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Biology Paper 1 > 7: Mass transport > Flashcards

7: Mass transport Flashcards

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1
Q

Haemoglobin

A
  • quaternary structured protein
  • haemoglobin and red blood cells transport oxygen
  • each of the 4 polypeptide chain is associated with a haem group
  • this haem group each contains a ferrous ion which binds to an oxygen molecule. therefore each haemoglobin molecule can carry four oxygen molecules
  • biconcave structure (large sa)
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2
Q

to be efficient with transporting oxygen, haemoglobin must;

A
  • readily associate with oxygen at the surface where gas exchange takes place
  • readily dissociate with oxygen at tissues requiring it
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3
Q

How does haemoglobin change its affinity for oxygen under different conditions

A
  • the shape changes in the presence of certain substances
  • in the presence of carbon dioxide, the shape of hb binds more loosely to oxygen so it releases
  • respiring tissues = low conc oxygen, high conc co2, so low affinity for oxygen and dissociates
  • gas exchange surfaces = high conc of oxygen, low conc of co2, so high affinity for oxygen and associates
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4
Q

Oxygen dissociation curve

A
  • shape of hb makes it hard for first oxygen molecule to bind as closely packed together, so at low oxygen concs little oxygen binds
  • first binding changes quaternary structure shape which induces other subunits to bind as is easier which is positive cooperativity
  • but by the fourth molecule, it is harder to bind due to probability, less likely to find empty site
  • there is low affinity to left
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5
Q

the bohr effect

A
  • lots of carbon dioxide - high carbon dioxide partial pressure
  • oxyhaemoglobin curve shifts to the right
  • affinity decrease, so more readily unloads oxygen
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6
Q

loading and unloading of oxygen from hameoglobin

A
  • gas exchange surfaces co2 is removed so low concentrations
  • this raises pH, which changes the shape of the hameglobin to load oxygen more readily
  • when co2 conc high its acid so lowers the pH which causes the haemoglobin to change shape to have low affinity
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7
Q

fetal haemoglobin

A
  • curve shifts to the left
  • with the same partial pressure there is higher affinity
  • the fetus cant inhale or exhale, has to take oxygen from adults haemoglobin
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8
Q

llamas, doves and earthworms haemoglobin

A
  • llamas live in high altitudes so have a higher affinity for oxygen at lower partial pressures (moves left)
  • doves have a fast metabolism so need more oxygen for respiration so lower affinity (unloads more oxygen)
  • worm live underground so require haemoglobin with a high affinity (moves left)
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9
Q

does a mouse or an elephant have a high surface area to volume ratio

A
  • an elephant has a lower surface area to volume, which is why mammals need circulatory system (and they r active)
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10
Q

mammalian circulatory systems

A
  • closed (blood remains in vessels)
  • double circulatory system (the blood passes through the heart twice, 1 to lungs, 2 rest of body)
  • its double bc different parts of the body require different pressures. the lungs need a low pressure of blood, the ody needsa high pressure
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11
Q

blood vessels

A
  • heart (vena cava, aorta, pulmonarey artery, pulmonary vein)
  • lungs (pulmonary artery, pulmonary vein)
  • kidneys (renal artery, renal vein)
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12
Q

structure of the heart

A
  • left = oxygenated blood from lungs, pumps to body so thick muscular walls
  • right = deoxygenated blood from body, pumps blood to lungs so thin walled
  • the atrium is thin walled and elastic so stretches when collects blood
  • the ventricle is thick muscular walled as it contracts

both sides of heart pump at same time
- left and right atrioventricular valves to to prevent backflow of blood into atria when ventricule contracts

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13
Q

what are vessels called that connect the heart to the lungs

A

pulmonary vessels

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14
Q

properties of the cardiac muscle

A
  • myogenic (can contract and relax without input from nervous system or hormones)
  • never fatigues (aslong as supply of oxygen)
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15
Q

2 veins into the heart

A
  • vena cava (brings deoxygenated blood from the body back into the right atrium)
  • pulmonary vein (oxygenated blood from the lungs into the left atrium)
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16
Q

2 arteries away from the heart

A
  • aorta (carries oxygenated blood from the left ventrical to the body)
  • pulmonary artery (carries deoxygenated blood from the right ventricle to the lungs)
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17
Q

where are semi lunar valves found

A
  • in aorta and pulmonary artery
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18
Q

where are atroventricular valves found

A
  • between atrium and ventricles. two types;
  • bicuspid (two flaps)
  • tricuspid (three flaps)
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19
Q

how do valves work

A
  • prevent backflow by closing when there is high pressure infront of the valve
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20
Q

Septum

A
  • cardiac muscle down the middle and seperates left and right side of heart
  • so oxygenated blood isnt being diluted by deoxygenated side
21
Q

Myocardial infarction

A
  • blockage in arteries (blood clot) makes heart muscle deprived of oxygen
22
Q

Risk factors associated with cardiovascular diease

A
  • smoking (nicotine increases adrenaline which increases heart rate and blood pressure)
  • high blood pressure (stress, diet, exercise)
  • blood cholesterol (high and low density lipoproteins)
  • diet
23
Q

Cardiac cycle

A
  • diastole
    -atrial systole
  • ventricular systole
24
Q

Diastole

A
  • atria and ventricular muscles are relaxed
  • blood enters atrium by vena cava and pulmonary vein
  • the blood flowing into the atria increases the pressure
25
Q

Atrial systole

A
  • atria muscular walls contract, so volume decreases and increasing the pressure further
  • this causes atrioventricular valves to open and blood flows into the ventricules (ventricular diastole)
26
Q

Ventricular systole

A

after short delay
- ventricular walls contract, increasing pressure beyond that of the atria and causes the atrioventricular valves to shut
- semi lunar valves open
- blood pushes out ventricles into the arteries
-

27
Q

Cardiac output

A

= heart rate x stroke volume (volume of blood leaves heart each beat)

28
Q

Types of blood vessels

A
  • arteries (blood away from heart into arterioles)
  • arterioles (to capillaries)
  • capillaries (link arterioles to veins)
  • veins (carry blood from capillaries back to heart)
29
Q

the layers of blood vessels

A
  • fibrous outerlayer
  • muscle layer
  • elastic layer
  • thin inner lining
  • lumen
30
Q

Artery structure related to function

A
  • thick muscle layer compared to veins (so constriction and dilation can occur)
  • thick elastic layer compared to veins (to help maintain blood pressure)
  • thicker walls to help prevent walls from bursting
  • no valves
31
Q

Vein structure in relation to function

A
  • Thinner muscular layer so it cant control flow of blood
  • Thinner elastic layer as the pressure is lower
  • Wall thickness is thinner as pressures lower so low risk of bursting
  • Valves
32
Q

Capillaries

A
  • one cell thick
  • red blood cells just fit through diameter of the lumen so blood flow slows down so theres more time for diffusion
    -no muscle or elastic layer or valves
33
Q

Arterioles

A
  • muscle layers thicker than arteries to help restrict blood flow into capillaries
  • elastic layers and wall thickness thinner than arteries as lower pressure
  • no valves
34
Q

Tissue fluid

A
  • bathes the tissues
  • watery substance that contains glucose, amino acids, fatty acids, ions in solution and oxygen that supplies these to tissues by bathing them
35
Q

Formation of tissue fluid

A
  • blood pumped by heart passes through arteries, arterioles, capillaries, each smaller so creates high hydrostatic pressure.
  • this hydrostatic pressure causes ultrafiltration and the tissue fluid to move out of the blood plasma at the arterial end of capillaries
  • red blood cells, proteins and platelets are too large to cross the membranes
36
Q

return of tissues fluid back to the circulatory system

A
  • the loss of tissue fluid in capillaries lowers the hydrostatic pressure in them
  • by the time the blood has reached the venous end of the capillary network, the hydrostatic pressure is lower than off the tissue fluid outsdie it
  • therefore tissue fluid is forced back in by high hydrostatic pressure outside
  • also the plasma has lost water but still has large proteins so has a lower water potential than the tissue fluid so tissue loses water by osmosis
  • eventually with water moving back into capillaries equilbirium will be reached
  • the rest of the tissue fluid is absorbed by the lymphatic system (lympth)
  • this brings liquid back into blood
37
Q

Transpiration

A
  • the loss of water vapour from the stomata by evaporation
  • energy is supplied by sun (passive)
38
Q

factors that affect transpiration

A
  • humidity (negative correlation. more water vapour in air = water potential more positive on outside of leaf so reduces water potential gradient)
  • light (positive correlation, stomata open so large sa)
  • temperature (positive correlation. kinetic energy)
  • wind (positive correlation, blows away water vapour so maintains conc grad)
39
Q

Movement of water across the cells of a leaf

A
  • mesophyll cells lose water in airspcaes by evaporation
  • these cells now have a lower water potential and so water enters neighbouring cells by osmosis
  • and again
40
Q

Cohesion-tension theory

A
  • COHESION water is dipolar (negative O, positive H) so causes hydrogen bonds to form between h and o of water molecules.so stick together and so water travels up the xylem in continous water column
  • CAPILLARITY. adhesion. water sticks to the xylem walls, the narrower the xylem the bigger the impact of capillarity.
  • ROOT PRESSURE: water moves into root by osmosis so increases volume so increases pressure and forces water above it upwards (positive pressure).
41
Q

Movement of water up the xylem

A
  • water vapour evaporates out stomata which lowers water pressure
  • when this waters lost by transpiration, more water moves upwards to replace it
  • due to hydrogen bonds, waters cohesive so it creates a column of water up the xylem.
  • also adhere so stick to walls
  • as water moves upwards it creates tension which pulls xylem in to become narrower
42
Q

Phloem tissue is made up of two key cells:

A
  • sieve tube elements (living, no nucleus)
  • companion cells (provide atp for active transport)
43
Q

Mass flow hypothesis

A
  • transports organic substances in plants, mass flow from the source of production (leaves) to the sink (where the organic substances are used in respiring tissues)
44
Q

Translocation process

A

1) transfer of sucrose from photosythesing tissue to the sieve elements
2) mass flow of sucrose through sieve tube elements

45
Q

Transfer of sucrose from photsynthesising tissue to the sieve tube elements

A
  • sucrose is manufactured, from products of photosynthesis in chloroplasts of cells
  • sucrose diffuses down a concentration gradient by facilitated diffusion from photosynthesising cells to companion cells
  • hydrogen ions actively transported from companion cells to spaces in cell wall using ATP
  • these hydrogen ions diffuse down a concentration gradient through carrier proteins into sieve tube elements
  • sucrose molecules transported along with hydrogen ions through co-transport
46
Q

Mass flow of sucrose through sieve-tube elements

A
  • sieve tubes have lower water potential
  • water xylem has high water potential so water moves into sieve tubes by osmosis which creates high hydrostatic pressure
  • at respiring cells, sucrose either used by respiration or storage
  • so they have low sucrose content and so sucrose is acitvely transported in from sieve tube elements lowering the water potential
  • this causes water to move into respiring cells too by osmosis
  • so hydrostatic pressure in sieve tubes is lowered and is lower at sink and high at source where waters moving in
47
Q

evidence for and against mass flow hypothesis

A

FOR:
pressure in sieve tubes as sap released when cut. concentration of sucrose is higher in leaves than roots. many mitochondria and atp in companion cells.

AGAINST:
- not all solutes move at same pace
- sucrose goes to all regions at same rate, rather than those with lowest concentration

48
Q

investigating transport in plants

A
  • ringing experiments; outerlayer (bark) is removed, above swells and build up of organic substances
  • tracer experiments; radioactive isotopes traced as they move within the plant using autoradiography

Biology Paper 1 (10 decks)

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