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Biology yr 12 > Mass transport > Flashcards

Mass transport Flashcards

1
Q

Layout of Circulatory System?

A

 heart pumps blood which is carried in arteries which flow into arterioles which flow into capillaries which then are carried in venules then veins back to the heart
 Artery to Arterioles to Capillaries to Venules to Veins
 Artery/Arterioles carry blood away from the heart
(arterioles are small arteries)
 Capillaries are the site of exchange (nutrients out, waste in)
 Veins/Venules return blood back to the heart
(venules are small veins)

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2
Q

Heart?

A

 job is to pump blood around the body (delivers nutrients to cells and remove waste)
 made of 4 muscular chambers (2 atria, 2 ventricles)
 atria pumps blood to ventricles, ventricles pump blood out of heart (R to lungs, L to body)
 ventricles thicker then atria (has to pump blood further)
 left ventricle has a thicker muscular wall then right ventricle, therefore has stronger contractions, so can generate higher pressure and pump the blood further around the body

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3
Q

Blood vessels of the heart?

A

 artery takes blood away from the heart, vein returns blood to the heart
 Vena Cava supplies R atrium (with deoxygenated blood from body)
 Pulmonary Vein supplies L atrium (with oxygenated blood from lungs)
 R ventricle supplies Pulmonary Artery (deoxygenated blood to lungs)
 L ventricle supplies Aorta (oxygenated blood to body)

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4
Q

Job of valves in heart?

A

 Ensure one way flow of blood, no backflow
 (blood flows from atria to ventricles to arteries)
 2 sets of valves: Atrio-ventricular Valve & Semi-lunar Valve
 AV valve = between atria and ventricles
 SL valve = between ventricles and arteries

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5
Q

When are AV valves open or closed?

A

Open = pressure in atria greater then pressure in ventricles,
Closed = pressure in ventricles greater then pressure in atria

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6
Q

When are SL valves open or closed?

A

Open = pressure in ventricles greater then pressure in arteries
Closed = pressure in arteries greater then pressure in ventricles

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7
Q

Diastole process?

A
  • Blood enters the atria from the vena cava and the pulmonary vein
  • Increases atrial pressure opens the AV valves
  • Blood flows into ventricles
  • Walls of both atria and ventricles are relaxed
  • The ventricle relaxation reduces the pressure inside the ventricle
  • Pressure is lower in the ventricle than in the aorta and pulmonary artery
  • Semi-lunar valves close
  • The closing valves cause the ‘dub’ sound of the heart beat
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8
Q

Systole process?

A
  • The walls of the atria contract at the same time
  • Blood pushed into ventricles
  • Ventricle walls are relaxed to receive the blood
  • Pause to allow ventricles to fill
  • Increase in BP in ventricles closes the AV valves to prevent backflow into atria
  • Pressure rises which opens SL valves
  • Blood leaves through aorta and pulmonary artery
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9
Q

What causes the Heart Sounds?

A

 when the valves close
 1st = AV closes
 2nd = SL closes

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10
Q

Formula for Cardiac Output?

A

 CO = Stroke Volume x Heart Rate
 stroke volume = volume of blood pumped out of the heart in one beat
 heart rate = number of beats per minute
 Cardiac Output = volume of blood pumped out of the heart in one minute

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11
Q

Role of Arteries/Arterioles?

A

 generally carry oxygenated blood away from the heart
 for example, Coronary Artery to heart muscle
Hepatic Artery to liver
Renal Artery to kidneys
 exception = Pulmonary Artery carries deoxygenated blood to lungs

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12
Q

Role of Veins/Venules?

A

 generally carry deoxygenated blood back to the heart
 for example, Coronary Vein from heart muscle
Hepatic Vein from liver
Renal Vein from kidneys
 exception 1 = Pulmonary Vein carries oxygenated blood back to the heart
 exception 2 = Hepatic Portal Vein carries deoxygenated blood from digestive system to liver (for filtering)

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13
Q

Function of Arteries/Arterioles?

A

carry blood away from the heart so should be able to withstand high blood pressures & maintain high blood pressures

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14
Q

Structure of Arteries/Arterioles?

A

 narrow lumen = maintains pressure
 lining made of squamous epithelial cells = smooth lining to reduce friction
 thick wall = withstand pressure
 elastic tissue in wall,
ventricles contract – elastic tissue stretches to withstand pressure ventricles relax – elastic tissue recoils to maintain pressure and smooth out flow
 smooth muscle in wall (particularly in arterioles),
smooth muscle contracts – lumen narrows and arteriole constricts
smooth muscle relaxes – lumen widens and arteriole dilates
 collagen in wall
prevents artery from tearing

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15
Q

Function of Veins/Venules?

A

return blood back to the heart, the blood is under low pressure

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16
Q

Structure of Veins/Venules?

A

 wide lumen = ease of blood flow
 lining made of squamous epithelial cells = smooth lining to reduce friction
 thin wall = vein can be squashed by skeletal muscle pushing blood back to the heart
 valves in lumen = prevents backflow of blood

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17
Q

Function of Capillaries?

A

 site of exchange
 3 locations,
With Alveoli, takes in O2 and removes CO2
With Microvilli, takes in glucose/amino acids/monoglyceride and fatty acids/vitamins/minerals
With All Cells, deliver nutrients and remove waste

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18
Q

Adaptation of Capillaries?

A

 many small capillaries = large surface area
 thin wall, one cell thick, squamous epithelial cells = short diffusion distance
 pores between cells = allows fluid to move in and out
 narrow lumen = increase diffusion time and decrease diffusion distance

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19
Q

Content of Blood?

A

 main component = Plasma (fluid)
 plasma carries,
 Cells = red blood cells, white blood cells, platelets
 Solutes = nutrients, waste, protein

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20
Q

How does exchange occur between Capillaries & All Cells?

A

 by mass flow
 fluid moves out of the blood in the capillaries carrying the nutrients
 fluid moves back into blood in the capillaries carrying the waste
 (fluid in the blood called plasma, fluid surrounding cells called tissue fluid, fluid in lymph system called lymph)

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21
Q

How is tissue fluid formed and returned to circulatory system?

A

 at the start of the capillary (arterial end) there is a build up hydrostatic pressure
 this pushes fluid out of the capillary via the pores
 the fluid carries the nutrients with it
 the fluid surrounds the cells, this is called tissue fluid
 at the finish of the capillary (venous end) the fluid moves back in by osmosis
 the capillary has low water potential due to the presence of proteins (too large to move out of capillaries)
 any excess tissue fluid is picked up by the lymph system and deposited in the vena cava

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22
Q

Why does high blood pressure cause accumulation of tissue fluid?

A

increases hydrostatic pressure, so more tissue fluid is formed – not as much can be returned to the circulatory system

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23
Q

Why does high blood pressure cause accumulation of tissue fluid?

A

increases hydrostatic pressure, so more tissue fluid is formed – not as much can be returned to the circulatory system

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24
Q

Why does diet low in protein cause accumulation of tissue fluid?

A

the water potential in the capillary is not as low as normal, so not as much fluid can move back into the capillary by osmosis

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25
Q

Blood Pressure changes along the Circulatory System?

A

Arteries =
- highest pressure (connects directly with heart/ventricles)
- pressure fluctuates (increases when ventricles contract which causes the elastic tissue to stretch, decreases when ventricles relax which causes the elastic tissue to recoil)
- overall decrease in pressure due to friction

Arterioles =
large decrease in pressure due to increase in total cross-sectional area (ensures pressure is not to high to damage capillaries)

Capillaries =
pressure here is called hydrostatic pressure (decreases due to a loss in fluid)

Venules/Veins =
blood under low pressure

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26
Q

Job of Red Blood Cells?

A

 found in humans/mammals (animals)
 carries haemoglobin
 haemoglobin carries oxygen

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27
Q

Structure of Haemoglobin?

A

 globular protein (soluble & specific 3d shape)
 quaternary structure made of 4 polypeptide chains (2α, 2β)
 each chain carries a haem group
 each haem group carries Fe2+
 each Fe2+ carries an O2
 therefore, each haemoglobin carries 4 lots of O2

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28
Q

Job of Haemoglobin?

A

load oxygen in the lungs and deliver it to the respiring tissues

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29
Q

What is Affinity?

A

the level of attraction haemoglobin has to oxygen
(high affinity = strong attraction, low affinity = weak attraction)

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30
Q

Role of haemoglobin in oxygen transport?

A

 haemoglobin has High Affinity in the lungs – due to high partial pressure of oxygen and low partial pressure of carbon dioxide, so haemoglobin loads/associates oxygen in the lungs and becomes saturated (full)
 the haemoglobin is transported in the blood in the red blood cell
 at the respiring tissues, haemoglobin has Low Affinity – due to low partial pressure of oxygen and high partial pressure of carbon dioxide, so oxygen is unloaded/dissociated/delivered and haemoglobin becomes unsaturated

31
Q

Relationship between O2 Partial Pressure & Affinity/Saturation of Haemoglobin?

A

 positive correlation
 as O2 partial pressure increases, affinity/saturation of haemoglobin increases
 the correlation is not linear but is curved (produces a s-shaped, sigmoid curve called Oxygen Dissociation Curve)
 middle portion of ODC has a steep gradient so when respiring tissues change from resting to active and partial pressure of O2 falls, there is a large drop in affinity, so more O2 would be delivered to the respiring tissues

32
Q

Relationship between CO2 Partial Pressure & Affinity/Saturation of Haemoglobin?

A

 negative correlation
 as CO2 partial pressure increases, affinity/saturation of haemoglobin decreases
 this occurs at the site of respiring tissues = the carbon dioxide lowers the pH of the blood, makes the haemoglobin change shape, so oxygen is released, lowering affinity. this shifts the ODC to the right, called the bohr shift. benefit = more oxygen delivered to respiring cells

33
Q

How does a Fetus receive oxygen?

A

from mother’s blood, oxygen dissociates from mother’s haemoglobin and associates with fetal haemoglobin in the placenta – fetal haemoglobin has a higher affinity compared to mother’s haemoglobin

34
Q

Benefit of fetal haemoglobin having high affinity?

A

fetal haemoglobin’s ODC will be to the left, it has high affinity – so the oxygen will dissociate from the mother’s haemoglobin and associate with the fetal haemoglobin at the low partial pressures of oxygen in the placenta, so it has enough oxygen for its needs

35
Q

Why do adults not keep with fetal haemoglobin?

A

the high affinity will mean less oxygen will be unloaded at the respiring tissues

36
Q

Affinity of Organisms in a Low Oxygen Environment?

A

has a high affinity, curve to the left, therefore it can readily associate oxygen at the low oxygen partial pressures

37
Q

Affinity of Active Organisms?

A

has a low affinity, curve to the right, therefore more oxygen can be unloaded to meet the cell’s demand for more respiration

38
Q

Affinity of Small Organisms?

A

have a large surface area to volume ratio, lose a lot of heat, needs to respire to generate heat, therefore has a low affinity, curve to the right, so unloads enough oxygen for the cells demand of more respiration

39
Q

What are the Exchange & Transport Systems in Plants?

A

 exchange systems = leaf and root
 leaf to absorb light and CO2 for photosynthesis
 roots to absorb water and minerals
 transport systems = xylem and phloem
 xylem transports water and minerals
 phloem transports glucose/sugars
 xylem transports in one direction from roots to leaves, phloem transports in both directions

40
Q

What are the Exchange & Transport Systems in Plants?

A

 exchange systems = leaf and root
 leaf to absorb light and CO2 for photosynthesis
 roots to absorb water and minerals
 transport systems = xylem and phloem
 xylem transports water and minerals
 phloem transports glucose/sugars
 xylem transports in one direction from roots to leaves, phloem transports in both directions

41
Q

Job of the Roots?

A

 absorb water and minerals
 absorbs water by osmosis
 absorbs minerals by active transport
 plants need water for photosynthesis, cytoplasm hydration, turgidity of cells
 plants need magnesium, nitrate, phosphate (magnesium to make chlorophyll, nitrate to make amino acids, phosphate to make phospholipids/ATP/DNA)

42
Q

Function of the Xylem?

A

transport water and minerals from roots, up the plant, to the leaves

43
Q

Structure of the xylem?

A

 long continuous hollow tube (no resistance to water flow)
 narrow lumen
 wall made out of lignin
 lignin: strong, waterproof, adhesive
 wall contains pits/pores (water and minerals can leave)

44
Q

How does water move up the xylem?

A

 loss of water at the leaves (transpiration)
 water moves from the top of the xylem into the leaf by osmosis (transpirational pull)
 this applies TENSION to the column of water in the xylem
 the column of water moves up as one as the water particles stick together, COHESION
 this is is the cohesion-tension theory
 it is supported by capillary action, adhesion and root pressure
 (capillary action = water automatically moves up narrow lumen of xylem)
 (adhesion = water particles stick to lignin in wall of xylem)
 (root pressure = water absorbed at the roots pushes the column of water up slightly by hydrostatic pressure)

45
Q

Why does the diameter of a tree decrease during the day?

A

 more light and higher temperature
 increase rate of transpiration
 increase transpirational pull
 water pulled up xylem by cohesion-tension
 because the water particles stick to the wall of the xylem (adhesion)
 the walls of the xylem are pulled inwards

46
Q

Structure of Leaves?

A

 upper layer called Upper Epidermis
 waxy cuticle on upper epidermis (barrier to reduce water loss)
 beneath the upper epidermis are Palisade Cells
 palisade cells are were photosynthesis takes places
 beneath palisade cells are Spongy Mesophyll Cells
 are loosely packed leaving air spaces to allow ease of gas exchange
 lower layer called Lower Epidermis

47
Q

Structure of Leaves?

A

 upper layer called Upper Epidermis
 waxy cuticle on upper epidermis (barrier to reduce water loss)
 beneath the upper epidermis are Palisade Cells
 palisade cells are were photosynthesis takes places
 beneath palisade cells are Spongy Mesophyll Cells
 are loosely packed leaving air spaces to allow ease of gas exchange
 lower layer called Lower Epidermis

48
Q

Adaptation of palisade cells for photosynthesis

A

 located near top of leaf, closer to light
 large size, large surface area for light
 thin cell wall, short diffusion distance for carbon dioxide
 contains many chloroplasts, site of photosynthesis
 large vacuole, pushes chloroplast to the edge of the cell closer to light

49
Q

Structure of chloroplast?

A

 organelle for photosynthesis
 has double membrane
 contains discs called thylakoids
 thylakoids contain chlorophyll
 stack of thylakoids called granum
 thylakoids surrounded by a fluid called stroma

50
Q

How does Exchange occur in Leaves?

A

 lower epidermis of leaf contains pairs of cells called Guard Cells
 when turgid, guard cells form an opening called Stomata
 gas exchange occurs via the stomata
 In Day, plant photosynthesises and respires, CO2 moves in for photosysnthesis and O2 moves out (some is used in respiration)
 At Night, plant only respires, O2 moves in for respiration and CO2 moves out

51
Q

What is Transpiration?

A

loss of water vapour from the leaf via the stomata

52
Q

How does Transpiration occur?

A

 moist lining of spongy mesophyll cells evaporate forming water vapour
 water vapour builds up in air spaces
 if water vapour concentration is high enough & stomata is open, water vapour diffuses out

53
Q

Factors that increase rate of transpiration?

A

 light = more light, more stomata open, increase surface area for transpiration
 temperature = more temperature, more evaporation (increase water vapour concentration) & more kinetic energy
 wind = more wind, maintains concentration gradient
 humidity = less humidity, less water vapour in the surrounding air, increase in water vapour concentration gradient

54
Q

Principle of potometer?

A

 as transpiration occurs from the leaves, the plant will pull up more water from the potometer by cohesion-tension causing the bubble to move towards the plant
 the more water lost by transpiration, the more water taken up, the further the bubble moves

55
Q

how to calculate Rate of Transpiration?

A

 rate of transpiration = volume of transpiration divided by time
 for volume of transpiration, distance bubble moved x cross-sectional area of tube (πr2)

56
Q

How to set up a potometer?

A

 choose healthy leaf and shoot
 cut shoot underwater and connect to potometer underwater (prevents air bubbles entering/blocking xylem)
 ensure potometer is air tight and water tight

57
Q

What does a potometer actually measure?

A

measures rate of water uptake as a result of water loss from plant
(water loss can be due to: transpiration, photosynthesis, making cells turgid, loss from potometer)

58
Q

What is a Xerophyte?

A

a plant adapted to reduce water loss (reduce transpiration)

59
Q

Adaptations of Xerophyte?

A

 spiky, needle like leaves = reduced surface area
 thick waxy cuticle = waterproof, impermeable barrier
 densely packed spongy mesophyll = less air spaces, less water vapour build up
 sunken stomata/hairy leaves/rolled up leaves = traps moist layer of air,
reduces concentration gradient

60
Q

Function of Phloem?

A

transport organic material (e.g. Sucrose) up and down a plant

61
Q

Structure of phloem?

A

made of 2 parts (Sieve Tube with Companion Cells alongside)

62
Q

How does phloem transport organic material like sucrose?

A

 by principle of Mass Flow (mass flow of water carries the sucrose)
 Sucrose loaded into Phloem at Source (leaves)
 Hydrogen Ions (H+) actively transported from companion cells into source
 therefore, H+ diffuses back into companion cells from source
 as they do, they pull in sucrose with them by co-transport
 sucrose then diffuses into sieve tube
 this lowers the water potential of sieve tube so water follows by osmosis
 this water will carry the sucrose by hydrostatic pressure (mass flow)
 Sucrose unloaded from Phloem at Sink (roots)
 sucrose moves out of phloem/sieve tube into sink by diffusion
 water follows by osmosis

63
Q

describe ventricular pressure changes?

A
  • starts low
  • increases as blood enters from atria
  • AV valve closes
  • pressure is higher than in the aorta
  • blood is then forced through SL valves
  • large pressure increase when ventricular walls contract
  • pressure falls when ventricles relax
64
Q

describe ventricular volume changes?

A
  • increases when atria contract to fill ventricles
  • decreases when blood is forced out through the SL valves
  • volume increases again when ventricles fill with blood
65
Q

describe aortic pressure changes?

A
  • increases when blood leaves ventricles
  • elastic walls recoil to cause a rise in pressure before the relaxation phase
66
Q

describe atrial pressure changes?

A
  • pressure is always low due to thin walls
  • peaks when atria contract
  • drops when AV valves close and the walls relax
  • gradual increase in pressure caused by atria filling
  • pressure drops when AV valves open and blood moves into the ventricles
67
Q

What is a potometer?

A
  • A potometer can be used to investigate the effect of environmental factors on the rate of transpiration
  • measures the rate of water uptake
68
Q

Evidence supporting the mass flow hypothesis?

A
  • there is a pressure within sieve tubes, as shown by sap being released when they are cut.
  • the concentration of sucrose is higher in leaves (source) than in roots (sink).
  • downward flow in the phloem occurs in daylight, but ceases when leaves are shaded, or at night.
  • increases in sucrose levels in the leaf are followed by similar increases in sucrose levels in the phloem a little later.
  • metabolic poisons and/or lack of oxygen inhibit translocation of sucrose in the phloem.
  • companion cells possess many mitochondria and readily produce ATP.
69
Q

Evidence questioning the mass flow hypothesis

A
  • the function of the sieve plates is unclear, as they would seem to hinder mass flow (it has been suggested that they may have a structural function, helping to prevent the tubes from bursting under pressure).
  • not all solutes move at the same speed - they should do so if movement is by mass flow.
  • sucrose is delivered at more or less the same rate to all regions, rather than going more quickly to the ones with the lowest sucrose concentration, which the mass flow theory would suggest
70
Q

Describe the process of ringing experiments

A
  • cut a section of the outer layer, to remove the circumference of the woody stem, ensuring the inner layer is still attached to the rest of the plant
  • the region above the missing ring of tissue will swell
  • this liquid will be full of sugars and other dissolved organic substances
  • non-photosynthetic tissues in the region below the ring will wither and die, while those above the ring will continue to grow
71
Q

results of ringing experiments?

A

shows that the phloem is responsible for translocating sugars in plants

72
Q

describe the process of tracer experiments

A
  • 14C makes radioactively labelled carbon dioxide (14CO2)
  • plant will be grown in a atmosphere containing 14CO2
  • the isotope will be incorporated in the sugars that are produced during photosynthesis
  • the radioactive sugars can be traced as they move within the plant using x-ray film to detect where the isotope is within the plant
  • the blackened regions on the x-ray film correspond with where the phloem tissues are on the stem
  • the other tissues do not blacken the film, meaning they do not carry the sugars, so only the phloem is responsible for translocation
73
Q

what is the bohr effect?

A
  • Changes in the oxygen dissociation curve as a result of carbon dioxide levels
  • When the partial pressure of carbon dioxide in the blood is high, haemoglobin’s affinity for oxygen is reduced

Biology yr 12 (8 decks)

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