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Grice/Hall AQA A-Level Biology Revision Year13 > 3.3.4.1 Mass Transport in Animals > Flashcards

3.3.4.1 Mass Transport in Animals Flashcards

1
Q

What is haemoglobin?

A

It is a group of chemically similar protein molecules

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2
Q

What is the structure of haemoglobin?

A

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

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3
Q

What is the name of the process where oxygen is released from haemoglobin molecules?

A

Unloading or dissociating

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4
Q

What is the name of the process where oxygen binds to haemoglobin molecules?

A

Loading or associating

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5
Q

What must haemoglobin do to be efficient at transporting oxygen?

A

Readily associate with oxygen at the gas exchange surface
Readily dissociate from oxygen at the tissues
These two have to be balanced

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6
Q

How is haemoglobin efficient at transporting oxygen?

A

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

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7
Q

Why are there different haemoglobins?

A

Different affinities of oxygen allow for different uses across the different needs of species which survive in different environmental conditions

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8
Q

What is the oxygen dissociation curve?

A

The graph of the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen

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9
Q

What is the explanation of the oxygen dissociation curve?

A
  1. shape makes first oxygen molecule hard to bind, at low oxygen concentrations the gradient is shallow
  2. first binding oxygen changes the molecule shape, this makes it easier for three extra oxygen molecules
  3. positive cooperativity where it takes a smaller increase in partial pressure for the 2nd oxygen to bind, gradient of the curve steepens
  4. after 3rd binding, binding site is harder to find because of probability, gradient reduces, graph flattens off
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10
Q

How can different oxygen association curves be interpreted?

A

The further left it is, the greater the affinity for oxygen so it loads readily but unloading isn’t as easy
And vice versa

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11
Q

What is partial pressure?

A

The pressure that the amount of gas contributes to the total pressure of the gas mixture
Measured in kiloPascals

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12
Q

How is haemoglobin affected at the gas exchange surface?

A

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

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13
Q

How is haemoglobin affected at rapidly respiring tissues?

A

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

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14
Q

Why does an increased CO2 concentration cause the release of oxygen?

A

Dissolved CO2 is acidic and low pH cause haemoglobin to change shape

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15
Q

What is the process for loading, transport and unloading of oxygen by haemoglobin?

A

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

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16
Q

What is the relationship between the activeness of a tissue and the loading, transport and unloading of oxygen by haemoglobin?

A

The more active a cell is, the more oxygen is unloaded

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17
Q

What is the mammalian system of transport?

A

A mass transport system due to the large distances

Specialist exchange surfaces to absorb nutrients and respiratory gases and remove excretory muscles

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18
Q

What are the common features of the mammalian transport system?

A

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

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19
Q

How do mammals move the transport medium within vessels?

A

Muscular contraction, either of body muscles or a specialised pumping organ

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20
Q

What is the type of circulation system that a mammal has?

A

Closed, double circulatory system

Blood is confined to vessels and passes twice through the heart for each complete circuit of the body

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21
Q

Why does a mammal need a double circulation system?

A

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

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22
Q

Why do mammals need a fast circulation system?

A

They have a high metabolism which is why substances need to be transported quickly

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23
Q

Why is the final exchange from blood vessels rapid?

A

A large surface area
Short distances
A steep diffusion gradient

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24
Q

Which side of the heart deals with which type of blood?

A

Left side deals with oxygenated blood from the lungs

Right side deals with deoxygenated blood from the body

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25
What is the atrium?
Thin walled, elastic, stretches, collects blood
26
What is a ventricle?
Contracts strongly to pump blood, has a much thicker muscular wall
27
What does the right ventricle do?
It pumps blood to the lungs | Has a thinner muscular wall than the left
28
What is the timing of the atria and ventricles?
Atria contract together | Ventricles contract together
29
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
30
What is the name of the vessels which connect the heart to the lungs?
Pulmonary vessels
31
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
32
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
33
What does the pulmonary vein do?
It brings oxygenated blood back from the lungs | It is connected to the left atrium
34
What are the two phases of the cardiac cycle?
Contraction (systole) and relaxation (diastole)
35
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
36
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 ```
37
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
38
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 ```
39
What is the function of valves?
They prevent the backflow of blood
40
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
41
Where are semi-lunar valves found? | What is their function?
In the aorta and pulmonary artery They prevent the backflow of blood into the ventricles when the pressure in these vessels exceeds that in the ventricles Arrives when the elastic walls of the vessel recoil increasing the pressure within them and when the ventricle walls relax reducing the pressure within ventricles
42
What are pocket valves?
They occur throughout the venous system | They ensure that when veins are squeezed, blood flows back towards the heart rather than away from it
43
What is the structure of valves?
A number of cusp-shaped flaps | Made of tough, flexible, fibrous tissue
44
How do valves work?
When pressure is greater on the convex side of these cups, rather than on the concave side, they move apart to let blood pass between the cusps When pressure is greater on the concave side than the convex side, blood collects within the 'bowl' of the cusps, this pushes them together to form a tight fit that prevents the passage of blood
45
How do you work out cardiac output? (plus units)
Cardiac output = stroke volume X heart rate Cardiac output = dm3 min-1 Stroke volume = volume put out with each contraction in dm3 Heart rate = number of beats per minute
46
What is the function of arteries?
They carry blood away from the heart and into arterioles
47
What is the function of arterioles?
They are smaller arteries that control blood flow from arteries to capillaries
48
What is the function of capillaries?
They are tiny vessels that link arterioles to veins
49
What is the function of veins?
They carry blood from capillaries back to the heart
50
What are the differences between the structure of blood vessels?
The proportions of each layer
51
What is hydrostatic pressure in terms of tissue fluid?
The pressure created by the heart pumping at the ends of the capillaries It causes tissue fluid to move out of the blood plasma
52
What is the structure of the heart?
See card
53
What is the heart?
A muscular organ that lies in the thoracic cavity behind the sternum (breastbone) It operates continuously and tirelessly throughout the life of an organism
54
What is the structure of the heart? (No explanation)
``` Left and right atrium Left and right atrioventricular valve Aorta Vena cava Pulmonary artery Pulmonary vein ```
55
Why are there two separate pumps in the heart?
Mammals have a system where the blood is returned to the heart to increase its pressure before it is redistributed to the rest of the body It is essential to keep the oxygenated blood separate from the deoxygenated blood
56
What are the vessels connected to the four chambers of the heart? (No explantion)
Aorta Vena cava Pulmonary artery Pulmonary vein
57
What is the vena cava?
Connected to the right atrium | Brings deoxygenated blood back from the tissues of the body except the lungs
58
How is the heart supplied with oxygen?
Heart muscle is supplied by it's own blood vessels called the coronary arteries These branch off the Aorta shortly after it leaves the heart
59
What is myocardial infarction?
Blockage of coronary arteries Because an area of the heart muscle is deprived of blood and oxygen, the muscle cells are unable to respire aerobically and die
60
What are the types of blood vessels? (No explanation)
Arteries Arterioles Capillaries Veins
61
What are the layers of blood vessels? (No explanation)
``` Tough fibrous outer layer Muscle layer Elastic layer Thin inner lining (endothelium) Lumen ```
62
What is the function of the tough fibrous outer layer in blood vessels?
Resists pressure changes from both within and outside the vessel
63
What is the function of the muscle layer in blood vessels?
Can contract and so control the flow of blood
64
What is the function of the elastic layer in blood vessels?
Helps to maintain blood pressure by stretching and springing back (recoiling)
65
What is the function of the thin inner lining in blood vessels?
Smooth to reduce friction | Thin to allow diffusion
66
What is the lumen of blood vessel?
The central cavity of the blood vessel through which the blood flows
67
What are the differences between arteries and arterioles?
Arterioles are smaller in diameter and have a relatively larger muscle layer and lumen
68
What is the structure of arteries in comparison to other blood vessels? (No explanation)
Muscle layer is thick compared to veins Elastic layer is thick compared to veins Overall thickness of the wall is great No valves
69
How does the muscle layer of arteries relate to it's function?
Muscle layer is thick compared to veins | Smaller arteries can be dilated and constricted to control the volume of blood
70
How does the elastic layer of arteries relate to it's function?
Elastic layer is relatively thick compared to veins As it is important for blood pressure to be high to reach extremities Elastic wall is stretched at systole and springs back at diastole Stretching and recoiling helps to maintain high pressure and smooth pressure surges created by the heart
71
How does the overall thickness of the walls of arteries relate to their function?
This resists the vessel bursting under pressure
72
How does the lack of valves of arteries relate to their function?
Because blood is under constant high pressure due to the heart pumping, blood tends not to flow backwards Valves are only found in arteries leaving the heart
73
What is the structure of arterioles in relation to other blood vessels? (No explanation)
Muscle layer is relatively thicker than in arteries | Elastic layer is relatively thinner than in arteries
74
How does the muscular layer in arterioles relate to their function?
Muscle layer is thicker than in arteries The contraction of the muscle layer allows construction of the lumen which restricts blood flow and so control movement into the capillaries which supply tissues with blood
75
How does the elastic layer in arterioles relate to their function?
Thinner than in arteries because the blood pressure is lower
76
What is the structure of veins in relation to other blood vessels? (No explanation)
Muscle layer is thin compared to arteries Elastic layer is thin compared to arteries Overall thickness of the wall is small Has valves at intervals throughout
77
How does the muscular layer in veins relate to their function?
Thin compared to arteries | Veins carry blood away from tissues and so their constriction and dilation cannot control the flow of blood to tissues
78
How does the elastic layer in veins relate to their function?
Thin compared to arteries | Low pressure of blood will not cause them to burst and is too low to create a recoil action
79
How does the overall wall thickness in veins relate to their function?
Small overall thickness Pressure in the veins is too low to create a bursting risk Allows them to be flattened easily so aids the flow of blood within them
80
How do the valves in veins relate to their function?
Valves occur at intervals throughout This ensures that blood does not flow backwards Blood pressure is so low that without valves, blood might flow backwards
81
How do valves work?
Blood can flow easily through one side of a valve If blood flows form the opposite direction, the valves are pushed closed and blood is prevented from flowing any further in this direction
82
What is the structure of capillaries in relation of other blood vessels? (No explanation)
``` Walls mostly consist of the lining layer Numerous and highly branched Narrow diameter Lumen is narrow Spaces between the lining (endothelial cells) ```
83
How does the lining layer in capillaries relate to their function?
Mostly made of the lining layer Makes them extremely thin to reduce diffusion distance This allows for rapid diffusion between the blood and the cells
84
How does the capillaries being numerous and highly branched relate to their function?
Provide a large surface area for exchange
85
How does the capillaries having a narrow diameter relate to their function?
Can permeate tissues | No cell is far from a capillary so there is a short diffusion pathway
86
How does the capillaries having a narrow lumen relate to their function?
Red blood cells are squeezed flat against the side of the capillary Brings them even closer to the cells to which they supply oxygen Reduces diffusion distance
87
How does the capillaries having spaces between the lining cells relate to their function?
Allows white blood cells to escape in order to deal with infections within tissues
88
Why is tissue fluid needed?
Capillaries cannot serve every single cell directly | The final journey of metabolic materials is made in tissue fluid which bathes the tissues`
89
What is the function of arteries?
To transport blood rapidly under high pressure from the heart to the tissues
90
What is the function of arterioles?
To carry blood under lower pressure than arteries from arteries to capillaries They control the flow of blood between the two
91
What is the function of veins?
Transport blood slowly under low pressure from the capillaries in tissues to the heart
92
What is the function of capillaries?
To exchange metabolic materials such as oxygen, CO2 and glucose between the blood and the cells of the body Flow of blood in the capillaries is much slower which allows for the exchange of materials
93
What is tissue fluid?
A watery liquid that contains glucose, amino acids, fatty acids, ions in solution and oxygen It supplies all these substances to the tissues Receives CO2 and waste from the cells
94
How is tissue fluid formed?
Process called ultrafiltration Pumping by the heart cause blood to move into smaller vessels which increases hydrostatic pressure at the ends of the capillaries This pressure causes tissue fluid to move out of the blood plasma Outward pressure is opposed by: Hydrostatic pressure of the tissue fluid outside the capillaries which resists outward movement of liquid The lower water potential of the blood due to plasma proteins which causes water to move back into the blood within the capillaries Combined pressure creates an overall pressure which pushes tissue fluid out of the capillaries at the arterial end Cells and protein in the blood are too large to cross membranes so stay in the blood
95
How is tissue fluid normally returned to the circulatory system?
Loss of tissue fluid from capillaries reduces the hydrostatic pressure inside them At the venous end of the capillary network, the hydrostatic pressure is lower than the tissue fluid Therefore tissue fluid is moved back into the capillaries Plasma has lost water and contains proteins so has a lower water potential than the tissue fluid Water leaves by osmosis down a water potential gradient Tissue fluid has gained CO2 and waste but lost nutrients and oxygen to the cells
96
Where are the two pathways for tissue fluid?
Not all tissue fluid can return to capillaries Remainder is carried back via the lymphatic system This is a system of vessels that being in the tissues Similar to capillaries but merge into a larger vessel network Vessels drain their contents into the bloodstream via two ducts that join veins close to the heart
97
How are the contents of the lymphatic system moved?
Hydrostatic pressure: of the tissue fluid that has left the capillaries Contraction of body muscles: squeezes lymph vessels, valves ensure that fluid moves towards the heart and away from tissues
98
What are the processes involved in the lymph system? (No explanation)
Tissue fluid moves out of blood plasma via ultrafiltration Tissue fluid moves into blood plasma by reabsorption Tissue fluid moves into lymph by drainage Lymph is returned via lymph vessels to blood plasma
99
What is diastole?
Relaxation of the heart
100
What is systole?
Heart muscle contracts Atrial systole: atria contract Ventricular systole: ventricles contract

Grice/Hall AQA A-Level Biology Revision Year13 (60 decks)

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