OESWTE: Mass transport in animals Flashcards
Where does the pulmonary artery carry blood to and from?
To lungs
From heart
Where does the pulmonary vein carry blood to and from?
To heart
From lungs
Where does the aorta carry blood to and from?
To body
From heart
Where does the vena cava carry blood to and from?
To heart
From body
Cardiac muscle is myogenic. What does this mean?
Can contract and relax without nervous or hormonal stimulation.
Give the two ways how cardiac muscle is adapted to its function:
- It is myogenic
- It never fatigues as long as it has a good oxygen supply.
What is the role of coronary arteries?
Supply cardiac muscle with oxygenated blood
What will happen if the coronary arteries become blocked?
- Cardiac muscle wont receive oxygen.
- Cells will be unable to respire and die.
- Myocardial infarction
What is a myocardial infarction?
Heart attack
Why do the atria have thinner muscular walls?
They do not need to contract as hard to pump blood as it is not being pumped far (to ventricles)
Why do the atria have elastic walls?
So they can stretch when blood is entering.
Haemoglobin is made up of _____ polypeptide chains.
Four
Each polypeptide chain in haemoglobin contains an ______.
Iron ion
What gives haemoglobin its red colour?
Its iron ion in each of the four polypeptide chains.
How many oxygen molecules can one human haemoglobin carry?
Four
In the lungs, oxygen joins to haemoglobin to form ________.
Oxyhaemoglobin
Where is oxyhaemoglobin formed?
In the lungs
The formation of oxyhaemoglobin is a ______ reaction.
Reversible
Define loading/association of oxygen:
When an oxygen molecule joins to a haemoglobin and forms oxyhaemoglobin.
Define unloading/disassociation of oxygen:
When an oxygen molecule leaves oxyhaemoglobin.
Define affinity:
The tendency a molecule has to bind with oxygen.
In areas of low partial pressure there is ___________ oxygen available.
Limited
What is the Bohr effect?
When a high carbon dioxide concentration causes the oxyhaemoglobin curve to shift to the right.
In areas of high partial pressure there is ___________ oxygen available.
A lot of
Give an example of an area with a low partial pressure:
Respiring tissues
Give an example of an area with a high partial pressure:
Alveoli
What happens to oxygens in areas of low partial pressure?
Oxygen is offloaded
What happens to oxygen in areas with a high partial pressure?
Oxygen is loaded
As pO2 increases so does _________________.
Hemoglobin’s affinity for oxygen.
The greater the concentration of dissolved oxygen in cells, the _____ the partial pressure.
Higher
Why do the alveoli have a high pO2?
So oxygen will load onto haemoglobin to form oxyhaemoglobin.
When cells respire, they use oxygen- this _____ the pO2.
Lowers
What does an oxygen dissociation curve show?
How saturated the haemoglobin is with oxygen at any given partial pressure.
Where pO2 is high, haemoglobin has a _____ affinity for oxygen, so it has a high affinity for oxygen.
High
Where pO2 is low, haemoglobin has a _____ affinity for oxygen, so it has a low affinity for oxygen.
Low
What shape do oxygen dissociation curves often show?
S-shape
Once the first O2 molecule has joined the haemoglobin, why is it easier for other O2 molecules to join after?
The O2’s shape changes.
As haemoglobin becomes saturated with multiple O2 molecules, it becomes _______ for more O2 molecules to join.
Harder
Haemoglobin gives up its oxygen molecules more readily at _____ pCO2 concentrations.
Higher
When cells respire they produce carbon dioxide, which ____ the pCO2.
Increases
The higher the pCO2, the _____ rate of oxygen offloading.
Higher
When there is a high pCO2 and oxygen offloading, the dissociation curve shifts to the _____.
Right
Organisms that live in environments with a low O concentration have oxygen with a _____ affinity for oxygen.
High
Why do organisms that live in environments with a low O concentration have a high affinity for oxygen?
- There isn’t much oxygen available
- So the haemoglobin has to be very good at loading any available oxygen.
Organisms that are very active and have a high oxygen demand have haemoglobin with a _____ affinity for oxygen.
Lower
Why do organisms that are very active and have a high oxygen demand have haemoglobin with a lower affinity for oxygen?
- They need their haemoglobin to easily unload oxygen so it is available for them to use.
Why do smaller mammals have a lower oxygen affinity?
- Higher SA:V means they lose heat quickly
- Have a higher metabolic rate to maintain body temperature
- Higher metabolic rate means high oxygen offloading demand
Where does the renal artery carry blood to and from?
To kidneys
From body
Where does the renal vein carry blood to and from?
To vena cava
From kidneys
What 3 factors help maintain the high pressure in arteries?
Elastic wall tissue
Folded inner lining
Smaller lumen
Why is the inner lining in the arteries folded?
Allows the artery to stretch
Helps maintain high blood pressure
Arteries divide into smaller vessels called ________.
Arterioles.
How do muscles inside the arterioles allow blood flow to be directed?
They contract to restrict blood flow.
They relax to allow full blood flow.
Arteries maintain a ______ blood pressure.
High
Veins maintain a ______ blood pressure.
Low
Why do veins contain valves?
To prevent the backflow of blood.
Why do veins have a larger lumen than arteries?
They do not need to maintain a high pressure like arteries do.
Arterioles branch into _______.
Capillaries
Why are capillaries always found near cells in respiring tissues?
To allow short diffusion pathway
What is tissue fluid?
Fluid that surrounds cells in tissues.
What is tissue fluid make up of?
Small molecules that leave the blood plasma e.g. oxygen, water.
Why doesn’t tissue fluid contain red blood cells or large proteins?
They are too large to exit the capillary walls.
By which process do substances move out of the capillaries and into the tissue fluid?
Pressure filtration.
At the start of the capillary bed the hydrostatic pressure inside the capillaries is ______ than in the tissue fluid.
Greater
What causes water to re-enter the capillary bed after fluid has been lost?
The water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid.
Role of the right side of the heart:
Pumps deoxygenated blood to the lungs
Role of the left side of the heart:
Pumps oxygenated blood to the whole body
Role of the atrioventricular valves:
Link the atria to the ventricles and stop blood flowing back into the atria when the ventricles contract.
Role of the semi-lunar valves:
Link the ventricles to the pulmonary artery and aorta, and stop blood flowing back into the heart after the ventricles contract
Role of the cords:
Attach the atrioventricular valves to the ventricles to stop them being forced up into the atria when the ventricles contract.
What determines if the valves are open or closed?
Relative pressure of the heart chambers.
What is the impact of higher pressure behind a valve?
It is forced open.
What is the impact of higher pressure in front of a valve?
It is forced shut.
What does it mean if the flow of blood is unidirectional?
It only flows in one direction.
What is the cardiac cycle?
An ongoing sequence of contraction and relaxation of the atria and ventricles.
What are the three stages of the cardiac cycle?
1) Ventricles relax, atria contracts
2) Ventricles contract, atria relaxes
3) Ventricles relax, atria relax
What is an atheroma?
A build-up of fibrous plaque in the endothelium.
How do atheromas form?
- Damage occurs to the endothelium.
- White blood cells, lipids and connective tissue repeatedly clump together under the lining to form fatty streaks
- Fibrous plaque hardens
What is the impact of an atheroma on blood flow?
- Atheroma partially blocks lumen of the artery
- Blood flow is restricted
- Blood pressure increases
What is an aneurysm?
A balloon-like swelling of the artery.
How do aneurysms form?
- Atheroma forms first - damaging the artery.
- Blood traveling at high pressures over a weakened artery push the inner layers through the outer elastic layer.
What is thrombosis?
Formation of a blood clot.
How does thrombosis form?
- Atheroma forms first
- Plaque ruptures the endothelium, damaging the artery and leaving a rough surface
- Platelets and fibrin accumulate at damaged surface and form a blood clot.
The heart muscle is supplied with blood by the _________.
Coronary arteries
What will happen if a coronary artery becomes completely blocked?
- Area of heart muscle will not receive blood supply and consequently no oxygen
- Myocardial infarction will occur
High blood pressure _______ the risk of damage to the artery walls.
Increases
Why does a high blood cholesterol increase the risk of cardiovascular disease?
- Cholesterol is one of the main constitutes in the build up of atheromas.
- Most cardiovascular diseases start with an atheroma.
How does carbon monoxide increase the risk of a heart attack?
- Carbon monoxide binds with haemoglobin and reduces the amount of oxygen transported in the blood
- Consequently reducing the amount of oxygen available to tissues
- Insufficient oxygen supply to the heart can cause a heart attack
Give the 2 ways in which smoking increases the risk of cardiovascular disease:
- Carbon monoxide reduces amount of oxygen transported
- Smoking reduces amount of antioxidants in the blood
Smoking reduces the amount of antioxidants in the blood. Explain how this increases the risk of cardiovascular disease:
- Antioxidants help protect cells from damage
- Fewer antioxidants means cell damage in arteries are more likely.
- Atheromas are more likely to form
