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biology - component 3 > transport of gases > Flashcards

transport of gases Flashcards

1
Q

what is the function of blood?

A
  • allows gas exchange and delivery of important molecules (e.g glucose and oxygen)
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2
Q

what is blood?

A

a tissue compromising blood cells suspended in a straw-coloured fluid called plasma

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3
Q

what materials are in plasma?

A

glucose
amino acids
salts
hormones
urea
proteins

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4
Q

what is the function of plasma?

A

transports hormones antibodies and other proteins as well as distributing heat around the body

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5
Q

what are the three types of blood cell?

A
  • leucocytes (white blood cells)
  • thrombocytes (platelets)
  • erythrocytes- (red blood cells)
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6
Q

how many types of leucocytes are there?
what are they?
describe them

A

2 groups of immune cells :
1. GRANULOCTYES - have granular cytoplasm and lobed nuclei ; their function is to engulf pathogens by phagocytosis

  1. AGRANULOCYTES - produce antibodies and antitoxins, have a clear cytoplasm and spherical nucleus
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7
Q

what are erythrocytes filled with?

A

haemoglobin

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8
Q

what are the three important features which allow erythrocytes to efficiently transport oxygen?

A
  • they are biconcave in shape, which allows for increased surface area for diffusion of oxygen quickly
  • they do not contain a nucleus, so more room for haemoglobin which combines with oxygen (oxyhemoglobin)
  • flexible shape allows cells to squeeze through capillaries (shorter diffusion pathway)
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9
Q

describe the structure of haemoglobin

A

a complex globular protein, with a quaternary structure consisting of four folded polypeptide chains.
at the centre of each polypeptide chain is a haem group, which consists of Iron

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10
Q

what intermolecular forces could be found within haemoglobin?

A
  • ionic
  • hydrogen
  • disulphide
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11
Q

define affinity

A

the degree to which one molecule of haemoglobin is chemically attracted to another molecule (oxygen)

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12
Q

define saturation

A

the percentage of oxygen bound to haemoglobin

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13
Q

define association / loading

A

the uptake of oxygen by haemoglobin to form oxyhemoglobin at the lungs

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14
Q

define dissociation / unloading

A

the release of oxygen at the respiring tissues to form haemoglobin

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15
Q

what is oxygen measured in?

A

partial pressure
kPa

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16
Q

describe the link between partial pressure, affinity and association/dissociation

A
  • when the partial pressure of oxygen is HIGH (e.g in the lungs) haemoglobin has a HIGH affinity for oxygen so oxygen ASSOCIATES with haemoglobin to form oxyhemoglobin
  • when the partial pressure of oxygen is LOW (e.g in the respiring tissues) haemoglobin has a LOW affinity for oxygen and so oxygen DISSOCIATES from oxyhemoglobin, forming haemoglobin
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17
Q

what does the oxygen dissociation curve show?

A

shows the uptake of oxygen by haemoglobin at different partial pressures of oxygen

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18
Q

list the way in which the shape of the haemoglobin dissociation line differs from the theoretical line

A
  • the haemoglobin line is S - shaped
  • haemoglobin line rises more steeply between two points
  • theoretical line shows no flattening at the top
  • haemoglobin shows higher saturation throughout
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19
Q

what is cooperative binding?

A

the ease with which a haemoglobin molecule binds a second and then a third oxygen molecule, compared with the first and fourth

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20
Q

what is the shape of the oxygen dissociation curve?

A

sigmoid curve
s - shaped

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21
Q

describe cooperative binding

A
  • as haemoglobin is a protein, it changes shape when any molecules associates with it
  • it causes a change in the shape that makes second and third binding site MORE AVAILABLE, increasing haemoglobin affinity for oxygen. Therefore, the 2nd and 3rd oxygen molecule associate more easily than the first
  • it is then more difficult for an oxygen molecule to associate with the last binding site, therefore binding of oxygen to haemoglobin is not directly proportional to oxygen concentration
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22
Q

why is the partial pressure of oxygen low in respiring tissues?

A

it is being used in aerobic respiration

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23
Q

the oxygen saturation of haemoglobin measured in a healthy person is 98/99%.
why is not 100%?

A
  • some oxygen is used by the respiring cells of the alveoli
  • the rate of blood flow through the pulmonary capillaries is still to fast for all the oxygen to diffuse into the blood
24
Q

where is the oxygen dissociation for foetal haemoglobin in comparison to the adult curve?
what does this mean?

A

SHIFTS TO THE LEFT
this means that it has a higher affinity for oxygen and therefore can load oxygen from the mother’s blood at ALL partial pressures of oxygen

25
Q

why doesn’t a baby retain its foetal haemoglobin once it is born?

A
  • foetal haemoglobin has a higher oxygen affinity so not enough oxygen would be released to the respiring tissue of an adult
  • if female, when having own children the adult needs its haemoglobin to have lower affinity than the foetal haemoglobin
26
Q

where do llamas live?
how does this affect their haemoglobin?
why does it affect their haemoglobin?

A
  • they live at a high altitude
  • a llama’s haemoglobin has a higher affinity for oxygen and therefore picks up oxygen more readily at the lungs
  • with an increase in altitude, there is a drop in atmospheric pressure and therefore a reduction in the partial pressure of oxygen
27
Q

where is the oxygen dissociation for llama haemoglobin in comparison to the adult curve?

A

the curve is shifted to the LEFT

28
Q

where do lugworms live?
where do they obtain there oxygen from?
how do they cope with this environment?

A
  • they live in burrows in the sand on the seashore
  • they absorb oxygen from the seawater they pump through their burrow
  • the seawater has a very low oxygen concentration
  • this means that there is a higher affinity for oxygen so the haemoglobin more readily takes up oxygen
29
Q

where is the oxygen dissociation for lugworm haemoglobin in comparison to the adult curve?

A

the curve shifts to the LEFT

30
Q

what is myoglobin?
what is its function?

A
  • a tertiary structured protein that is more stable than haemoglobin
  • acts as an oxygen store in muscle tissue
31
Q

why is myoglobin more stable than haemoglobin?

A

myoglobin’s affinity for oxygen is higher than haemoglobin (this is because it consists of only one molecule of oxygen)

32
Q

where is the oxygen dissociation for myoglobin in comparison to the adult curve?

A

is shifts VERY FAR TO THE LEFT

33
Q

what could cause the partial pressure of oxygen to become very low?

A
  • muscle contraction
  • respiration
  • vigorous exercise
34
Q

describe the Bohr Effect

A
  • when the partial pressure of carbon dioxide is high, the conditions becomes more acidic
  • this causes the haemoglobin to change shape slightly and so haemoglobin now has a lower affinity for oxygen
  • unloading this oxygen to the respiring tissues more readily
35
Q

when would the partial pressure of carbon dioxide be high?

A

when carbon dioxide is produced in respiring tissues e.g contracting muscles

36
Q

where would the oxygen dissociation curve be moved to when the Bohr Effect takes place?

A

RIGHT

37
Q

explain why an increase in the rate of respiration would lead to more oxygen being released from oxyhemoglobin (4 marks)

A
  • more carbon dioxide is produced from respiration
  • this is known as the Bohr Effect
  • increases carbonic acid concentration
  • leads to increase in H+ concentration so there is an increase in acidicity
  • so there is a decrease in affinity of haemoglobin for oxygen so more oxygen is released from oxyhemoglobin
38
Q

name the vessel that removes excess tissue fluid

A

lymph

39
Q

explain why fluid will accumulate in the tissues of a person who diet is poor in protein (3 marks)

A
  • fewer plasma proteins in blood
  • this increases water potential of plasma
  • this reduces water potential gradient and hydrostatic pressure is greater than osmotic pressure
  • less water / fluid is re absorbed by osmosis
40
Q

explain why a very high oxygen affinity can be both an advantage and a disadvantage to lugworms (2 marks)

A

ADVANTAGE : can reach O2 saturation at low partial pressure of oxygen

DISADVANTAGE : oxygen is not released readily

41
Q

how is carbon dioxide transported in the blood?

A
  1. 10% binds to haemoglobin - transported as carbamino-haemoglobin
  2. 5% is dissolved in plasma
  3. 85% of the carbon dioxide carried in the blood is converted to hydrogen carbonate ions (HCO3 - ) and transported in plasma
42
Q

describe the chloride shift

A
  • co2 from respiring cells diffuses into plasma, then into red blood cells
  • co2 reacts with water to produce carbonic acid. this reaction is catalysed by the enzyme carbonic anhydrase
  • the carbonic acid dissociates into H+ and HCO3 - ions
  • the hydrogen carbonate ions diffuse down their concentration gradient into plasma
  • the hydrogen carbonate ions combine with Na+ ions in plasma to form sodium hydrogen carbonate
  • in the red blood cells, the accumulation of H+ ions from the dissociation of carbonic acid causes a fall in pH (more acidic)
  • this alters the haemoglobin, reducing its affinity for oxygen. H+ ions combine with haemoglobin to from haemoglobinic acid ; this releases the oxygen
  • the released oxygen diffuses out of the red blood cells into the respiring tissues
  • movement of negatively charged ions out of the red blood cells is balanced by the movement of chloride ions into the red blood cells from the plasma by facilitated diffusion
  • this maintains the electrochemical neutrality of the red blood cells
43
Q

how is the transport of carbon dioxide linked to the Bohr Effect?

A
  • the formation of carbonic acid and subsequent fall in pH inside the red blood cells explains the Bohr Effect
  • the high concentration of carbon dioxide produced by actively respiring tissues reduces the affinity of haemoglobin for oxygen and therefore enables cells requiring more oxygen to obtain it by promoting the dissociation of oxygen from oxyhaemoglobin in the red blood cells
44
Q

how are carbon dioxide and dissociation related?

A

the more carbon dioxide produced, the more acidic the conditions will be and so more oxygen will dissociate from the oxyhaemoglobin

45
Q

how are capillaries adapted to their function?

A
  • thin
  • large surface area for exchange of materials
  • blood flows slowly through capillaries allowing time for exchange of materials and increased friction
46
Q

describe how tissue fluid is formed?
3 MARKS

A
  • hydrostatic pressure is higher than osmotic pressure at the arterial end
  • this forces water and small soluble molecules out of the capillary
  • blood cells and larger protein molecules are retained in the capillary
47
Q

what is the function of tissue fluid?

A

bathes cells and allows exchange of gases and nutrients

48
Q

name some molecules required by cells

A

ions
glucose
amino acids
oxygen

49
Q

name some waste substances removed from cells

A

urea
carbon dioxide

50
Q

describe tissue fluid at the arterial end of the capillary

A
  • blood is under pressure from contraction of left ventricle. this creates high hydrostatic pressure and force fluid through gaps in the capillary walls
  • the outward flow of fluid is opposed by osmotic pressure (water trying to move back into the blood)
  • hydrostatic pressure is greater than osmotic pressure, so there is a net flow of fluid out of the blood
  • molecules dissolved in the tissue fluid move by (facilitated) diffusion into the cells down a concentration gradient
51
Q

describe tissue fluid at the venous end of capillary

A
  • tissue fluid contains waste substances that have diffused out of cells, these can diffuse back into the blood in capillaries
  • there is lower hydrostatic pressure due to friction between the blood and capillary wall and due to the lower volume of fluid
  • water potential is lowered due to plasma proteins so osmotic pressure is greater than hydrostatic pressure, so there is a net movement of water back into the blood
52
Q

what percentage of tissue fluid flows back into capillaries?

A

90%

53
Q

what is the lymphatic system involved in?

A
  • the absorption of lipids in the small intestine
  • the formation of lymphocytes and the prevention of disease
54
Q

what is lymph?

A

fluid from tissues which does not drain back into the capillaries of the circulatory system

55
Q

what percentage of tissue fluid drains into the lymphatic system?

A

10%

56
Q

explain why fluid will accumulate in the tissues of a person whose diet is poor in protein
3 MARKS

A
  • fewer plasma proteins in blood
  • this increases water potential of plasma
  • this reduces water potential gradient and hydrostatic pressure is greater than osmotic pressure
  • water / fluid is reabsorbed by osmosis
57
Q
A

biology - component 3 (8 decks)

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