chapter 7 - mass transport Flashcards
(66 cards)
1
Q
What is the structure of the haemoglobin protein ?
A
- quaternary structure
- each folded into a 3D folded shape
- 4 chains, each have a haem group in them
- this haem group has iron and this is where the oxygen binds to
- also is a globular protein
- and had hydrophilic groups on the outside so is soluble in water
2
Q
Are there proteins similar to haemoglobin ?
A
- yes, haemoglobin is part of a group of chemically similar molecules
- found in different organisms and different tissue of the same organism
- and the different types of haemoglobin affect its ability to attract oxygen
- e.g myoglobin
3
Q
What does affinity of haemoglobin mean ?
A
- its ability to attract ( bind ) to oxygen
4
Q
What does saturation of haemoglobin mean ?
A
- when haemoglobin is holding the maximum amount of oxygen it can bind
- of how much oxygen the haemoglobin has
5
Q
What is the loading / association of haemoglobin ?
A
- when oxygen is binding to haemoglobin
6
Q
What is the unloading / dissociation of haemoglobin ?
A
- when oxygen detaches ( unbinds ) from haemoglobin
7
Q
What does an oxygen dissociation curve show ?
A
- at high partial pressures, haemoglobin is almost fully saturated with oxygen
- at low partial pressures, oxygen is unloaded from the haemoglobin
- the graph flattens out at the top because it becomes harder to load the 4th oxygen
- because there is only one chain left
8
Q
What does the oxygen dissociation curve show about the affinity of haemoglobin ?
A
- at lower partial pressures, haemoglobin’s affinity for oxygen is lower
- lower partial the will be at the respiring tissue meaning its easier for haemoglobin to unload the oxygen so it can be used by the respiring tissue
- at higher partial pressures, haemoglobin has a higher affinity for oxygen
- high partial pressures is at the lungs
- so it will be easy for the haemoglobin to bind to the oxygen there
9
Q
What is the cooperative binding of haemoglobin ?
A
- its hard for the first oxygen to bind to the haemoglobin
- but once it does it changes shape
- which makes it easier for the next oxygen to bind
- which is why the curve get steep
10
Q
What is the Bohr affect ?
A
-when high carbon dioxide concentration causes the oxyhemoglobin curve to shift to the right
- carbon dioxide will dissolve to form carbonic acid at respiring tissues so the pH decreases
- this causes the shape of the protein to change and at this stage the curve will shift to the right, there is a decreases affinity and more oxygen is unloaded
- at low CO2 concentrations, the curve shift to the left and there is an increased affinity and so more oxygen is loaded
- this happen in the alveoli
11
Q
How does haemoglobin differ in differ to animals ?
A
- animals will have different types of haemoglobin an these will have different affinities for oxygen
- and this is an adaptation to their environment
12
Q
How dos foetal haemoglobin differ to adult haemoglobin
A
- foetal haemoglobin has a higher affinity for oxygen as the same partial pressures
- as its only source of oxygen is from the mothers haemoglobin so it needs to be able to grab it ( foetus’s cannot inhale or exhale )
13
Q
How does llama haemoglobin differ from human haemoglobin ?
A
- llamas live at high altitudes where there is a low partial pressures
- llama’s haemoglobin has a higher affinty for oxygen
- so even in low partial pressures the llama can still get its oxygen
14
Q
How does dove haemoglobin differ from human haemoglobin
A
- a dove’s haemoglobin has a lower affinity for oxygen
- as doves have a higher metabolic rate than human
- as there’s lots of muscle contraction when they fly
- so more unloading
15
Q
How does earthworm haemoglobin differ from human haemoglobin ?
A
- earthworm haemoglobin has a higher affinity
- as there is lower partial pressures under the ground
- so more loading
16
Q
What is the circulatory system like in mammals ?
A
- its closed = the blood remains within vessels
- and its double circulatory = blood passes through the heart twice in each circuit, one circuit take blood to lungs and the other to the rest of the body
17
Q
Why do mammals have a double circulatory system ?
A
- to manage the pressure of blood flow
- at lungs, blood is at a lower pressure which prevents damage to the capillaries in alveoli and reduces the speed of the blood flow, so time for gas exchange
- the oxygenated blood then pumped out of the heart at higher pressure to the rest of the body so that blood can reach all of the respiring tissues
18
Q
What are the key blood vessels ?
A
- vena cava ( heart )
- aorta ( heart )
- pulmonary artery ( heart + lungs
- pulmonary vein ( heart + lungs )
- renal artery ( kidney )
- renal vein ( kidney )
- these key blood vessels are connected by arteries , arterioles, capillaries and veins
19
Q
What are the 2 divisions of the mammalian circulatory system ?
A
- systematic circulatory system and the pulmonary circulatory system
20
Q
A
21
Q
How does the systematic circulatory system work ?
A
- oxygenated blood is pumped out of the heart by the aorta to most body tissues
- other blood vessels, like renal artery , branch from the aorta to deliver blood to other body tissues
- vein collect deoxygenated blood from these organs ( renal vein collects deoxygenated blood from kidneys )
- deoxygenated blood is returned to the heart by the vena cava
22
Q
How does the pulmonary circulatory system work ?
A
- deoxygenated blood is pumped out of the heart by the pulmonary artery to the lungs
- oxygenated blood is returned to the heart by the pulmonary vein from the lungs
23
Q
Describe the structure of arteries ?
A
- they have collagen to prevent them from bursting and maintains their shape
- the have an elastic layer with elastin to maintain blood pressure by being able to stretch and recoil
- they have a thick smooth muscle layer which contracts/ relaxes to constrict /dilate the lumen which controls the blood flow
24
Q
Describe the structure of arterioles ?
A
- thicker muscle layer than arteries so there’s more contraction so more constriction blood flow is restricted into the capillaries
- thinner elastic layer than arteries as blood pressure is lower
25
What is vasoconstriction and vasodilation ?
- vasoconstriction = smooth muscle contracts, blood vessel is constricted so blood flow is decreased
- vasodilation = smooth muscle relaxes, blood vessel dilates so blood flow is increased
26
Describe the structure of the veins
- collagen to prevent vessel form bursting and maintains vessel shape
- thinner layer of smooth muscle so cannot contr flow of blood
- thinner elastic layer as blood is at a lower pressure so they wont burst
- thinner wall as pressure is low to be a risk and it allows the veins to be flattened which aids the flow of blood in them
- they have valves to prevent the back flow of blood because the pressure is low
- when the body muscles contract veins are compresses which increases the blood pressure, the valves ensure the pressure is directed in one direction
27
Describe the structure of capillaries
- they have a epithelial layer which is thin to provide a short diffusion systems
- very narrow lumen which allows body cells to be close to red blood cells and slows blood flow which allows time fro diffusion
- they ae highly branches to allow large surface area for diffusion
- there is no muscle or elastic layer
28
What muscle is the heart made of ?
- cardiac muscle
- is a thick muscular layer
- its myogenic meaning it can contract and relax without nervous or hormonal system
- and it never fatigues as long as it has enough oxygen
29
What are coronary arteries ?
- vessel that surround the heart ans they breach of the aorta
- they supply cardia muscle with oxygenated blood
- heart attacks are caused by blockages in the coronary arteries
30
What are the 4 chambers of the heart ?
- left atrium
- right atrium
- both atriums collect blood from veins
- left ventricle
- right ventricle
- pump blood into arteries to the rest for the body
31
What are some features of the chambers of the heart ?
- the atria have thinner muscular walls than the ventricles because thy only have to pump blood to ventricles whilst ventricle haveto pump blood to other parts of the body
- the atria also have elastic walls to stretch when blood enters
- and the right ventricle wall is thinner than the left ventricle
- because its only pumping to a short distance to the lungs and lower pressure will not damage lungs and allow more time for diffusion
- the left ventricle is thicker because it has to pump blood to a greater distance to the rest of the body
32
Describe the blood vessels in the heart
- vena cava carries deoxygenate blood from the body into heart through the right atrium
- pulmonary vein carries oxgyented blood from lungs into heart thourgh left atrium
- pulmonary artery carries deoxgyenated blood from heart to lungs through right ventricle
- aorta carries oxygneatd blood from heart to the rest of the body through let atrium
33
Describe the valves in the heart
- semi lunar valves , between ventricles and aorta and pulmonary artery , they prevent back flow into ventricles when they relax
- atrioventricular valves which are between ventricles and arteries
- they open when there is a higher pressure behind them and close when there is a higher pressure in front of
- so the blood only flows in ones direction
34
What is the septum ?
- cardiac muscles which seperated oxygenated blood from deoxygenated blood
- this is importance so a high oxygen concentration is maintained in the blood so there is a diffusion gradient at respiring blood cells
35
What are the 3 stages of the cardiac cycle ?
- atrial systole
- ventricular systole
- diastole
36
What happens during the arterial systole ?
- blood enters the head through the veins
- as blood enters the atria, the atria contract which causes he volume to decrease and the pressure to increase
- the pressure in the atria is now higher than that in the ventricles so the atrioventricular valves open
- blood now flow into the ventricles
37
What happens during the ventricular systole ?
- as blood flows into the ventricles the ventricles contracts
- this causes the volume to decrease and the pressure to increase
- the pressure into the ventricles exceed that of the atria so the atrioventricular valves close
- the pressure into the ventricles are higher that that in the arteries so the semilunar valves open
- no blood is pushed into the aorta and pulmonary artery
38
What happens during diastole
- as blood flows into tha aorta and pulmonary artery, the ventricles relax
- this causes the pressure in the ventricles to fall below that of the ones in the arteries so the semilunar valves open close
- now the volume and pressure begin to increase again as blood fill the heart via the veins again
39
What is the formula for cardiac output ?
- cardiac output = heart rate ( in beats/minute ) x stroke volume (ml/beat)
40
What is tissue fluid ?
- a fluid containing water, glucose, amino acids, fatty acids, ions and oxygen
41
How is tissue fluid formed ?
- arterioles connect to capillaries
- at the arteriole end, high pressure blood is flowing through the
- meaning fluid is forced out and surrounds the cells
- this is called ultrafiltration
- meanwhile out the lower end of the cells, there is a lower hydrostatic pressure and a lower water potential in the capillaries
- so the fluid moves back in via osmosis/ osmotic pressure
42
What is and isn’t forced out of the capillaries ?
- forced out: water molecules,dissolved minerals and salts, glucoses, small proteins and amino acids, fatty acids, oxygen
- kept in: red blood cells, platelets and large proteins
- the stuff forced out can go out because they’re small enough
43
What do the lymph vessels do ?
- any fluid that isn’t reabsorbed, because equilibrium has been reaches or osmotic pressure isn’t high enough, enter the lymph vessels
- these go the lymph nodes and the fluid is eventually drained back into the bloodstream near the heart
44
What is tidal volume ?
- volume of air Thant enters and leaves the lungs at rest
45
What is the vital capacity ?
- the maximum volume of air you can inhale or exhale
46
What is residual volume ?
- volume air left in lungs after strongest inhalation
47
What is the total lung capacity ?
- vital capacity + residual capacity
48
What is pulmonary ventilation and how do you work it out ?
- total volume of air that is moved into the lungs during one minute
- pulmonary ventilation (dm/min)= tidal volume (dm3) x ventilation rate ( per minute )
49
Why would bronchitis ad asthma reduce gas exchange ?
- there is a small lumen of the bronchi
- so less air entering and leaving alveoli
- which means smaller concentration gradient
50
How does emphysema and pulmonary fibrosis reduce gas exchange
- alveoli are damaged
- lower surface area for gas exchange
- in pulmonary fibrosis the wall of the alveoli are too thick
51
What is the structure of xylem tissue ?
- elongated hollow tubes without end walls
- they have no organelles
- they have lignin to provide strength in the walls
- they have non-ignified areas of the wall to allow water and ions to move in and out of the tissue
52
What is transpiration ?
- the loss of water vapour from the stomata
- this happens in the leaves
53
What factors affect transpiration rate ?
- light intensity = more light means more stomata open which means large surface area for evaporation
- temperature = higher temperature means more kinetic energy so molecules morev faster which increases transpiration rate
- humidity = more humidity increases water potential outside leaf do water potential gradient is decreases and less water will evaporate out
- wind = wind will move umid air away from leaf which will decrease water potential outside leaf which increases water potential gradient so more wtaer will evaporate out
54
How does water get from the soil to the leaves
- water moves in by osmosis from soil into root hair cells, root hair cells have large surface area area and there is a high water potential gradient
- water moves through the cortex by either the apoplasti ( cell wall pathways ) which relies on cohesion ad wtaer moving through gaps in cellulose or the symplastic ( cell membrane pathway ) which relies on osmosis through plasmodesmata
- water is then able to move up through the xylem
55
How is water able to move directly up the xylem
- due to the cohesion tension Theory which includes cohesion of water, adhesion / capillarity and root pressure
56
What is root pressure ?
- because water is entering the root hair cels there is an increased hydrostatic pressure at the root end of the xylem
- this pushes the waster above it
- this is positive pressure
57
What is the cohesion tension theory ?
- water can move directly upwards against gravity be sure water molecules are dipolar and so can form hydrogen bonds between molecules which cause them to stick together in a continius column
- water can also adhere to the walls of the xylem which helps pull the wtaer upwards
- capillarity is when the adhesion makes the walls of the xylem to be pulled in so they use becomes narrower
- and as water leaves the leaves by transpiration, there is negative pressure
- which pulls the water up
58
What evidence is there for cohesion tension theory ?
- tree diameters are narrower during the day as there’s more transpiration going on meaning more adhesion
- water does not leak out when you break the stem
59
What does a potometer do ?
- measure the rate of uptake of water from a plant
60
How do we use a potometer
- a sample of a plant if cut underwater to prevent any air from entering the xylem and breaking the continuous column of water
- potometer if filled with water to make sure all air bubbles are removed
- the cut left plant is attached to the potometer using rubber seals and petroleum jelly because pretoleum jelly is water proof and will make sure no water leaves and no air enter
- one air bubble is purposely introduced into the potometer and the distance this air bubbles moves in a certain amount of time is recorded
61
How do work out the transpiration rate
- the volume of water taken out / time
- to work out volume must know how to do volume of cylinder
- work out cross section area then times by the length which is the length that the air bubbles moves moved
62
What variable would we have to control if we used a potometer on two different plant species
- leaf surface area
63
What is the structure of the phloem ?
- sieve tubes hwhci ae living cells with no nucleus, little organelles, hollow with perforated end walls
- companion cells which have lots of mitochondria for atp
64
What is the mass flow hypothesis ?
- mass flow happens from source of production which is the leaves to the sink which is the site where organic substances are used
65
How does translocation work
- photosynthesis is happening in the source cells
- sucrose is then actively transported into the sieve cells from the source cells using the companion cells
- this is when h+ ions are actively transported into source cells from companion cells and then is co-transported into companion cells from source cells and then can move from facilitated diffusion into the sieve tube
- the movement of sucrose into this section of the sieve tube element lowers the water potential
- so water moves from the xylem into the sieve tube element by osmosis
- so now there’s a high hydrostatic pressure at his section of the sieve tube so it forces the water and solutes down into an area of low hydrostatic pressure
- now sucrose will move into the sink cell by active transport or facilitated diffusion and now the water potential is higher in this area
- so now water will move by osmosis back into the xylem
- sin cells include roots, seeds and fruits
66
What can we use to test for the mass flow hypothesis ( translocation )?
- tracing = radioactively labels carbon and giving the plant radioactively labelled carbon dioxide so that when it photsynthesises all the sugars produces will be radioactive labelled
- then slices from the stem can be placed on an x-ray and the section of the stem containing the sugars will turn black showing that it’s being transported by the phloem
-ringing = a ring of bark and phloem is removed from the tree trunk and the funk above the tree will swell and if you analyse this liquid it ill contain sugar, showing that the phloem is there and the sucrose liquid cannot move down because the phloem has been cut
