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8- Transport in animals Flashcards

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1
Q

Why are specialised transport systems needed?

A
  1. metabolic rate - large multicellular organisms have high metabolic rates. Require large volumes of substances and produce lots off waste. Diffusion alone would not be able you intake and expel all of these substances
  2. the SA:V ratio gets smaller as organism gets bigger = increased diffusion distance = diffusion would occur too slowly. SA available to absorb and remove substances becomes relatively smaller
    3.molecules such as hormones or enzymes may be made in one place but needed in another
    4.food will be digested in one organ system but needs to be transported to every cell for use in respiration and other aspects of cell metabolisms
  3. waste products of metabolism need to be removed and transported to excretory organisms
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2
Q

What features do every circulatory system possess?

A

-liquid transport medium that circulates around the system (blood)
-vessels that carry the transport medium
-pumping mechanism/contractile device to move the fluid around the system

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3
Q

What is mass transport?

A

the bulk movement of substances through transport systems

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4
Q

What is an open circulatory system?

A

-very few vessels to contain the transport medium
-heart that pumps a fluid called haemolymph through short vessels and into a large cavity called the haemocel
-in the haemocel the transport medium is under low pressure and the haemolymph comes into direct contact with the cells and tissues where exchange takes place
-when heart relaxes haemolymph blood is sucked back in via pores called ostia
-haemolymph moves around organism due to movement
-haemolymph doesn’t carry oxygen and CO2 but transports food and nutrients

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5
Q

In what organisms is an open circulatory system found?

A

-molluscs
-arthropods

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6
Q

What is a closed circulatory system?

A

-blood is enclosed in blood vessels and does not come into direct contact with cell of the body
-the heart pumps blood around the body under pressure and relatively quickly
-blood is pumped through a series of progressively smaller vessels and returned back to the heart by progressively larger blood vessels
-substances leave and enter blood by diffusion through walls of blood vessels
-amount of blood flowing through vessels can be adjusted by widening + narrowing blood vessels

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7
Q

What organisms have closed circulatory systems?

A

-mammals
-vertebrates
-few invertebrates

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8
Q

What are single closed circulatory systems?

A

-heart with 2 chambers
-blood passes through the heart once for every circuit of the body
-blood passes through two sets of capillaries before it returns to heart

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9
Q

What organisms have single closed circulatory systems?

A

-fish
-annelid worms

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10
Q

What are double circulatory systems?

A

-heart has 4 chambers
-blood passes through the heart twice for every circuit of the body
-each circuit to the lungs and the body
-passes through one capillary network, relatively high pressure and fast flow

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11
Q

What organisms have double circulatory systems?

A

-birds
-most mammals

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12
Q

What are the advantages of single circulatory systems?

A

-less complex, does not require complex organs

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13
Q

What are the disadvantages of single circulatory systems?

A

-low blood pressure
-slow movement of blood
-activity level tends to be low

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14
Q

What are the advantages of double circulatory systems?

A

-heart can pump blood further around the body
-higher pressure
-faster blood flow

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15
Q

What is an exception for the disadvantages of single circulation?

A

-fish
-effective singe circulation meaning that they can be very active
-countercurrent exchange system and allow them to take up lots of oxygen from water

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16
Q

What are the five types of blood vessel?

A

-arteries
-arterioles
-capillaries
-venues
-veins

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17
Q

What are elastic fibres?

A

Composed of elastin and can stretch and recoil providing vessel with flexibility

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18
Q

What is smooth muscle do in blood vessels?

A

Vasoconstriction and vasodilation of to change the size of the lumen and intern control the flow of blood into capillaries

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19
Q

What does collagen do in blood vessels?

A

Provides structural support to maintain shape and volume of vessel

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20
Q

What is the structure of arteries?

A

-carry blood away from heart to tissues of the body
-oxygenated blood (except pulmonary artery and umbilical artery during pregnancy)
-narrow lumen to maintain high pressure
-thick muscular walls and elastic fibres which allows to stretch and recoil to maintain high pressure
-elastic fibres recoil which helps to even out blood pumped from heart to give continuous flow
-lining of artery contains endothelium which is smooth so blood easily flows over it

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21
Q

What is the structure of arterioles?

A

-link arteries and capillaries
-more smooth muscle and less elastin, but can constrict or dilate to control the flow of blood into individual organs

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22
Q

What is the structure of veins?

A

-carry blood towards the heart
-carry deoxygenated blood (except pulmonary vein and umbilical vein during pregnancy)
-wider lumen as blood pressure is low compared to arteries and to maximise volume of blood carried to heart
-endothelium lining which is smooth so blood flows easily
-valves to prevent back flow of blood
-thinner layers of muscle and elastin tissue as little need for stretching a recoiling
-lots of collagen to provide structural support
-thin walls, under low pressure
-when skeletal muscle contracts they compress veins, helping to increase pressure and push blood along

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23
Q

What are the 3 layers of arteries called?

A

Tunica intima
Tunica media
Tunica externa

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24
Q

What makes up the tunica intima?

A

squamous epithelium

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25
Q

What is the blood flow into arteries like?

A

-high pressure
-pulsatile
-fast

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26
Q

What is the structure of venules?

A

-link capillaries with veins
-very thin walls
-no smooth muscle or elastin fibres
-several venules will split from one vein

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27
Q

What is the structure of capillaries?

A

-smallest blood vessels
-site of substance exchange with cells
-very close to cells so small diffusion pathway
-walls are single endothelial cell thick for short diffusion pathway
-large surface area for diffusion of substance in and out of blood
-gaps called fenestrations between endothelial cells allow substances to diffuse out between
-large number of capillaries to increase surface area for gas exchange
-cross sectional area is small to reduce the rate of blood flow giving more time for the exchange of materials by diffusion between blood and the cells

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28
Q

What are pressure changes like within blood vessels?

A

-high to low pressure
-vena cava is the final blood vessel to return to the heart so has the lowest pressure
-pressure highest in the aorta
-blood looses pressure as it moves along the vessels from the aorta due to it branching into many vessels, increasing lumen size and friction
-fluctuations in blood pressure in arteries and arterioles as elastic tissue stretches when blood moves through at high pressure then recoils as blood pressure drops this helps to even out the flow

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29
Q

What is plasma?

A

liquid component of blood

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30
Q

What is the function of plasma?

A

transport dissolved substances
eg. glucose, amino acids, hormones, fibrinogens

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31
Q

Why is albumin important?

A

it helps to maintain osmotic pressure

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32
Q

Why are fibrinogens important?

A

important in blood clotting

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33
Q

What are platelets?

A

small fragments of cells

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34
Q

What is the function of platelets?

A

start the process of blood clotting

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35
Q

What is the function of erythrocytes?

A

carry oxygen and carbon dioxide around the blood

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36
Q

What are the characteristics of granulocytes?

A

-lobed nucleus
-granular cytoplasm

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37
Q

What is the function of monocytes?

A

involved in defence against pathogens

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38
Q

What are the functions of blood as a whole?

A

-transport of oxygen and carbon dioxide to and from respiring cells
-transport digested food from the small intestine
-transport nitrogenous waste products from cells to the excretory organs
-transport chemical messages (hormones)
-transport cells and antibodies involved in immune response
-platelets to damaged areas
-acts as a buffer to minimise pH changes

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39
Q

What are the 3 layers of the artery called?

A

Tunica intima
Tunica media
Tunica externa

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40
Q

What makes up the tunica initima?

A

squamous epithelial

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41
Q

What is the function of arteries?

A

Carry oxygenated blood away from the heart (apart from pulmonary artery)

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42
Q

Why do arteries need to maintain high pressure of the arteries?

A

so that blood can reach tissues in the body

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43
Q

What makes up the tunica media of the arteries?

A

smooth muscle and elastic fibres

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44
Q

What makes up the tunica externa of arteries?

A

collagen

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45
Q

What do the elastic fibres in the tunica media of the arteries do?

A

stretch to receive blood and recoil between contractions of the heart which helps to maintain pressure and even out blood flow

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46
Q

What is the function of collagen in the tunica externa of arteries?

A

prevents blood vessels from bursting under high pressure

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47
Q

why is the tunica initima of the arteries smooth?

A

so blood flows easily over it

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48
Q

What is the function of arterioles?

A

regulate the flow of blood into capillaries

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49
Q

Why do arterioles have a lower proportion of elastin in their walls compared to arteries?

A

the blood flow isn’t very pulsatile

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50
Q

What is the function of capillaries?

A

to exchange substances between blood and tissues

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51
Q

What is the advantage of capillaries being one cell thick

A

short diffusion pathway

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52
Q

What is the advantage of blood flow being slow through capillaries?

A

gives longer time for exchange of substances

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53
Q

Why is blood flow low pressure through capillaries?

A

-prevent them from bursting
-pressure is spread across many vessels

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54
Q

What is the function of venules?

A

to link capillaries to veins

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55
Q

What are the walls of venules mostly made of?

A

collagen

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56
Q

Why do ventless have a thin tunica media?

A

low pressure flow doesn’t require muscle or elastic fibres

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57
Q

Why do veins have a wide lumen?

A

to accommodate the large volume of blood carried

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58
Q

Why are valves present in veins?

A

prevent backflow

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59
Q

What 3 mechanisms aid blood flow back to the heart?

A

-movement of skeletal muscles contract/relax and push blood through veins as they lie near the surface
-pocket valves = prevent back low
-breathing mechanism causes negative pressure in the thorax so pulls blood towards the heart

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60
Q

What is the function of lymphocytes?

A

produce antibodies and antitoxins

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61
Q

What is lymph?

A

modified tissue fluid that is collected in the lymphatic system

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62
Q

What is tissue fluid?

A

-a liquid produced from the circulatory system which contains dissolved nutrients
-formed at the arterial end of a capillary
-flows over cells and provides useful substances and removes waste substances

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63
Q

What is the function of tissue fluid?

A
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64
Q

What % of the total volume of blood is plasma?

A

55%

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65
Q

What % of the total volume of blood is red blood cells?

A

45%

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66
Q

How is a red blood cell adapted for its function?

A

-flattened bionconcave shape = increases there surface area = increased diffusion of oxygen
-flexible so can change shape and pass through narrow capillaries
-no nucleus to maximise the space for more haemoglobin
-packed with haemoglobin which binds to oxygen
-contain carbonic anhydrase to transport CO2 in the form of carboxyhaemoglobin
-haemoglobin carries oxygen, it is able to carry 4 molecules of O2

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67
Q

What causes sickle cell anaemia?

A

-mishappen red blood cells
-smaller volume so cannot carry as much haemoglobin = cannot carry oxygen
-diffusion of oxygen slower as it has a smaller surface area

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68
Q

How do you calculate filtration pressure?

A

hydrostatic pressure - oncotic pressure

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69
Q

What is oncotic pressure?

A

The tendency of water to move into the blood from surrounding tissues by osmosis

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70
Q

What is the value of oncotic pressure?

A

-3.3 kPa

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71
Q

What is hydrostatic pressure?

A

The high pressure inside the blood caused by surge of blood that occurs every time the heart contracts

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72
Q

What is the value of hydrostatic pressure?

A

arteriole end - 4.6 kPa
venue end - 2.3 kPa

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73
Q

What happens to fluid at the arterial end of the capillary?

A

-hydrostatic pressure is relatively high (4.6 kPa)
-higher then oncotic pressure attracting water in by osmosis
-fluid is squeezed out of the capillaries

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74
Q

How does the composition of tissue fluid differ from plasma?

A

-no red blood cells
-no plasma proteins

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75
Q

What happens at the venue end of the capillaries?

A

-hydrostatic pressure falls to around 2.3 kPa as fluid has moved out and the pulse is completely lost
-oncotic pressure is still -3.3kPa
-oncotic pressure is higher then hydrostatic pressure
-water moves back into the venous end of capillaries
-some tissue fluid is reabsorbed

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76
Q

Describe the formation of tissue fluid?

A
  1. At the arteriole end of the capillary, the hydrostatic pressure (4.6 kPa) inside the capillaries is greater than in the tissue fluid and also greater than the osmotic pressure (-3.3 kpa)
  2. The difference in hydrostatic pressure forces fluid containing small molecules (nutrients and oxygen) out of the blood through tiny gaps in the capillary wall. This forms tissue fluid
  3. Red blood cells, platelets and plasma proteins remain in the blood as they are too large to be pushed out through capillary walls
  4. Exchange occurs between tissue fluid and cells by diffusion, facilitated diffusion and active transport. Oxygen and nutrients enter the cells and CO2 send other waste leave the cell and enter tissue fluid
  5. As fluid leaves the capillaries at arteriole end it reduces the hydrostatic pressure. This means the blood pressure at the venous end of capillaries is much lower
  6. As water leaves the capillary but the plasma proteins can’t leave this lowers the water potential of the blood. Therefore the water potential in the capillary is lower than in the tissue fluid at the venule end. So at the venule end the osmotic pressure (-3.3 kPa) becomes greater then the hydrostatic pressure (2.3 kPa) so water moves into the capillary buy osmosis carrying carbon dioxide and waste products
  7. Any excess tissue fluid that is not reabsorbed is returned and collected into the lymphatic system which returns it to the circulatory system
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77
Q

How much tissue fluid remains in tissues and is not reabsorbed?

A

10%

78
Q

What is the lymphatic system made up of?

A

-lymphatic capillaries
-lymph vessels (veins)
-lymphoid organs (lymph nodes, spleen, thymus, tonsils. adenoids

79
Q

What is the function of the lymphatic system?

A

Supplements the circulatory system by returning excess tissue fluid to the blood stream

80
Q

What is lymph?

A

excess tissue fluid that is drained into the lymphatic system

81
Q

What colour is lymph?

A

colourless/ pale yellow

82
Q

Where does the lymphatic system drain?

A

-Into the circulatory system near the vena cava
-Via the thoracic duct

83
Q

What would happen if we did not have a lymphatic system?

A

-die within 24 hours
-rate of water loss in the blood would be too large = build up of tissue fluid in the tissues (oedema)

84
Q

What are enlarged lymph nodes a sign of?

A

-sign that your body is fighting an invading pathogen

85
Q

What is tachycardia?

A

when the heartbeat is rapid, over 100bpm

86
Q

When is tachycardia normal?

A

-when exercising
-have a fever
-frightened or angry

87
Q

What is bradycardia?

A

When the heart rate slows down to below 60bpm

88
Q

Why do elite athletes often have bradycardia?

A

-training makes the heart beat more slowly and efficiently

89
Q

What is an ectopic heartbeat?

A

extra heartbeats that are out of normal rhythm

90
Q

What is atrial fibrillation?

A

-abnormal rhythm of the heart
-abnormal rhythm of the atria which is then passed onto the ventricles which contract much less often and resulting in the heart not pumping blood effectively

91
Q

What is the function of pericardium in the heart?

A

inelastic and prevents the heart from overstretching or overfilling with blood

92
Q

Outline the movement of blood through the heart

A

-vena cava into the right atrium
-through tricuspid AV value
-right ventricle
-semilunar valves
-pulmonary artery
-lungs
-pulmonary vein
-left atrium
-bicuspid valve
-left ventricle
-semilunar valves
-aorta

93
Q

What is the heart made out of?

A

cardiac muscle, which contracts and relaxes in regular rhythm

94
Q

What is the difference between cardiac and skeletal muscle?

A

Cardiac muscle does not get fatigued and need to rest

95
Q

Why is the heart described as double pump?

A

-blood is pumped through the heart twice for every circuit
-first time deoxygenated blood is pumped to the lungs
-second time oxygenated blood is pumped to the body

96
Q

What is the function of the coronary arteries?

A

Supply the cardiac muscle with oxygenated blood (and glucose) in order to keep it contracting and relaxing all the time

97
Q

What is the function of pericardial membranes?

A

help prevent the heart from over distending with blood

98
Q

Is the wall of the left ventricle thicker than the right?

A

Yes, left side is thicker

99
Q

Why is the wall of the right ventricle thinner than the wall of the left ventricle?

A

-the right side only has to pump blood to the lungs which are close to the heart
-right side must only overcome resistance of pulmonary circulation

100
Q

Why is the wall of the left ventricle thicker than the wall of the right ventricle?

A

-left side must provide sufficient force to overcome the resistance of the aorta and arterial systems of the whole body
-left side must move blood under pressure to all extremities of the body

101
Q

As the atrium fills with blood what happen to the atrial pressure?

A

It increases

102
Q

How is cardiac muscle described?

A

Myogenic

103
Q

What does myogenic mean?

A

Heart muscle has its own intrinsic rhythm

104
Q

As ventricular pressure increases, what happens to aortic pressure? Why?

A

It increases
Blood flows into the aorta at high pressure

105
Q

What is the sino-atrial node? and what is its function?

A

Region of the heart that initiates the heartbeat by producing a wave of excitation which triggers the contraction of the heart (atria)

106
Q

What is the atria-ventricular node? and what is its function?

A

Picks up the wave of excitation from the SA node, imposes a slight delay and sends it own wave of depolarisation down the bundle of his and into the Purkunje fibres causing the ventricles to contract

107
Q

Why does the AV node impose a slight delay?

A

To ensure atrial contraction is complete

108
Q

What is the bundle of His?

A

conducting tissue made of purkunje fibres that pass through the septum

109
Q

What are purkunje fibres?

A

tissue that conducts the wave of excitation to the apex of the heart

110
Q

What is the function of the septum?

A

Prevents mixing of oxygenated and deoxygenated blood

111
Q

What is the function of the valves in the heart?

A

Prevent backlog of blood and so ensure efficient movement of blood

112
Q

What is the function of the tendinous cords?

A

Connect papillary muscles to the valves and help to prevent prolapse of the valves

113
Q

Why does hydrostatic pressure of blood drop ad blood moves away from the heart?

A

-divides into smaller vessels
-vessels have a large total cross sectional area
-loss of plasma from capillaries

114
Q

Outline the movement of electrical signals through the heart?

A

-Wave of depolarisation (excitation) begins at the SAN which causes the atria to contract
-Wave of depolarisation (excitation) travels to the AVN
-AVN imposes a slight delay before stimulating the bundle of His
-Bundle of His splits into two branches and conducts wave of excitation to the apex of the heart
-At apex Purkunje Fibres spread out through ventricular walls
-Spread of excitation triggers the contraction of the ventricles starting at the apex

115
Q

Why can a wave of depolarisation not travel directly to the ventricles?

A

There is a ring of non-conducting tissue between the atria and the ventricles

116
Q

Why is it important that the AV node imposes a slight delay?

A

-ensure the atria contract fully before the ventricles
- all atrial blood is emptied into ventricles before they contract

117
Q

Why do ventricles contract from the apex up?

A

-blood needs to be moved upwards
-ensures complete emptying of ventricles

118
Q

What is the affect on the heart of the vagus nerve releasing acetyl choline?

A

heart rate decreases

119
Q

What does ECG stand for?

A

Electrocardiogram

120
Q

What does an ECG show?

A

Shows the spread of electrical excitation through the heart as a way of recording what happens as it contracts

121
Q

What is on the x asis on an ECG?

A

Time

122
Q

What is on the y axis of an ECG?

A

Electrical potential (mV)

123
Q

What does the P wave on an ECG show?

A

Depolarisation of atria in response to SA node triggering atria to contract

124
Q

What does the QRS wave on an ECG show?

A

-ventricular systole
-wave of depolarisation in ventricle walls
-ventricles contract
-AV valves close

125
Q

What does the T wave on the ECG show?

A

-ventricles relax (diastole)

126
Q

How can heart rate be measured using an ECG?

A

heart rate is the time between peaks (R)

127
Q

What is the cardiac cycle?

A

The sequence of events that occur in the heart during one heartbeat

128
Q

What occurs during atrial systole?

A

-atria contract, ventricles relax
-as atria contract this decreases there volume so increases pressure
-atrial pressure is higher then ventricular pressure so the AV valves open
-semi-lunar valves are still closed
-blood flows into the ventricles
-atrial pressure decreases

129
Q

What occurs during ventricular systole?

A

-atria relax, ventricles fill with blood and contract
-ventricles contract decreasing volume and increasing pressure
-AV valves close so blood isn’t forced back into atria
-pressure inside ventricles increase
-semi-lunar valves open which forces blood into the aorta/pulmonary artery
-so pressure in ventricles decreases

130
Q

What occurs during diastole?

A

-atria and ventricles relax
-pressure in artieries is higher then ventricular pressure
-SL valves shut
-blood flows into atria from vena cava and pulmonary vein

131
Q

What causes the heart sounds?

A

blood hitting the valves

132
Q

What causes the ‘lub’ sound?

A

blood hitting AV valves as ventricles contract

133
Q

What causes the ‘dub’ sound?

A

backflow of blood hitting the semilunar valves

134
Q

What happens when the ventricular pressure is greater the artial pressure?

A

-AV valves close
-Systole is entered

135
Q

Why do the semilunar valves open?

A

-pressure in the ventricles is higher then arteries

136
Q

Why do the semilunar valves close?

A

-pressure in the ventricles drops below the pressure in the aorta

137
Q

Why do the AV valves open?

A

-pressure in the atria is greater then ventricular pressure

138
Q

As the ventricles contract what happens to the ventricular volume and pressure?

A

Volume decreases
Pressure increases

139
Q

What is arrhythmia?

A

Abnormal rhythm of the heart

140
Q

How are ECG’s measured?

A

-electrodes stuck on the skin
-measure electrical differences in the skin
-signal fed into machine which produces an ECG

141
Q

What is systole?

A

period of contraction

142
Q

What is diastole?

A

period of relaxation

143
Q

Does diastole or systole normally take longer?

A

Diastole is normally longer then systole

144
Q

What is the definition of stroke voulume?

A

The volume of blood pumped by the left ventricle in each heart beat

typical value of adult at rest = 75ml

145
Q

What is the definition of heart rate?

A

the number of times the heart beats per minute

typical value of adult at rest - 70bpm

146
Q

What does cardiac volume depend on?

A

-stroke volume
-heart rate

147
Q

What is the equation to work out cardiac output?

A

cardiac output = stroke volume x heart rate

148
Q

When is an artificial pacemaker used?

A

-when someone’s hearts electrical conduction system is not working properly
-problems include SAN not firing , blockage of impulses between SAN and AVN

149
Q

What do pacemakers do?

A

Monitor the hearts electrical activity and stimulate the ventricles or arterial to contract when necessary. Impulses are transmitted down electrodes implanted in the muscular walls

150
Q

How many oxygen molecules is one haem group able to carry?

A

1 oxygen molecule

151
Q

How many heam groups does one haemoglobin molecule contain?

A

4

152
Q

What is the equation for haemoglobin binding to Oxygen?

A

Hb + 4O2 ⇋ HbO8

153
Q

What is formed when haemoglobin binds to oxygen?

A

Oxyhaemoglobin

154
Q

How does oxygen get from the alveoli into the blood?

A

Diffuses from alveoli into blood down a concentration gradient

155
Q

What occurs to the Hb once the first oxygen molecule has been taken up by it?

A

The Hb changes shape

156
Q

Why does the Hb change shape once the first molecule of O2 has been taken up?

A

-enables Hb to take up three 2nd O2 more quickly
-the 3rd O2 quicker still
-4th O2 even more quickly
-allows a concentration gradient to be maintained as no free oxygen is dissolved into blood

157
Q

What is positive cooperactivity?

A

-Hb which changes shape once the 1st molecule of O2 is taken up
-Enables 2nd,3rd and 4th O2 molecules to be taken up more quickly

158
Q

Where is oxyhaemoglobin transported to?

A

Respiring tissues

159
Q

When oxyhaemoglobin is transported to respiring tissues what happens?

A

It releases O2 molecules

160
Q

What is the determining factor for whether O2 is picked up or released?

A

The partial pressure of O2 (pO2)

161
Q

What is an oxygen dissociation curve?

A

a way of showing how the binding of O2 varies at different pO2

162
Q

Is the pO2 greater in the lungs than in the capillaries of respiring tissues?

A

Yes

163
Q

What is the shape of the oxygen dissociation curve?

A

S shape

164
Q

What is the x axis for an oxygen dissociation curve?

A

p(O2) (kPa)

165
Q

What is the y axis for an oxygen dissociation curve?

A

% saturation of Hb with O2

166
Q

Why can the oxygen saturation of blood never be 100%?

A

Some Hb will be bound to CO2

167
Q

What is the effect of as drop of oxygen levels on Hb?

A

Causes O2 to be released from Hb

168
Q

Under what condition is Hb able to released more O2?

A

-increase in CO2 concentration
-increase in temperature
-increase in blood pH

169
Q

How is Hb able to release more O2 under certain conditions?

A

Oxygen dissociation curve shifts to the right

170
Q

What is the Bohr shift?

A

the movement of the oxygen dissociation curve to the right

171
Q

How does the Hb of an organisms that live in an environment of relatively low oxygen compare to organism living in normal environment?

A

Organism in low O2 environment:

-higher affinity for oxygen as less O2 is available is they have to take oxygen up easier and release it less easily
curve shifts to the left

172
Q

What is the effect of Hb with a higher affinity for O2 on the oxygen dissociation curve?

A

Shifts left

173
Q

Given an example of an organism that has a Hb with a higher affinity

A

A foetus

174
Q

Where does a foetus obtain its oxygen from?

A

Maternal Haemoglobin

175
Q

What is an advantage of respiring cells producing large amounts of CO2

A

-Curve is shifted right
-More oxygen can be released from the haemoglobin

176
Q

Why does foetal haemoglobin have a higher affinity of oxygen?

A

-Feotus is obtains is 02 from maternal haemoglobin
-in the present of maternal Hb releases the O2, which diffuses into the fetal bloodstream
-at the PO2, which maternal HB releases oxygen which diffuses into the fetal bloodstream
-PO2 at which maternal Hb releases O2, the fetus HB is able to pick it up

177
Q

what are the differences in affinity in maternal and fetal Hb? Why are there these differences?

A

-Fetal, HB has a higher affinity
-If the fetal and maternal haemoglobin had the same affinity for oxygen, there would be no incentive for the oxygen to switch from maternal blood to fetal blood

178
Q

What percentage of carbon dioxide is transported in blood plasma?

A

5%

179
Q

what are the 3 ways CO2 transport occurs?

A

-in the blood plasma (5%)
-Attaches to the immune group of haemoglobin (10-20%)
-Transported as hydrogen carbonate in red blood cells (75-85%)

180
Q

how is CO2 transported in blood plasma?

A

-Carbon dioxide dissolves into blood plasma to form carbonic acid
-The acid dissolves to give hydrogen carbonate ions and protons

181
Q

What is the function of plasma proteins in blood in regards to CO2 transport?

A

-buffer the protons
-and so protect the pH from decreasing and denaturing proteins in the blood

182
Q

What is the equation for CO2 transport in blood plasma?

A

CO2 + H20 ⇋ H2CO3 ⇋ H+ + HCO3-

183
Q

How is CO2 transported in red blood cells?

A

-CO2 diffuses into red blood cells
-Enzyme, carbonic anhydrase catalyses the reaction of CO2 and water to produce carbonic acid
-carbonic acid dissociates into HCO3- ions and H+
-HCO3- diffuse into plasma
-H+ buffered by Hb to form haemoglobic triggering the release of 402 molecules

184
Q

what is the chloride shift?

A

-due to HCO3- ions diffusing out of the cell down a concentration gradient charge becomes imbalanced
-to maintain electrical charge there is a inward diffusion of chlorine ions

185
Q

What happens to the processes of CO2 transportation when the lungs are reached?

A

-Low concentration of carbon dioxide, so carbonic anhydrase reverses the reaction, breaking down, carbonic acid into carbon dioxide and water
-Hydrogen carbonate ions diffuse back into the RBC’s and react with hydrogen atoms to form more carbonic acid
-Chlorine ions diffuse out of the red blood cells into the plasma down a electrochemical gradient

186
Q

What is the relative position of the fetal haemoglobin curve in comparison to the adult haemoglobin curve?

A

The fetal curve is to the left

187
Q

why is the fetal haemoglobin curve to the left of adult haemoglobin curve?

A

-placenta has low PO2
-Adult Hb wil release O2
-fetal haemoglobin is still able to take up some O2 in the placenta
-Fetal Hb has a higher affinity for oxygen then adult Hb

188
Q

what is the dissociation curve like for smaller organisms with a high SA:V with a high metabolic rate? and why?

A

-Low affinity for oxygen
-Diffusion curve to the right

-High metabolic rate= more respiration,= greater oxygen demand,= organisms, need haemoglobin with lower affinity for oxygen as they need to unload it quickly to meet the demands and allow a higher respiration rate-

189
Q

what is the dissociation curve like for myoglobin? and why?

A

-myoglobin has a high affinity for oxygen, even at low, partial pressures
-curve is very much to the left
-this means that oxymyoglobin will only dissociate when oxygen levels are low, it is found in muscle cell where it acts as an oxygen reserve

190
Q

what is a structure of haemoglobin like?

A

-Large globular protein
-quaternary structure - made up of four polypeptide chains
-Each chain has a haem group which contains an iron ion (Fe2+) which gives haemoglobin its red colour
-Each molecule of haemoglobin can bind to 4 oxygen molecules

191
Q

How does the partial pressure of carbon dioxide affect the affinity of haemoglobin for oxygen?

A

-if pCO2 is high (eg. in respiring tissues) Oxygen dissociates from haemoglobin more easily
-This allows oxygen to be unloaded to cells during intense activity

Biology (11 decks)

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