3.3.4.1 Mass Transport in Animals Flashcards
What is haemoglobin?
It is a group of chemically similar protein molecules
What is the structure of haemoglobin?
Quaternary protein structure
Each polypeptide is associated with a haem group- contains a ferrous Fe2+ ion
Each ferrous ion can bond with one O2 molecule
What is the name of the process where oxygen is released from haemoglobin molecules?
Unloading or dissociating
What is the name of the process where oxygen binds to haemoglobin molecules?
Loading or associating
What must haemoglobin do to be efficient at transporting oxygen?
Readily associate with oxygen at the gas exchange surface
Readily dissociate from oxygen at the tissues
These two have to be balanced
How is haemoglobin efficient at transporting oxygen?
Its shape changes in the presence of certain substances, such as CO2
In the acidity caused by CO2, the new shape of the haemoglobin molecule binds more loosely to oxygen
Why are there different haemoglobins?
Different affinities of oxygen allow for different uses across the different needs of species which survive in different environmental conditions
What is the oxygen dissociation curve?
The graph of the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen
What is the explanation of the oxygen dissociation curve?
- shape makes first oxygen molecule hard to bind, at low oxygen concentrations the gradient is shallow
- first binding oxygen changes the molecule shape, this makes it easier for three extra oxygen molecules
- positive cooperativity where it takes a smaller increase in partial pressure for the 2nd oxygen to bind, gradient of the curve steepens
- after 3rd binding, binding site is harder to find because of probability, gradient reduces, graph flattens off
How can different oxygen association curves be interpreted?
The further left it is, the greater the affinity for oxygen so it loads readily but unloading isn’t as easy
And vice versa
What is partial pressure?
The pressure that the amount of gas contributes to the total pressure of the gas mixture
Measured in kiloPascals
How is haemoglobin affected at the gas exchange surface?
Concentration of CO2 is low because it diffuses across
Oxygen affinity is increased
High concentration of oxygen in lungs
Oxygen is readily loaded by haemoglobin
Reduced CO2 concentration shifts the oxygen dissociation curve to the left
How is haemoglobin affected at rapidly respiring tissues?
CO2 concentration is high
Affinity for oxygen is reduced
Oxygen is readily unloaded from the haemoglobin into muscle cells
Oxygen dissociation curve is shifted to the right
Why does an increased CO2 concentration cause the release of oxygen?
Dissolved CO2 is acidic and low pH cause haemoglobin to change shape
What is the process for loading, transport and unloading of oxygen by haemoglobin?
At gas-exchange surface, CO2 is constantly being removed
pH is slightly raised due to low concentration of CO2
Higher pH changes haemoglobin shape, it loads oxygen readily
Shape also increases affinity so it isn’t released while being transported to tissues
In tissues CO2 is being produced by respiring cells
CO2 is acidic so the pH of the blood in the tissues is lowered
Lower pH changes the shape of haemoglobin into one with a lower affinity for oxygen
Haemoglobin releases its oxygen into respiring tissues
What is the relationship between the activeness of a tissue and the loading, transport and unloading of oxygen by haemoglobin?
The more active a cell is, the more oxygen is unloaded
What is the mammalian system of transport?
A mass transport system due to the large distances
Specialist exchange surfaces to absorb nutrients and respiratory gases and remove excretory muscles
What are the common features of the mammalian transport system?
Suitable medium in which to carry materials
A form of mass transport in which the transport medium is moved around in bulk over large distances
Closed system of tubular vessels that distributes the transport medium
A mechanism for moving the transport medium within vessels
How do mammals move the transport medium within vessels?
Muscular contraction, either of body muscles or a specialised pumping organ
What is the type of circulation system that a mammal has?
Closed, double circulatory system
Blood is confined to vessels and passes twice through the heart for each complete circuit of the body
Why does a mammal need a double circulation system?
When blood is passed through the lungs its pressure is reduced and circulation would be slow so blood is returned to the heart to boost its pressure and make it move faster
Why do mammals need a fast circulation system?
They have a high metabolism which is why substances need to be transported quickly
Why is the final exchange from blood vessels rapid?
A large surface area
Short distances
A steep diffusion gradient
Which side of the heart deals with which type of blood?
Left side deals with oxygenated blood from the lungs
Right side deals with deoxygenated blood from the body
What is the atrium?
Thin walled, elastic, stretches, collects blood
What is a ventricle?
Contracts strongly to pump blood, has a much thicker muscular wall
What does the right ventricle do?
It pumps blood to the lungs
Has a thinner muscular wall than the left
What is the timing of the atria and ventricles?
Atria contract together
Ventricles contract together
What lies between the atrium and the ventricle?
Valves that prevent backflow to blood into the atria when ventricles contract
Left is the left atrioventricular (bicuspid) valve
Right is the right atrioventricular (tricuspid) valve
What is the name of the vessels which connect the heart to the lungs?
Pulmonary vessels
What does the aorta do?
It carries oxygenated blood to all parts of the body except the lungs
It is connected to the left ventricle
What does the pulmonary artery do?
It carries deoxygenated blood to the lungs where oxygen is added and carbon dioxide is removed
It is connected to the right ventricle
What does the pulmonary vein do?
It brings oxygenated blood back from the lungs
It is connected to the left atrium
What are the two phases of the cardiac cycle?
Contraction (systole) and relaxation (diastole)
Are the ventricles and atria in sync during relaxation and contraction?
Contraction occurs separately in the ventricles and atria
Relaxation occurs almost simultaneously in all chambers
What are the steps of relaxation of the heart?
Diastole Atria and ventricles are relaxed Atria fill with blood Semi lunar valves closed Left and right atrioventricular valves closed Blood enters ventricles from atria
What are the steps of the atrial systole?
Atria contract to push remaining blood into the ventricles
Semi lunar valves are closed
Left and right atrioventricular valves are open
Ventricles remain relaxed
What are the steps of the ventricular systoles?
Blood pumped into arteries and aorta Semi lunar valves open Atrioventricular valves closed Ventricles contract and walls thicken Atria relax
What is the function of valves?
They prevent the backflow of blood
What is the function of atrioventricular valves?
They prevent backflow of blood when contraction of the ventricles means that ventricular pressure exceeds atrial pressure
Closure means that blood moves to the aorta and not back into the atria