Module 3.1.2 - Transport in animals Flashcards
What are the specialised features of an erythrocyte?
Flattened bi-concave shape (large SA to volume ratio).
Large amount of haemoglobin for transporting oxygen.
No nuleus or organelles so more space for haemoglobin for oxygen.
Diameter 6-8micrometers, larger than capillary diameter. Slows blood flow to enable diffusion of oxygen.
What is the size of an erythrocyte and how does this help it’s function?
Small diameter of 7 micrometers, normal cell is 40 micrometers diameter.
Therefore haemoglobin is very close to the plasma membrane - as a result oxygen is loaded and unloaded into and out of a cell.
Capillaries are 8 micrometers wide, only one erythrocyte can go through at a time.
What is haemoglobin?
A protein making up 95% of the dry mass of a RBC. It is the means of oxygen transport around a body.
What is haemoglobin’s structure?
Haemoglobin is made from four haemoglobin groups each bound to a haem group.
Each haem group can combine with one oxygen molecule, so one haemoglobin molecule can combine with four oxygen molecules. This forms oxyhaemoglobin.
What ion does haemoglobin contain at the centre?
The haem group contains a single iron ion in the form Fe 2+.
True or false. Haemoglobin has a high affinity for oxygen?
True.
How is the saturation of haemoglobin measured?
As a percentage.
What is positive cooperativity?
As soon as one oxygen binds to a haem group, it changes the shape of the molecule and makes it easier for more oxygen to bind.
Because the oxygen is binded to the haemoglobin the free oxygen concentration gradient in the erythrocytes remains low, so a steep concentration gradient is maintained until all of the haemoglobin is saturated with oxygen.
When does oxygen bind to and leave haemoglobin?
Oxygen binds to haemoglobin when oxygen is at a high concentration and dissociates when oxygen is at a low concentration.
How is oxygen concentration measured?
The concentration of gas in a mixture of gases can be measured as the partial pressure. This is the amount of pressure the gas exerts relative to the total pressure exerted by all the gases in the mixture.
Measured with kilopascals (kPa) and is written as P(O2), P(O2) etc
What is the oxygen dissociation curve?
A graph that shows the saturation of haemoglobin at various partial pressures of oxygen.
LOOK AT POWERPOINT OR BOOKLET FOR OXYGEN DISSOCIATION CURVE GRAPHS.
What is the trend with oxygen dissociation?
Generally, the greater the concentration of oxygen, the greater the affinity.
In the lungs the partial pressure is high so haemogloin has a 95-97% saturation of haemoglobin.
At respiring tissues, partial pressure is low, so haemoglobin loses oxygen to 20-25% concentration.
How is fetal haemoglobin different to adult haemoglobin?
Fetal haemoglobin has a higher affinity for oxygen.
This is because fetal haemoglobin has to associate with oxygen in an environment where partial pressure of oxygen is low enough to make adult haemoglobin release oxygen.
Helps maximise uptake of oxygen from the mother’s bloodstream.
What are the 3 ways that carbon dioxide are transported?
About 5% is carrier dissolved in the plasma.
10-20% is combined with the amino groups of haemoglobin to form carbaminohaemoglobin.
75-80% is converted to hydrogen carbonate ions in the cytoplasm of red blood cells which then diffuses into the plasma.
What factors affect oxygen dissociation?
Saturation.
Chemical and physical factors such as pH.
What does the Bohr shift describe and how is this shown on a graph?
The affect of high CO2 concentrations on haemoglobin’s affinity for oxygen.
A second line is drawn to the right of and below the standard curve.
How does carbon dioxide affect haemoglobin’s affinity for oxygen?
An increase in CO2 in a tissue, such as during exercise, lowers it’s pH. This lowers the oxygen affinity over all partial pressures, leading to increased release of oxygen where it is needed. This is known as the Bohr shift.
How does temperature affect oxygen dissociation?
A decrease in temps increase haemoglobin’s affinity for oxygen slightly. This means that hypothermia reduces the blood’s ability to release oxygen into metabolising tissue.
Why do large multicellular organisms need a transport system in relation to metabolic rate?
Large multicellular organisms have a high metabolic rate and require high volumes of substances and produce lots of waste. Diffusion alone would not be able to intake and expel all of these substances.
What are the features of a circulatory system for multi-cell animals?
A heart.
A fluid in which substances are transported.
Vessels through which the fluid can flow.
What are the two types of circulatory systems?
Open and closed.
What are the features of an open circulatory system?
It consists of a heart that pumps a fluid called haemolymph through short vessels and into a large cavity called the haemocel.
In the haemocel, the fluid bathes organs and tissues, enabling the diffusion of substances.
When the heart relaxes, the haemolymph is sucked back in via pores called ostia.
Haemolymph moves around the haemocel due to movement of the organism.
What are the limitations with the open circulatory system?
Steep concentration gradients cannot be maintained for efficient diffusion.
The amount of haemolymph flowing cannot be varied to meet changing demands.
What are the features of a closed circulatory system?
Blood is fully enclosed within blood vessels at all times. It doesn’t directly come into contact with cells in the body.
Blood is pumped from the heart through progressively smaller vessels, at the capillaries substances diffuse in and out of the blood and cells.
Blood then returns to the heart via progressively larger vessels.
What are the advantages and disadvantages of a single circulatory system?
Advantages - Less complex
Disadvantages - Low blood pressure, slow movement of blood, Activity levels of the organism tend to be low
What are the advantages and disadvantages of a double circulatory system?
The heart can pump blood further round the body.
High pressure.
Fast flow of blood.
What are the 5 types of blood vessels?
Arteries.
Arterioles.
Capillaries.
Venules.
Veins.
Where do arteries and arterioles carry blood to and from?
Carry oxygenated blood from the heart to the body cells.
Where do veins and venules carry blood to and from?
Carry deoxygenated blood from the body cells to the heart.
What are the 3 components of blood vessels and what are their purpose?
Elastic fibres - Made of elastin, they stretch and recoil providing the vessel with flexibility.
Smooth muscle - Contracts and relaxes changing the size of the lumen.
Collagen - Provides structural support to maintain shape and volume of the vessel.
What is the function of the arteries?
Carry blood away from the heart at high pressure.