3.4 Mass transport Flashcards
Describe the structure of hemoglobin
Globular
Water solouble
Contains 4 polypeptide chains
Each contains a haem group
Describe the role of hemoglobin?
Present in red blood cells
O2 binds to each heam group and is carried around the body and given to respiring cells
Name three factors affecting the oxygen-hemoglobin binding?
- Partial pressure/concentration of oxygen
- Partial pressure/concentration of CO2
- Saturation of haemglobin and oxygen
How does the partial pressure of oxygen affect the oxygen-hemoglobin binding?
When the partial pressure increase the affinity of oxygen and heamoglobin increases and so it is binded tightly.
However, when the partial pressure is low the oxygen is released from the hemoglobin
How does the partial pressure of CO2 affect the oxygen-hemoglobin binding?
As the partial pressure of the co2 increases, the affinity of the hemoglobin and oxygen decreases. This is because this dissolves and forms carbonic acid which decreases the ph and is acidic. This means that the hemoglobin changes shape and the o2 can no longer bind to it . The affinity decreases and therefore it’s released.
This is called Bohr affect
How does the saturation of hemoglobin affect the oxygen-hemoglobin binding?
It is hard for the first O2 molecules to bind.
However, it then makes it easier for the 2nd and 3rd molecule to bind as it changes shape.
it is then slightly harder for the last one because its harder to find a binding site
-Positive cooperativity
Explain why o2 binds to hemoglobin in the lungs?
- Partial pressure of 02 is high in the lungs
- Partial pressure of co2 is low and so higher affinity
- Positive cooperativity
Explain why o2 is released in respiring tissue
- Lower partial pressure of O2
- Higher partial pressure of CO2 and so lower affinty
What do oxyhemoglobin curve show
Perrcentage of saturation plotted against partial pressure of o2 (KPa). The curve shifted more to the left shows higher affinity
Name the common features of a mammalian circulatory system
-Suitable medium for transport
water-based to allow for substances to dissolve
- Means of moving the medium and maintaing a pressure such as the heart
- Means of controlling flow so it remains undirectional such as the valve
Relate the structure of the heart chambers to their function
Atria: thin-walled and elastic
Has to stretch when its filling up with blood
Ventricle: Thick muscular wallas to help pump blood under high pressure.
Left is thicker than the right because it has
to pump blood to the whole body.
Relate the structure of the vessels to their function
Arteries: They have thick walls to handle high pressure without tearing
They have muscles and are elastic to control blood flow
Elastic tissue stretches and recoils to cope with high pressure.
Veins have thin walls because of the low pressure and so they also have valves which stop it from flowing backwards
Why are there 2 pumps instead of just 1?
To maintain blood pressure throughout the whole body.
When the blood is flowing through the narrow capillaries of the lung the pressure drops drastically and needs to go back to the heart to be pumped otherwise it will not be able to pump to the rest of the body
Describe what happens in cardiac diastole
The atria and ventricles relax
Blood enters the atria
Pressure and volume of atria increases
This causes the atrioventricular valve to open and blood flows to the ventricles down a pressure gradient
Pressure in the heart lower than arteries so semilunar valves remain closed
Describe what happens in atrial systole
The atria contracts causing any remaining blood in the artria to flow into the ventricle.
