B7 Mass Transport Flashcards
(134 cards)
1
Q
What are the thick muscular walls of the heart called
A
Cardiac muscle
2
Q
What are the uniques properties of the cardiac muscle
A
• It is myogenic, meaning it can contract and relax without nervous or hormonal stimulation
• It never fatigues, as long as it have a supply of oxygen
3
Q
What do the coronary arteries do
A
Supply cardiac muscle with oxygenated blood
4
Q
Where are the coronary arteries
A
They branch of from the aorta
5
Q
What happens if the coronary arteries become blocked
A
If they become blocked cardiac muscle won’t receive oxygen, therefore will not be able to respire and the cells will die.
This results in myocardial infarction (a heart attack)
6
Q
What are the 4 chambers of the Heart
A
Left atrium
Right atrium
Left ventricle
Right ventricle
7
Q
What are the atria
A
Thinner muscular walls.
Do not need to contact as hard as not pumping blood far (only to ventricles)
Elastic walls to stretch when blood enters
8
Q
What are the ventricles
A
Thicker muscular walls to enable Right pulmonary arteries, bigger contraction.
This creates a higher blood pressure to enable blood to flow longer distances (to the lungs and the rest of the body)
9
Q
What does the right ventricle do and how is it adapted for its function
A
Pumps blood to the lungs.
This needs to be at a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange
Therefore, thinner muscular wall in comparison to the left ventricle
10
Q
What does the left ventricle do and how is it adapted for its function
A
Pumps blood to the body. This needs to be at a higher pressure to ensure blood reaches all the cells in the body.
Therefore, much thicker muscular wall in comparison to the right ventricle to enable larger contractions of the muscle to create higher pressure.
11
Q
What does pulmonary refer to
A
The lungs
12
Q
What does the vena cave do
A
(Means body vein) Carries deoxygenated blood from the body into the right atrium
13
Q
What does the pulmonary vein do
A
Carries oxygenated blood from the lungs to the left atrium
14
Q
Do veins carry blood away or towards the heart
A
Veins IN to the heart
15
Q
Do arteries carry blood towards our away from the heart
A
A away from the heart
16
Q
What does the pulmonary artery do
A
Carries deoxygenated blood from the right ventricle to the lungs to become oxygenated
17
Q
What does the aorta do
A
Carries oxygenated blood from the left ventricle to the rest of the body
18
Q
Where are the semi lunar valves
A
In aorta and pulmonary artery
19
Q
Where are the atrioventricluar valves
A
Between atria and ventricles
Bicuspid (left side)
Tricuspid (right side)
20
Q
What do valves do
A
Prevent backflow of blood
21
Q
What doe the valves do when pressure is higher/lower
A
Open when pressure is higher behind the valve.
Close when pressure is higher in front of the valve
22
Q
What is the septum and what does it do
A
Separates the deoxygenated and oxygenated blood
Maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiring cells.
23
Q
How many stages is the cardiac cycle
A
3
24
Q
What are the 3 stages of the cardiac cycle
A
Diastole
Atrial systole
Ventricular Systole
25
What happens in Diastole
The atria and ventricular muscles are relaxed
This is when blood will enter the atria via the vena cava and pulmonary vein.
The blood flowing into the atria increases the pressure within the atria
26
What happens in atrial systole
The atria muscular walls contract, increasing the pressure further.
This causes the atrioventricular valves to open and blood to flow into the ventricles.
The ventricular muscular walls are relaxed
(ventricular diastole)
27
What happens in ventricular systole
After a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria.
This causes the atrioventricular valves to close and the semi-lunar valves to open.
The blood is pushed out of the ventricles into the arteries (pulmonary and aorta)
28
What is the cardiac output
The volume of the blood which leaves one ventricle in one minute is the cardiac output.
29
What is the equation for cardiac output
Cardiac output = heart rate X stroke volume
30
What is heart rate
Beats of the Heart per minute min-1
31
What is the stroke volume
Volume of blood that leaves the heart each beat dm3
32
When do atrioventricular valves open
Atriventricular valves open when the pressure is higher in the atria compared to the ventricles.
33
When do atrioventricular valves close
They close when the pressure is higher in the ventricles compared to the atria
34
When do semi-lunar valves open
Semi-lunar valves open when the pressure is higher in the ventricle compared to the arteries (pulmonary artery or aorta).
35
When do semi-lunar valves close
They close when the pressure is higher in the arteries compared to the ventricles
36
How do the valves ensure blood flow is unidirectional
The pressure and volume changes within each chamber of the heart cause the valves to open and close which ensures blood flow is unidirectional.
37
Why is it useful to represent pressure and volume changes within the heart on a graph
These pressure and volume changes can been represented on graphs to make it possible to identify when the valves open/close during the cardiac cycle
38
Describe the mechanism by which an arteriole regulates blood flow to capillaries. (2 marks)
The smooth muscle within the arteriole contracts.
This contraction leads to the narrowing or constriction of the arteriole lumen.
39
Which blood vessel transports blood at the lowest pressure: capillary, pulmonary vein, renal vein, vena cava
Vena cava
40
Describe the function of the coronary arteries.
(2 mark)
(Carry) oxygen / glucose
(To) heart muscle
41
Name the blood vessel that carries deoxygenated blood from the body into the heart. (1 mark)
Vena cava
42
Name the blood vessel that carries blood from the heart to the kidneys. (1 mark)
Renal artery
43
Suggest why there are larger fluctuations in blood pressure in the aorta than in the small arteries.(3 marks)
1. Aorta is close to the heart
2. (Aorta has) elastic tissue;
3. (Aorta has) stretch/recoil.
44
Explain how the heart contributes to the formation of tissue fluid. (2 marks)
1. Contraction of ventricle(s) produces high blood / hydrostatic pressure;
2. (This) forces water (and some dissolved substances) out (of blood capillaries);
45
Suggest how might a lymphatic system obstruction lead to the development of lymphoedema, a condition characterised by swelling in the legs. (1 mark)
Excess tissue fluid cannot be (re)absorbed / builds up
46
Explain why individuals with significantly elevated ventricular blood pressure experience the build up of tissue fluid outside their blood capillaries? (2 marks)
1. More fluid forced/filtered out of capillary/blood (due to high pressure);
2. Less return of fluid (into capillary/blood) due to pressure
OR
Lymph(atic) (system) cannot drain away all excess fluid;
47
Suggest how does the dilation of blood vessels, induced by certain medications aimed at lowering high ventricular blood pressure, lead to a reduction in ventricular blood pressure? (2 mark)
1. Larger lumen/volume (of blood vessels);.
2. Reduces (blood) pressure (in blood vessels);
3. Less friction/resistance (in blood vessels)
48
In an individual with normal cardiovascular function, blood flows unidirectionally through the heart. Give two ways by which this directional flow is maintained.(2 marks)
1. Pressure gradient / moves from high to low pressure;
2. Valves stop backflow;
49
The aorta has structural features adapted to is function. State four of the structural features and explain how they relate to its function. (4 marks)
1. Elastic tissue to allow stretching smoothes outflow of blood;
2. (Elastic tissue) stretches when ventricles contract
3. Muscle for contraction;
4. Thick wall withstands pressure;
5. Smooth endothelium reduces friction;
6. Semi-lunar valve prevents backflow.
50
What’s is the circulatory system in mammals
Closed, double circulatory system
51
Why’s the circulatory system in mammals closed
the blood remains within the blood vessels.
52
Why’s the circulatory system in mammals double
the blood passes through the heart twice in each circuit.
There is one circuit which delivers blood to the lungs and another circuit which delivers blood to the rest of the body.
53
Why do mammals require a double circulatory system
To manage the pressure of blood flow
54
Why does the blood flow through the lungs at a lower pressure
The blood flows through the lungs at a lower pressure. This prevents damage to the capillaries in the alveoli and also reduces the speed at which the blood flows, enabling more time for gas exchange.
55
What happens to the oxygenated blood from the lungs in the double circulatory system
The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that the blood reaches all the respiring cells in the body.
56
What are the major blood vessels in the circulatory system
The coronary arteries and the following blood vessels attached to these organs:
•Heart (vena cava, aorta, pulmonary artery and pulmonary vein)
• Lungs (pulmonary artery and pulmonary vein)
•Kidneys (Renal artery and renal vein)
57
How are the major blood vessels connected within the circulatory system
These major blood vessels are connected within the circulatory system via the arteries, arterioles, capillaries and veins.
58
What do arteries do
Arteries carry blood Away (hint to remember -A Away) from the heart and into arterioles.
59
How are the blood vessels linked in the circulatory system
Arteries carry blood Away (hint to remember
-A Away) from the heart and into arterioles.
The arterioles are smaller than arteries and connect to the capillaries.
The capillaries connect the arterioles to the veins.
The veins carry blood back into the heart (hint to remember- velNs carry blood IN).
60
Properties of arteries
Muscle layer = Thicker than veins so that constriction and dilation can occur to control volume of blood.
Elastic layer = Thicker than veins to help maintain blood pressure. The walls can stretch and recoil in response to the heart beat.
Wall thickness = Thicker wall than veins to help prevent the vessels bursting due to the high pressure.
Valves =no
61
Properties of arterioles
Muscle layer = Thicker than in arteries to help restrict blood flow into the capillaries.
Elastic layer = Thinner than in arteries as the pressure is lower
Wall thickness = Thinner as pressure is slightly lower.
Valves = no
62
Properties of veins
Muscle layer = Relatively thin so it cannot control the blood flow.
Elastic layer = Relatively thin as the pressure is much lower.
Wall thickness = Thin as the pressure is much lower so there is low risk of bursting. The thinness means the vessels are easily flattened, which helps the flow of blood up to the heart.
Valves = yes
63
Properties of capillaries
Muscle layer = no muscle layer
Elastic layer = no elastic layer
Wall thickness = One cell thick consisting of only a lining layer. This provides a short diffusion distance for exchanging materials between the blood an cells.
Valves = no
64
Tracers - investigating translocation
involves radioactively labelling C
Plants provided with only radioactively labelled carbon dioxide, over time this’s absorbed into plant and used in photosynthesis to create sugars which all contain radioactively labelled carbon.
Thin slices from stems then cut and placed on x-ray film that turns black when exposed to radioactive material.
When stems are placed on x-ray film section of stem containing the sugars turn black, and this highlights where phloem are and shows sugars are transported in phloem.
65
Ringing experiment - investigating translocation
A ring of bark and phloem are peeled and removed off a tree trunk. The result of removing the phloem is that the trunk swells above the removed section.
Analysis of the liquid in this swelling shows it contain sugar.
This shows that when the phloem is removed, the sugars cannot be transported and therefore proves the phloem transports sugars.
66
Translocation (1) - How sucrose transports from the source to the sieve tube element
Photosynthesis occurring in the chloroplasts of leaves creates organic substances, e.g. sucrose.
• This creates a high concentration of sucrose at the site of production, therefore sucrose diffuses down its concentration gradient into the companion cell via facilitated diffusion.
• Active transport of H+ occurs from the companion cell into the spaces within the cell walls using energy.
• This creates a concentration gradient and therefore the H+ move down their concentration gradient via carrier proteins into the sieve tube elements.
• Co-transport of sucrose with the H+ ions occurs via protein co-transporters to transport the sucrose into sieve tube element.
67
Translocation (2) - Movement of sucrose within the phloem sieve tube element
The increase of sucrose in the sieve tube element lowers the water potential.
• Water enters the sieve tube elements from the surrounding xylem vessels via osmosis.
• The increase is water volume in the sieve tube element increase the hydrostatic pressure causing the liquid to be forced towards the sink.
68
Translocation (3) - Transport of sucrose to the sink (respiring cells)
• Sucrose is used in respiration at the sink, or stored or stored as insoluble starch.
• More sucrose is actively transported into the sink cell, which causes the water potential to decrease.
• This results in osmosis of water from the sieve tube element into the sink cell (some water also returns to the xylem).
• The removal of water decreases theolume in the sieve tube element and therefore the hydrostatic pressure decreases.
• Movement of soluble organic substances is due to the difference in hydrostatic pressure between the source and sink end of the sieve tube element.
69
What’s the Mass transport of organic substances in plants is known as
Translocation
70
Whats the Mass transport of organic substances (sucrose) in plants from source to sink is due to
a hydrostatic pressure gradient in the sieve tube element.
71
How is the hydrostatic pressure created
is created by the active transport of sucrose into the sieve tube element, creating lowering the water potential so water moves in by osmosis.
72
What experiments can be used to investigate the transport or organic substances in plants.
Tracers and ringing experiments
73
What gas diffuses out of the stomata
Oxygen
74
What gas diffuses in through the stomata
Carbon dioxide
75
What do stomata do to reduce water loss by evaporation
To reduce water loss by evaporation, stomata close at night when photosynthesis wouldn't be occurring.
76
What are xerophytic plants
Xerophytic plants are adapted to survive in environments with limited water.
They have structural features to enable efficient gas exchange to occur whilst also limiting the water loss.
77
Xerophyte adaptations
Curled leaves to trap moisture to increase local humidity
Hairs to trap moisture to increase local humidity
Sunken stomata to trap moisture to increase
Thicker cuticle to reduce evaporation
Longer root network to reach more water.
78
What’s transpiration
The loss of water vapour from the stomata by evaporation.
79
What are 4 factors that affect transpiration
Light intensity
(Positive correlation - More light causes more stomata to open = larger surface area for evaporation)
Temperature
(Positive correlation - More heat means more kinetic energy, faster moving molecules and therefore more evaporation)
Humidity
(Negative correlation - More water vapour in the air will make the water potential more positive outside of the leaf, therefore reduces the water potential gradient.)
Wind
(Positive correlation - More wind will blow away humid air containing water vapour, therefore maintaining the water potential gradient.)
80
Movement of water up the xylem
Water moves up a plant from the roots against gravity. This could be several metres against gravity in large trees!
81
How is the MOVEMENT OF WATER UP THE XYLEM possible
Cohesion-tension theory
+ Cohesion
+ Capillarity — adhesion
+ Root Pressure
82
Why is cohesion possible in water
Water is a dipolar molecule (slight negative oxygen and slight positive hydrogens.
This enables hydrogen bonds to form between the hydrogen and oxygen of different water molecules.
This creates cohesion between water molecules - they stick together. Therefore water travels up the xylem as a continuous water column.
HB hold together water molecules (cohesion)
83
Capillarity
Adhesion of water is when water sticks to other molecules. Water adheres to the xylem walls.
The narrower the xylem the bigger the impact of capillarity.
84
Root pressure
As water moves into the roots by osmosis it increases the volume of liquid inside the root and therefore the pressure inside the root increases.
This is known as root pressure.
This increase in pressure in the roots forces water above it upwards (positive pressure).
85
Process of movement of water up the xylem
I. Water vapour evaporates out of stomata on leaves. This loss in water volume creates a lower pressure.
2. When this water is lost by transpiration more water is pulled up the xylem to replace it (moves due to negative pressure).
3. Due to the hydrogen bonds between water molecules, they are cohesive (stuck together). This creates a column of water within the xylem.
4. Water molecules also adhere (stick) to the walls of the xylem. This helps to pull the water column upwards.
5. As this column of water is pulled up the xylem it creates tension, pulling the xylem in to become narrower.
86
What are the 2 key cells that the phloem tissue contains
I. sieve tube elements
2. companion cells
87
What are sieve tube elements
Living cells
Contain no nucleus
Contain fencorganelles
88
What is a Companion cells
Provide ATP required for active transport of organic substances
89
What is the transport of organic substances in a plant
Requires energy - active (co-transport)
90
Source to sink explanation
Sucrose lowers water potential of source cell.
Water enters by osmosis - This increases the hydrostatic pressure in the source cell
Respiring cell is using up sucrose, and therefore it has a more positive water potential. Water leaves the sink cell by osmosis - This decreases the hydrostatic pressure in the sink cell
The source cell has a higher hydrostatic pressure than the sink cell, so the solution is forced towards the sink cell via the phloem.
91
What is haemoglobin
Haemoglobins are groups of proteins found in different organisms.
protein with quaternary structure.
Haemoglobin and red blood cells transport of oxygen
92
What is Affinity of haemoglobin for oxygen
The ability of haemoglobin to attract, or bind, oxygen
93
What is the Saturation of haemoglobin with oxygen
When haemoglobin is holding the maximum amount of oxygen it can bind
94
What is the Loading / association of haemoglobin
binding of oxygen to haemoglobin
95
What is the Unloading dissociation of haemoglobin
When oxygen detaches, or unbinds, from haemoglobin
96
OXYHAEMOGLOBIN DISSOCIATION CURVE
Oxygen is loaded in regions with a high partial pressure of oxygen (e.g. alveoli) and is unloaded in regions of low partial pressure of oxygen (e.g. respiring tissues). This is shown on the oxyhaemoglobin dissociation curve.
97
COOPERATIVE BINDING
The cooperative nature of oxygen binding to haemoglobin is due to the haemoglobin changing shape when the first oxygens binds. This then makes it easier further oxygens to bind.
98
What is the Bohr effect?
The Bohr effect is when a high carbon dioxide concentration causes the oxyhemoglobin curve to shift to the right. The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of haemoglobin slightly.
99
Why do animals have different types of haemoglobin
Animals have different types of haemoglobin which have different affinities for oxygen, which is an adaptation to their environments.
100
What are some examples of organisms with different types of haemoglobin
Llama - Llamas live at high altitudes where there is a lower partial pressure of oxygen.
Dove - Faster metabolism, so needs more oxygen for respiration to provide energy for contracting muscles
Earthworm - Underground there is lower a partial pressure of oxygen
101
Describe the structure of haemoglobin
Globular
Water soluble
Consists of 4 polypeptide chains, each carrying a haem group (quaternary structure)
102
Describe role of haemoglobin
Present in rbc
Oxygen molecules bind to haem groups and are carried around body to where they’re needed in respiring tissues
103
Name 3 factors affecting oxygen-haemoglobin binding
1. partial press/conc of oxygen
2. partial press/conc of CO2
3. Saturation of haemoglobin with oxygen
104
How does partial pressure of oxygen affect oxygen-haemoglobin binding
As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin.
When partial pressure is low, oxygen is released from haemoglobin
105
How does partial pressure of CO2 affect oxygen-haemoglobin binding
As partial press of CO2 increases, conditions become acidic causing haemoglobin to change shape.
Affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin
This is known as Bohr effect
106
How does saturation of haemglobin with affect oxygen-haemoglobin binding
It’s hard for 1st oxygen molecule to bind
Once it does, it changes the shape to make it easier for 2nd and 3rd mole ones to bind - known as positive cooperativity
It’s then slightly harder for 4th oxygen molecule to bind because there’s a low chance of finding a binding site
107
Explain why oxygen binds to haemoglobin in lungs
Partial press of O2 is high
Low conc of CO2 increases lungs, so affinity is high
Positive cooperativity ( after 1st O2 molecule binds, binding of subsequent molecules is easier)
108
Explain why oxygen is released from haemoglobin in respiring tissues
Partial press of O2 is low
High conc of CO2 increases lungs in respiring tissues, so affinity decreases
109
What do oxyhaemoglobin dissociation curves show
Saturation of haemoglobin with Oxygen (in %), plotted against partial pressure of oxygen (in kPa).
Curves further to left show haemoglobin has higher affinity for oxygen
110
How does CO2 affect the position of an oxyhaemoglobin dissociation curve
Curve shifts to right because haemoglobin’s affinity for oxygen has decreased
111
Name some common features of a mammalian circulatory system
1. Suitable medium for transport, water based to allow substances to dissolve
2. Means of moving medium and maintaining pressure throughout body, such as heart
3. Means of controlling flow so it remains unidirectional, such as valves
112
Relate structure of heart chambers to their function
Atria = thin walled, elastic, so they can stretch when filled with blood
Ventricles = thick muscular walls pump blood under high blood pressure. The left ventricle is thicker than right because it has to pump blood all the way around the body
113
Relate structure of blood vessels to their function
Arteries = thick walls to handle high pressure without tearing, and are muscular and elastic to control blood flow
Veins = thin walls due to lower pressure, therefore requiring valves to ensure blood doesn’t flow backwards. Have less muscular and elastic tissue as they don’t have to control blood flow.
114
Why are 2 pumps (left and right) needed instead of one
To mantain blood pressure around the whole body.
When blood passes though narrow capillaries of lungs, pressure drops sharply and therefore wouldn’t be flowing strongly enough to continue around whole body.
Therefore it’s returned to heart to increase pressure
115
Describe what happens during cardiac diastole
Heart is relaxed
Blood enters atria, increasing pressure and pushing open the atrioventricular valves.
This allows blood to flow into ventricles.
Pressure in heart is lower in the arteries, so semilunar valves remain closed
116
Describe what happens during atrial systole
Atria contract, pushing any remaining blood into ventricles
117
Describe what happens during ventricular systole
Ventricles contract, press increases, closing atrioventricular valves to prevent backflow, and opening the semilunar valves.
Blood floes into arteries
118
Name nodes involved in heart contraction and where they’re situated
SAN = wall of right atrium
AVN = in between 2 atria
119
What does myogenic mean
The Hearts contraction is initiated from Within muscle itself, rather than by nerve impulses
120
Explain how heart contracts
SAN initiates + spreads impulse across atria, so they contract
AVN receives, delays, and then conveys the impulse down bundle of HIS
Impulse travels into purkinje fibres which branch across ventricles, so they contract from bottom up.
121
Why does impulse need to be delayed
If impulse spread straight from atria into ventricles, there would not be enough time for all blood to pass through and for valves to close
122
How’s structure of capillaries suited to their function
Walls are only 1 cell thick; short diffusion pathway
Very narrow, so can permeate tissues and rbc can lie flat against wall, effectively delivering oxygen to tissues
Numerous & highly branched, providing a large SA
123
What’s tissue fluid
A watery substance containing glucose, amino acids, oxygen, and other nutrients
It supplies these to cells, while also removing any waste materials
124
How’s tissue fluid formed
As blood is pumped through increasingly small vessels, this creates hydrostatic pressure which forces fluid out of capillaries.
It bathes the cells, and then returns to capillaries when hydrostatic pressure is low enough
125
How’s water transported in plants
Through xylem vessels; long, continuous columns that also. Provide structural support to stem
126
Explain cohesion-tension theory
Water molecules form HBs with each other, causing them to ‘stick’ together (cohesion).
The surface tension of water also creates this sticking effect.
Therefore as water is lost through transpiration, more can be drawn up stem.
127
What are 3 components of phloem vessels
Seive tube elements = form a tube to transport sucrose in dissolved form of sap
Companion cells = involved in ATP production for active loading of sucrose into sieve tubes
Plasmodesmata = gaps between cell walls where cytoplasm links, allowing substances to flow
128
Name process whereby organic materials are transported around plant
Translocation
129
How does sucrose in leaf mov into phloem
Sucrose enters companion cells of phloem vessels by active loading, which uses ATP and a diffusion gradient of H+.
Sucrose then diffuses from companion cells into sieve tube elements through plasmodesmata
130
How do phloem vessels transport sucrose around plant
As sucrose moves into tube elements, water potential inside phloem is reduced.
This causes water to enter via osmosis from xylem and increases hydrostatic pressure.
Water moves along sieve tube towards areas of lower hydrostatic pressure.
Sucrose diffuses into surrounding cells where it’s needed
131
Give evidence for mass flow hypothesis of translocation
Sap is released when stem is cut, therefore ther must be pressure in phloem
There’s a higher sucrose conc in leaves than roots
Increasing sucrose levels in leaves results in increased sucroses in phloem
132
Give evidence against mass flow hypothesis of translocation
Structure of sieve tubes seems to hinder mass flow
Not all solutes move at same speed, as they would in mass flow
Sucrose is delivered at same rate throughout plant, rather than to areas with lowest sucrose conc first.
133
How can ringing experiments be used to investigate transport in plants
Bark and phloem of tree are removed in ring, leaving behind xylem.
Eventually the tissues above missing ring swells due to accumulation of sucrose as tissue below begins to die.
Therefore sucrose must be transported in phloem
134
How can tracing experiments be used to investigate transport in plants
Plants are grown in presence of radioactive CO2, which will be incorporated into plants sugars.
Using autoradiography, we can see that areas exposed to radiation correspond to where the phloem is.
