Chapter 7 Flashcards
What structure does haemoglobin have?
Quaternary
What is haemoglobin evolved to do?
Load and unload oxygen under different sets of conditions
How many polypeptide chains does haemoglobin have?
4
What shape does haemoglobin appear to be?
Spherical
What is the process by which oxygen binds to haemoglobin called?
associating or loading
What is the process by which haemoglobin releases its oxygen callled?
Dissociating or unloading
What is the overall role of haemoglobin?
To carry oxygen
In order to fufil its role, haemoglobin has to …
readily associate with oxygen at the surface of the gas exchange site
readily dissociate with oxygen at the tissues requiring it
What is affinity?
Chemical attraction
How does haemoglobin unload and load oxygen at the right conditions?
It changes its affinity for oxygen under different conditions. It achieves this by changing its shape in the presence of CO2. In the presence of CO2, the haemoglobin molecule changes shape to one that has less affinity for oxygen, and therefore it is released
When haemoglobin is exposed to partial pressures of oxygen it…
doesnt bond evenly
In a lower partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
little oxygen bonds to the haemoglobin, and the gradient of the curve is shallow. bc the shape of the molecule makes it difficult for the 1st oxygen molecule to bind to one of the 4 sites of the polypeptide subunits, as they are closely packed.
In a medium partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
The binding of O2 to haemoglobin becomes easier, as the shape of the haemoglobin molecule changes shape on binding with oxygen, making it easier for other molecules to bind to it, and the gradient curve steepens
In a high partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
The binding of the 4th molecule of O2 becomes harder, as it is more difficult to find somewhere to bind to , and the gradient curve levels out
Haemoglobin as a reduced affinity for O2 in the presence of what molecule?
carbon dioxide
The greater the concentration of carbon dioxide, the ___________ the haemoglobin molecule releases the oxygen molecule
more readily
At the gas exchange site, is affinity for oxygen higher or lower and why?
Higher, because concentrations of CO2 are lower as they are diffusing out of the organism, as well as this, there are high levels of O2, and means oxygen is readily associated with haemoglobin
At the respiring tissues, is affinity for oxygen higher or lower and why?
Lower, because concentrations of CO2 are higher as they are being produced during respiration , as well as this, there are low levels of O2, and means oxygen is readily dissociated from haemoglobin
Why does a high concentration of CO2 affect haemoglobin’s affinity for oxygen?
Becase CO2 is acidic when it is dissolved, bonds are broken within haemoglobin that causes a shape change, that enables it to have a lower affinity for oxygen and causes it to unload into respiring cells
Why does a low concentration of CO2 affect haemoglobin’s affinity for oxygen?
In low concentrations of CO2, the gas exchange surface has a slightly higher pH, and this causes the haemoglobin to change shape into one that enables it to load O2 more readily and increases its affinity for haemoglobin so oxygen isnt released in the blood.
In practice, due to atmospheric pressure, how many oxygen molecules bind to haemoglobin?
3
When haemoglobin reaches a tissue with a high respiratory rate, how many oxygen molecules are unloaded?
3
When haemoglobin reaches a tissue with a low respiratory rate, how many oxygen molecules are unloaded?
1
Why do large organisms have transport systems?
Diffusion isnt fast enough to transport all the required substances in and out of large organisms, so specialist exchange surfaces are used to absorb nutrients and respiratory gases and release waste productsq
List 5 features of transport systems
- Have a suitable medium to carry materials
- The transport system transports substances more quickly than diffusion
- Is formed of a closed system with a branching network of wessels
- Has a mechanism for moving substances within the vessel
- Has a mechanism to move substances in 1 direction
What type of circulatory system do mammals have?
Closed double circulatory system where blood is confined to the vessels and passes through the heart twice for each circuit of the body
Why do mammals need a double circulatory system?
Because when blood is passed through the lungs, the pressure is reduced, and if it were to pass to the rest of the body the low pressure would make circulation very slow, by passing the blood through the heart again, pressure is increased and blood is passed through the body very quickly
Do mammals have a high or low metabolic rate?
High
Do mammals have high or low respiratory rates?
High
What is the final method of moving substances from the capillary wall to the cells?
Via diffusion
What are the 2 types of heart chambers?
Atrium and ventricle
Which side of the heart does the deoxygenated blood go in?
right
Which side of the heart does the oxygenated blood go in?
left
List the 4 major vessels
Aorta
Vena Cava
Pulmonary vein
Pulmonary artery
Where is the aorta connected to?
The left ventricle
Where is the Vena cava connected to?
The right atrium