Chapter 7 Flashcards
What structure does haemoglobin have?
Quaternary
What is haemoglobin evolved to do?
Load and unload oxygen under different sets of conditions
How many polypeptide chains does haemoglobin have?
4
What shape does haemoglobin appear to be?
Spherical
What is the process by which oxygen binds to haemoglobin called?
associating or loading
What is the process by which haemoglobin releases its oxygen callled?
Dissociating or unloading
What is the overall role of haemoglobin?
To carry oxygen
In order to fufil its role, haemoglobin has to …
readily associate with oxygen at the surface of the gas exchange site
readily dissociate with oxygen at the tissues requiring it
What is affinity?
Chemical attraction
How does haemoglobin unload and load oxygen at the right conditions?
It changes its affinity for oxygen under different conditions. It achieves this by changing its shape in the presence of CO2. In the presence of CO2, the haemoglobin molecule changes shape to one that has less affinity for oxygen, and therefore it is released
When haemoglobin is exposed to partial pressures of oxygen it…
doesnt bond evenly
In a lower partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
little oxygen bonds to the haemoglobin, and the gradient of the curve is shallow. bc the shape of the molecule makes it difficult for the 1st oxygen molecule to bind to one of the 4 sites of the polypeptide subunits, as they are closely packed.
In a medium partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
The binding of O2 to haemoglobin becomes easier, as the shape of the haemoglobin molecule changes shape on binding with oxygen, making it easier for other molecules to bind to it, and the gradient curve steepens
In a high partial pressure of oxygen, what happens to the saturation of haemoglobin with oxygen? Why?
The binding of the 4th molecule of O2 becomes harder, as it is more difficult to find somewhere to bind to , and the gradient curve levels out
Haemoglobin as a reduced affinity for O2 in the presence of what molecule?
carbon dioxide
The greater the concentration of carbon dioxide, the ___________ the haemoglobin molecule releases the oxygen molecule
more readily
At the gas exchange site, is affinity for oxygen higher or lower and why?
Higher, because concentrations of CO2 are lower as they are diffusing out of the organism, as well as this, there are high levels of O2, and means oxygen is readily associated with haemoglobin
At the respiring tissues, is affinity for oxygen higher or lower and why?
Lower, because concentrations of CO2 are higher as they are being produced during respiration , as well as this, there are low levels of O2, and means oxygen is readily dissociated from haemoglobin
Why does a high concentration of CO2 affect haemoglobin’s affinity for oxygen?
Becase CO2 is acidic when it is dissolved, bonds are broken within haemoglobin that causes a shape change, that enables it to have a lower affinity for oxygen and causes it to unload into respiring cells
Why does a low concentration of CO2 affect haemoglobin’s affinity for oxygen?
In low concentrations of CO2, the gas exchange surface has a slightly higher pH, and this causes the haemoglobin to change shape into one that enables it to load O2 more readily and increases its affinity for haemoglobin so oxygen isnt released in the blood.
In practice, due to atmospheric pressure, how many oxygen molecules bind to haemoglobin?
3
When haemoglobin reaches a tissue with a high respiratory rate, how many oxygen molecules are unloaded?
3
When haemoglobin reaches a tissue with a low respiratory rate, how many oxygen molecules are unloaded?
1
Why do large organisms have transport systems?
Diffusion isnt fast enough to transport all the required substances in and out of large organisms, so specialist exchange surfaces are used to absorb nutrients and respiratory gases and release waste productsq
List 5 features of transport systems
- Have a suitable medium to carry materials
- The transport system transports substances more quickly than diffusion
- Is formed of a closed system with a branching network of wessels
- Has a mechanism for moving substances within the vessel
- Has a mechanism to move substances in 1 direction
What type of circulatory system do mammals have?
Closed double circulatory system where blood is confined to the vessels and passes through the heart twice for each circuit of the body
Why do mammals need a double circulatory system?
Because when blood is passed through the lungs, the pressure is reduced, and if it were to pass to the rest of the body the low pressure would make circulation very slow, by passing the blood through the heart again, pressure is increased and blood is passed through the body very quickly
Do mammals have a high or low metabolic rate?
High
Do mammals have high or low respiratory rates?
High
What is the final method of moving substances from the capillary wall to the cells?
Via diffusion
What are the 2 types of heart chambers?
Atrium and ventricle
Which side of the heart does the deoxygenated blood go in?
right
Which side of the heart does the oxygenated blood go in?
left
List the 4 major vessels
Aorta
Vena Cava
Pulmonary vein
Pulmonary artery
Where is the aorta connected to?
The left ventricle
Where is the Vena cava connected to?
The right atrium
Where is the pulmonary vein connected to?
The left atrium
Where is the pulmonary artery connected to?
The right ventricle
What is the role of the Vena Cava?
Transport deoxygenated blood from body to the heart.
What is the role of the pulmonary artery?
Transport deoxygenated blood from the heart to the lungs
What is the role of the pulmonary vein?
Transport oxygenated blood from the lungs to the heart
What is the role of the aorta?
Transport oxygenated blood from the heart to the body
What are the 2 stages for the beating of the heart?
Systole
Diastole
What is the diastole of the heart?
The relaxation of the heart
What is the systole of the heart?
Contraction of the heart
What is the order of the beating of the heart?
Diastole
Atrial systole
Ventricular systole
What happens to the pressure in the atrium as blood enters?
the pressure increases and exceeds the pressure of the ventricle
What does the increased pressure in the atrium cause happen
The atrioventricular valves open, allowing blood to pass into the ventricles
What happens to the muscular walls of the atria and ventricles when the atrioventricular valves open? What does this cause to happen?
They remain relaxed which causes them to recoil and reduce the pressure in the ventricle, causing it to be lower than the pressure of the atria and pulmonary artery
What happens after the pressure of the ventricle is lower than the pressure of the atria and pulmonary artery?
The semi-lunar valves in the aorta and pulmonary arteries close
What happens after the semi-lunar valves close?
The atria contract to push the remaining blood into the ventricles, while the ventricle walls remain relaxed
What happens are the remaining blood is pushed out of the atria?
The ventricle walls contract simultaneously, increasing the pressure and forcing shut the atrioventricular valves, preventing backflow of blood
What happens after the atrioventricular valves shut after the ventricle walls contract?
The pressure of the ventricle rises further and blood is forced into the pulmonary artery
Blood will always move from a region of _______ pressure to a region of _______
higher
lower pressure
What is the role of valves?
to keep blood flowing in the desirable direction, against the flow of pressure
When do the valves open?
Valves are designed so that they open whenever the difference in blood pressure either side of them favours the movement of blood in the required direction
When do the valves close?
Valves are designed to close whenever blood would tend to flow in the opposite direction of what is desirable
What are the 3 types of valves?
Atrioventricular valves
Semi-lunar valves
Pocket valves
What are atrioventricular valves and what do they do?
The valves between the atriums and ventricles that prevent the backflow of blood when the contraction of the ventricles means that the ventricular pressure exceeds the atrial pressure
What are semi-lunar valves and what do they do?
The valves between the aorta and pulmonary artery. this prevents backflow of blood when the pressure in the vessels exceeds that in the ventricles
What are pocket valves and what do they do?
In the veins throughout the venous system that ensure blood is squeezed back towards the hear and not the other directions
What are valves made out of?
A flap of tough but flexible fibrous tissues shaped like deep bowls
When the pressure is greater on the convex side than the concave side what happens to the valve?
They move apart to let the blood flow
When the pressure is greater on the concave side than the convex side what happens to the valve?
Blood collects within the bowls of the cups which pushes them together and prevents the passage of blood
What is cardiac output?
The volume of blood pumped by 1 ventricle of the heart in 1 minutes
What is cardiac output measured in?
dm3min-1
What is the equation for cardiac output?
Cardiac output= heart rate x stroke volume
what are the blood vessels?
Arteries
Arterioles
Capillaries
veins
What is the basic structure of arteries, arterioles, veins?
- a tough fibrous outer level
- muscle layer
- elastic layer
- inner lining
- lumen
What is the role of a tough fibrous outer level?
resists pressure changes from both the outside and inside
What is the role of a muscle layer?
contracts and controls the flow of blood
What is the role of an elastic layer?
maintain blood pressure by stretching and recoiling
What is the role of the inner lining?
reduce friction and thin to allow diffusion
What is the role of the lumen?
Central cavity that blood flows through
Which out of veins, arteries and arterioles has the thickest muscle layer?
arterioles - thicker even than the arteries because it needs to be able to control the movement of blood into the capillaries
Which out of veins, arteries and arterioles has the thickest elastic layer?
arterioles and arteries
Which out of veins, arteries and arterioles has the biggest lumen?
veins
Do the arteries have valves?
No
Do the veins have valves?
Yes
Do the arterioles have valves?
No
Do the capillaries have valves?
No
What is the role of the artery?
To transport blood rapidly under high pressure from the heart to the tissues
What is the role of the arterioles?
To carry blood under lower pressure than arteries to capillaries from arteries and control the flow of blood between the two
What is the role of the veins?
To transport blood slowly, under low pressure from the capillaries in tissues to the heart
What is the role of the capillaries?
Exchange metabolic materials between the blood and body cells, the flow of blood is much slower so there is time for gas exchange
What is tissue fluid?
A watery liquid that contains glucose, amino acids, fatty acids, oxygen, and ions in solution. It then receives CO2 and other waste materials from the tissues
What is tissue fluid formed from?
Blood plasma
How is tissue fluid formed?
Pumping blood creates hydrostatic pressure at the arterial end of the capillaries, causing tissue fluid to move out of the blood plasma, the holes in it are only small enough to force small molecules out so the cells and proteins dont leave. This kind of filtration is called ultrafiltration.
How is tissue fluid returned to the circulatory system?
once metabolic materials have been exchanged it returns to the circulatory system, mostly via capillaries,.
The loss of tissue fluid from the capillaries reduces the hydrostatic pressure inside of them, and by the time it has reached the venous end, the pressure is lower than that of the pressure outside of the capillaries, so tissue fluid is therefore forced back in by the hydrostatic pressure gradient
What happens to the tissue fluid that cannot be returned to the capillaries?
the remainder is carried back by the lymphatic system.
