3.4 Mass Transport in Animals Flashcards
What is the structure of haemoglobin?
A quaternary structure - 4 polypeptide chains
Bonds: peptide, hydrogen, ionic and di-sulfide bridges
Contains 4 prosthetic haem groups
Contains iron in the haem group
What is the role of haemoglobin?
To transport oxygen by binding to it in the haem group to form oxyhemoglobin
How does haemoglobin need to be efficient at transporting oxygen?
Needs to:
Readily associate with the oxygen where gas exchange takes place
And
Readily disassociate from oxygen at tissues requiring it
What is the equation to do with haemoglobin and where do they take place?
Hb + O2 ⇌ HbO8
Forwards: in the lungs (high oxygen partial pressure) from alveoli to capillaries called association ie loading of oxygen
Backwards: in the muscles - lower oxygen partial pressure (being used up for aerobic respiration) called disassociation ie unloading of oxygen
How can haemoglobin be able to associate and disassociate oxygen?
Haemoglobin has different affinities
High affinity = takes up oxygen easily but releases it less readily
Low affinity = takes up oxygen less easily but releases it more readily
Oxygen has different affinities under different conditions: Gas exchange surface?
High oxygen concentration
Low carbon dioxide concentration
High affinity of haemoglobin for oxygen
Therefore oxygen is attached
Oxygen has different affinities under different conditions: Repairing tissues?
Low oxygen concentration
High carbon dioxide concentration
Low affinity of haemoglobin for oxygen
Therefore oxygen is dettached/released
If an organism lived in a low oxygen region (eg llama) what is the ideal affinity?
High affinity
If an organism had a high metabolic rate (eg hummingbird) what is the ideal affinity?
Low affinity
Therefore unloading more oxygen as aerobic respiration takes place faster as more energy is needed
Describe the oxygen disassociation curve for haemoglobin?
S - shape
Never reaches 100% - highest saturation is 98%
What is happening at the top of the oxygen disassociation curve?
Haemoglobin has a high affinity for oxygen
It is very saturated
It loads the oxygen easily
What is happening at the bottom of the oxygen disassociation curve?
Haemoglobin has a low affinity for oxygen
It isn’t very saturated
It unloads the oxygen easily for aerobic respiration
Why would a oxygen disassociation curve by beneficial moving to the right?
Right Reduced affinity Releases oxygen for Respiration Really high metabolic rate (if applies)
Why would a oxygen disassociation curve by beneficial moving to the left?
Left Lift affinity Load O2 Locomotion to cells Low O2 environment (if applies)
If the oxygen disassociation curve moves what is this called?
The Bohr shift
If the rate of respiration is high how does this effect haemoglobin?
More CO2 being produced Lowers the pH (carbonic acid) The greater the change in haemoglobin shape (loosely knit = high affinity) The more oxygen is unloaded Therefore more available for respiration
Why is having a double circulation (goes through the heart twice) an advantage?
To pick up oxygen
Doesn’t damage the lungs as a lower pressure is used on the right side
What does pulmonary relate to?
The lungs
What does hepatic relate to?
The liver
What does renal relate to?
Kidneys