe 3° structure of haemoglobin
Polypeptide chains fold again into specific 3D shape
Describe 4° structure of haemoglobin
4 polypeptide chains associate to form a roughly spherical shape
Each polypeptide associates with one haem group (containing ferrous iron ion Fe2+)
How many oxygen atoms can one heam group bond to?
2x oxygen ATOMS
1x oxygen MOLECULE
How many oxygen molecules and atoms can one haemoglobin molecule carry ?
8 atoms
4 molecules
What is haemoglobin role and how is it adapted to this?
Load oxygen at lungs unload oxygen at respiring tissue
Have high affinity at high ppa but low affinity at high ppa
Define affinity
Chemical attraction
Define loading of oxygen
Association of an O2 molecule to a haem group
Define unloading of O2
Dissociation of O2 molecule
What affect haemoglobin shape?
CO2 conc
DNA (1° structure)
Where is the partial pressure of O2 low?
At respiring tissue as its being used for Respiration
What is an oxygen dissociation curve
Graph showing average saturation of haemoglobin (y) against ppa of O2 (X)
What does the oxygen dissociation curve show? How?
Bind of 1st oxygen molecule if hardest (shallow gradient)
Binding of second and third is increasingly easier (increasing gradient= small increase in partial pressure causes lots more O2 to bind)
Binding of 4th O2 is harder (shallowing gradient)
Define positive cooperativity
Binding of first O2 makes binding or 2nd and 3rd easier
Describe and explain positive cooperativity
Bind of 1st oxygen molecule if hardest because globins are compact
Binding of second and third is increasingly easier because binding of 1st O2 changes haemoglobin shape making binding easier
Binding of 4th O2 is harder due to probability (only 1 haem group left to bind)
Define partial pressure
Pressure exerted by one gas if it singly occupied to same volume
Why Is ppa more useful than concentration
Concentration of O2 is constant
Ppa varies due to how many particles of gases are in the air (same composition but differ e renumber of particles= different pressure exerted)
Why is oxygen only unloaded at respiring tissue?
Ppa of O2 in blood is roughly constant
Name the effect of CO2 on haemoglobin
Bohr effect
Describe and explain the bohr effect
Increase rate of Respiration= increase CO2 conc= decrease PH = change in shape to haemoglobin = decreased affinity for O2= O2 is readily unloaded/dissociated =O2 available for Respiration
Why does increase in CO2 conc mean a decrease in PH?
CO2 dissolves in blood plasma to form carbonic acid
Compared the change in oxygen affinity for large and small changes in CO2 conc
Small change = small change in affinity
Large change =large change in affinity
In which direction does the oxygen dissociation curve move with an increase in CO2 conc? Why?
Right
At all ppa’s % sat is always lower (more readily unloads)
In which direction does the oxygen dissociation curve move with an decrease in CO2 conc? Why?
Left
Always a higher % sat (more readily loads)
How do you calculate partial pressure?
Concentration X atmospheric pressure
How does a large sa:vol affect the oxygen dissociation curve? Why?
Move to right
Lose heat fast = large rate of Respiration = large demand for O2 (needs to readily unload)
How does the oxygen dissociation curve move for a cold animal? Why?
To left
Cold= slower rate of Respiration = less demand for O2 = less demand for O2 (doesn’t need to unload as much)
