Mass Transport 3.3 Flashcards
What is the other / proper name for red blood cells?
Erythrocytes.
What is an erythrocyte?
A red blood cell.
Why is an erythrocyte having a bionconcave shape advantageous?
It provides a larger surface area to volume ratio allowing for the diffusion of oxygen.
Why is an erythrocyte being flat and thin advantageous?
It creates a shorter diffusion pathway for the oxygen to reach all the haemoglobin inside.
What is haemoglobin?
A large protein with a quaternary strucutre which is made up of four polypeptide chains. Its role is to bind to the oxygen to allow the blood to carry it around the body.
What does each chain have within the haemoglobin?
A haem group which contains an iron ion which has the ability to bind to oxygen.
How much oxygen can one hameoglobin molecule bind to?
Four.
Where does oxygen associate with haemoglobin?
In the red blood cells in the capillariesafter the oxygen has diffused from the alveoli and into these capillaries.
What does oxygen associating with haemoglobin form?
Oxyhaemoglobin.
Why is oxygen associating with haemoglobin a reversible reaction?
This is because once they reach respiring cells the oxygen dissociates and leaves haemoglobin.
What is the equation for the reversible reaction of oxygen associating with haemoglobin?
Hb + 4O2 = HbO8
What happens as the partial pressure of oxygen increase?
The haemoglobins affinity for oxygen increases.
What is meant by the term partial pressure?
The partial pressure of a gas is a measure of the concentration of that gas in a mixture of gases or in a liquid. It is based on how much pressure that gas contributes to the overall pressure exerted by the mixture of gases.
What happens if haemoglobins affinty for oxygen is high?
The molecules of haemoglobin will associate with oxygen more easily but dissociate with oxygen less easily.
What happens if haemoglobins affinty for oxygen is low?
The molecules of haemoglobin will associate with oxygen less easily but will dissociate with oxygen more easily.
What type of curve represents the % saturation of haemoglobin to the partial pressure of oxygen?
A sigmoid curve.
Describe the simple structure of haemoglobin.
Quaternary structure, each of the four polypeptide chains
contains a haem group); haem groups each contain an Fe2+ ion.
Why can haemoglobin be described as having quaternary structure?
It is made up of more than one polypeptide chain.
What is the name for oxyhaemoglobin releasing
its oxygen to respiring cells?
Dissociation or unloading.
Where in the body has the highest pO2?
The lungs.
Where does haemoglobin have high affinity for oxygen?
The lungs.
How does increased respiration affect blood pH?
Increased respiration increases pCO2. Carbon dioxide combines with water to form carbonic acid which lowers the pH of blood
Explain how saturation of haemoglobin
affects it’s affinity for oxygen.
The saturation of haemoglobin can also affect its affinity for oxygen. This is because as each oxygen molecule binds it changes the shape of the haemoglobin in a way that makes it easier for further oxygen molecules to bind. However, as the saturation of haemoglobin increases it becomes harder for the final oxygen molecules to bind.
With reference to protein structure, explain how lowering blood pH levels affects haemoglobin.
Lower blood pH means tertiary structure of Hb altered which reduces its affinity for oxygen. More oxygen dissociates.
What is the net result of the Bohr effect?
More oxygen is released where more carbon dioxide is produced in respiration to help maintain metabolic rate
What direction will the dissociation curve shift during the Bohr effect?
To the right.
What is the main difference between foetal haemoglobin and adult haemoglobin?
It has a higher affinity for oxygen than adult haemoglobin
Explain why it is an advantage for
foetal haemoglobin to have a higher affinity than adult haemoglobin.
Makes sure that oxygen leaves mothers blood and enters foetal blood in the placenta.
Give three examples of environments with low oxygen concentrations
Underground, high altitudes, bottom of seabed.
Explain why it is an advantage to have haemoglobin with a higher affinity for oxygen if you live in high altitude environments.
Makes sure that enough O2 is absorbed from the atmosphere as possible so that the organisms can
survive
Explain why it is an advantage to have haemoglobin with a lower affinity for oxygen if you have a larger SA:V.
They will have a higher metabolic rate, so more oxygen is needed to supply increased energy demand.
What are the benefits of a mass
transport system?
Carries raw material from specialised exchange organs to the body cells to remove metabolic waste
Why can’t complex multi cellular
organisms rely on diffusion to transport substances around the body?
They are too large for diffusion to transport substances quickly
enough (small SA:V) as diffusion distance too long.
Define a closed circulatory system.
Blood is enclosed within vessels/diffusion of substances only takes place within vessels.
Define a double circulatory system.
Blood flows through the heart twice for each complete circuit of
the body (i.e simultaneously pumps to lungs and heart)
Maintains a high blood pressure to meet demands of a high
metabolic rate.
Why is a closed circulatory system more efficient?
The blood is forced through fairly narrow tubes so it travels faster and under pressure.
Describe three disadvantages of single circulatory systems, as seen in fish.
Blood pressure drops as blood passes through the gill
capillaries; blood flows slowly through as it is under low
pressure; the rate of delivery of oxygen/nutrients to respiring
tissues is limited (and removal of CO2 and urea)
What is the inner tissue lining of a blood vessel called? What is its role?
Endothelium; reduced friction with the flowing blood.
Describe the three structural layers of an artery.
Thin layer of elastic tissue which allow walls to stretch and recoil (opposes muscle), thick layer of smooth muscle ,thin layer of endothelium.
Describe the stretch
and recoil in arteries.
Heart contracts and blood is forced into the arteries. The elastic walls stretch a little to accommodate the blood. The heart relaxes and the elasticity of the walls causes them to recoil a lot behind the blood pushing it forward. This causes a
pulsing flow through the arteries
What is the role of
arterioles?
Take blood from artery to capillary; they have a layer of smooth muscle which
contracts restricting and slowing blood flow.
Describe how veins are adapted to carry blood back to the
heart.
Wide lumen to ease blood flow; thin layers of elastic/ muscle/ collagen in walls as no need to stretch and recoil; valves to prevent backflow of blood.
Describe how blood flows in
veins.
Blood flow is assisted by the contraction of skeletal muscles during movement of limbs..
Describe the function of a
venule.
Takes blood from the capillaries to the veins.
What is the function of the
capillaries?
Where metabolic exchange occurs so substances are exchanged between cells and the capillaries.
Describe the structure of
capillaries.
Very narrow lumen for short diffusion distance, single layer of cells so it can lie very close to the cells. Joins the arteries and venues together, medium pressure, large surface area.
State the four chambers of the
heart.
Left atria/left ventricle/right atria/right ventricle.
How many circuits are mammal circulatory systems divided into?
Two.
What are the names of the two circuits of the mammal circulatory system?
Pulmonary and systemic.
What is the function of the pulmonary circuit?
It carries deoxygenated blood from the heart to the respiratory surface in the lungs where it is re-oxygenated and then back to the heart.
What is the function of the systemic circuit?
It carris oxygenated blood to all the body’s cells via arteries, and deoxygenated blood back to the heart via veins.
Where does the pulmonary artery carry the blood from?
The heart.
Where does the pulmonary artery carry the blood to?
The lungs.
Where does the pulmonary vein carry the blood from?
The lungs.
Where does the pulmonary vein carry the blood to?
The heart.
Where does the aorta carry the blood from?
The heart.
Where does the aorta carry the blood to?
The body.
Where does the vena cava carry the blood from?
The body.
Where does the vena cava carry the blood to?
The heart.