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Biology A level > 3.4 Mass transport in animals > Flashcards

3.4 Mass transport in animals Flashcards

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1
Q

What are 4 features of a transport system?

A

suitable medium in which to carry materials
a form of mass transport in which the medium is moved around in bulk over large distances
closed system of tubular vessels that contain medium and froms a branching network to distribute to all parts of the organism
a mechanism for moving medium within vessels - pressure differences

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2
Q

Why have multicellular organisms developed a circulatory system?

A

they cannot rely on diffusion alone to transport substances

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3
Q

what is mass flow?

A

molecules are carried in the flow of fluid, the flow is generated by a force which is produced by a pump

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4
Q

What are the 3 parts of a circulatory system?

A

transport fluid - plasma and tissue fluid
a pump - heart
series of tubes - vessels

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5
Q

What does closed, double circulatory system mean?

A

blood is confined to vessels and it passes through the heart x2 per 1 circuit

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6
Q

Why does blood pass through the heart twice?

A

when blood passes through the lungs, its pressure is reduced so the pressure needs to rise again

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7
Q

Why is exchange from blood vessels to cells rapid?

A

diffusion takes place over a large SA and a short distance and a steep diffusion grad

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8
Q

Which side of the heart transports oxygenated blood?

A

left

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9
Q

Which side of the heart transports deoxy blood?

A

right

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10
Q

What happens to oxygnated blood in a double ciculatory system?

A

oxy blood from gas exchange surface passes through the heart before going to the tissues

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11
Q

What happens during a single circulatory system?

A

blood passes through the heart once per cycle
only transports deoxy blood
oxy blood from gas exchange surface goes directly to tissues

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12
Q

What are the advantages of double ciculation?

A

prevents low blood pressures - blood pressures falls in the capillaries
better blood flow for O2 distribution for respiration

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13
Q

Why does pressure drop in the capillaries?

A

the dilation of the arterioles - increase in vol = decrease in pressure

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14
Q

What is pulmonary cicuit?

A

cirulation between the heart and lungs
lungs to heart - oxy blood via veins
heart to lungs - deoxy blood via arteries

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15
Q

What is systemic ciculation?

A

circulation between the heart and body tissues
heart - body tissues = oxy blood via arteries
body tissues - heart = deoxy blood via veins

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16
Q

What does the right side of the heart do?

A

pumps blood around the pulmonary circuit to re-oxygenate blood after returning from body tissues
body tissues –> vena cava –> right atrium and ventricle –> pulmonary artery
deoxy blood in right side, high in CO2

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17
Q

What is the vena cava?

A

a large vein that collects blood from the systemic circuit

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18
Q

What does the left side of the heart do?

A

pumps blood around the systemic cicuit to deliver O2 to respiring body tissues
oxy blood
pulmonary vein –> left atrium and ventricle –> aorta

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19
Q

What direction do veins usually carry blood?

A

towards the heart

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20
Q

What direction do arteries usually carry blood?

A

away from the heart

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21
Q

How does blood go into the coronary arteries?

A

by the aorta

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22
Q

Where is the CO2 produced by the heart drained?

A

into the cardiac veins

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23
Q

What are the atria?

A

they are thin-walled elastic chambers that recieve blood from the veins

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24
Q

Why do the atria have thin walls?

A

they need to be able to expand to fill up with more blood

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25
Q

What are ventricles?

A

thick-walled chambers that pump blood out of the heart through the arteries

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26
Q

Why are the ventricles thick walled?

A

they pump blood further distances so it needs a higher pressure to sustain this distance around the body

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27
Q

How are the artia and ventricle separated?

A

by atrio-ventricular valves

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28
Q

How are the artieries leading from the heart and the ventricles separated?

A

semi-lunar valves

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29
Q

How is the cardiac muscle different to other muscles?

A

it can contract without a signal from the brain - automatic contraction

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30
Q

What is cardiac muscle?

A

a specialised type of muscle found in the walls of the heart

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31
Q

What do the coronary arteries do?

A

they deliver O2 and nutrients to the heart tissue

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32
Q

What does the cardiac muscle consist of?

A

branched myofibrils which are separated by intercalated discs

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33
Q

What are all the structures of the heart? (top left to top right of the heart)

A

left pulomonary artery
pulmonary vein
left artium
semi-lunar valve
atrio-ventricular valve - bicuspid
left ventricle
tendon
papillary muscle
septum
right ventricle
atrio-ventricular valves - tricuspid
inferior vena cava
right atrium
right pulomonary artery
aorta
superior vena cava

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34
Q

What do valve tendons do?

A

prevents valves from inverting

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35
Q

Where does the blood return to the heart from the systemic circuit?

A

right side
superior vena cava and inferior vena cava

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36
Q

Where does blood leave the heart to the pulmonary circuit?

A

from the left pulmonary artery

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37
Q

Where does blood return from the pulmonary circuit?

A

the pulmonary veins

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38
Q

Where does blood leave to the systemic circuit?

A

the aorta

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39
Q

What does TS stand for?

A

transverse section

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40
Q

Why does the bicuspid valve need to be replaced and the tricuspid valve doesnt?

A

the left side of the heart is a stronger muscle and thicker walls
the bicuspid is exposed to higher pressures

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41
Q

What symptom would someone have in their bicuspid valve was failing?

A

oxy blood would not travel around the body - irregular heartbeat
causes a shortness of breath and fatigue

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42
Q

What is cardiac output?

A

the volume of blood pumped out of the heart per minute

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43
Q

What is the cardiac output equation?

A

cardiac output = stroke volume x heart rate

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44
Q

What is the stroke volume?

A

the volume of blood pumped by the left ventricle every heart beat

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45
Q

What do coronary veins do?

A

they return deoxy blood from the cardiac muscle tissue by the vena cava

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46
Q

What will blockages of the coronary arteries cause?

A

a heart attack = an area of the heart is deprived of blood therefore deprived of O2, the muscle cells are unable to respire

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47
Q

What is the cardiac cycle?

A

the sequence of events that occur in 1 heartbeat, consists of contraction and relaxation

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48
Q

What does systole mean?

A

contraction

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49
Q

What does diastole mean?

A

relaxation

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50
Q

What direction does blood flow?

A

down a pressure grad

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51
Q

What happens during atrial systole?

A

the volume of the atria decreases
the pressure of the artia increases
the blood flows from the atria to the ventricles
the AV valves are open - due to pressure grad from atria–> ventricles
the SL valves are closed - due to pressure grad from arteries –> ventricles ( pressure is higher in the arteries)

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52
Q

What happens during ventricular systole?

A

the volume of the ventricles decreases
the pressure in the ventricles increases
the blood flows from ventricles –> arteries
the AV valves are closed - due to pressure grad from ventricles to atria
the SL valves are open - due to pressure grad from ventricles –> artery

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53
Q

What happens during diastole?

A

the whole heart is relaxed
the volume of the heart increases
the pressure in the heart decreases
the blood fills all the chambers
the AV valves are open - due to pressure grad from atria to ventricles
the SL valves are closed - due to pressure grad from arteries to ventricles

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54
Q

How long is atrial systole?

A

0.2 secs

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55
Q

How long is ventricular systole?

A

on graph - 0.2 - 0.4 secs
so lasts 0.2 secs

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56
Q

How long is diastole?

A

on graph - 0.4-0.8
so lasts 0.4 secs

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57
Q

Where on the cardiac cycle graph do the valves open/ close?

A

when the lines intercept

58
Q

What do the atrio-ventricular valves do?

A

prevent the backflow of blood when contraction of the ventricles means the ventricular pressure exceeds atrial pressure

59
Q

What do the semi-lunar valves do?

A

they prevent the backflow of blood into the ventricles from the arteries when the pressure in the arteries exceeds the pressue in the ventricles

60
Q

How does aortic pressure exceed the ventricular pressure?

A

when the elastic walls of the arteries recoil increasing their pressure and the ventricular walls relax and have lower pressure

61
Q

What are pocket valves?

A

the valves in veins that ensure that when veins are squeezed, the blood flows towards the heart

62
Q

What is the advantage of transporting blood in vessels?

A

it allows the blood to be pumped at high pressures delivering nutrients and removing waste more efficently

63
Q

What are the 5 types of blood vessels?

A

arteries
arterioles
capillaries
venules
veins

64
Q

What does the elastic tissue in blood vessels (arteries and arterioles) do?

A

expands and contracts to maintain blood pressure

65
Q

What does the smooth muscle do in the artery?

A

keeps the arteries open and controls the lumen diameter by contracting and relaxing

66
Q

What are capillairy walls made of?

A

single-celled and flattened (squamous) layer of endothelial cells

67
Q

Why are capillaries thin?

A

for exchange - short diffusion pathway

68
Q

Why do capillaries have a narrow lumen?

A

can squeeze rbc against the endothelium to improve the transfer of O2 - shortens diffusion distance

69
Q

why is the vein lumen wide?

A

allows max blood flow and get deoxy blood back to the heart as fast as possible

70
Q

What is the relationship between the total cross-sectional area and rate of flow?

A

indirectly proportional - as tot cross-sec increases, the rate of flow decreases

71
Q

What is the decrisption of the total cross sectional area on the blood vessels graph?

A

it increases going away from the heart and is at its highest in the capillaires
decreases coming back towards the heart

72
Q

What is the decrisption of the rate of flow on the blood vessels graph?

A

it decreases aorta –> arterioles
lowest at capillaries - allows time for exchange
increases venules –> vena cava

73
Q

What is the decrisption of the blood pressure on the blood vessels graph?

A

it is highest in the aorta and arteries
fluctuates rhythmecally - due to pulse
falls continuesly as blood goes away from the heart
it never falls to 0 = the semi-lunar valves close

74
Q

What is the relationship of the total cross sectional area and the surface area?

A

the SA decreases, the tot cross sec increases

75
Q

What happens when friction increases inside the blood vessels?

A

the pressure falls and the flow rate slows

76
Q

Describe an arteries lumen

A

has a narrow diamter in relation to tot diameter therefore a high resistance to blood flow which maintains pressure

77
Q

Describe the arteries elastic tissue

A

thick elastic tissue layer in walls to allow walls to expand with each pulse of blood and then return to original shape - called elastic recoil
this evens out blood flow and maintains a high pressure

78
Q

Describe the arteries muscle layer

A

thick smooth elastic layer in walls which can contract /relax altering blood pressure

79
Q

Which arteries have valves?

A

aorta and pulmonary artery

80
Q

Describe a veins lumen

A

wide lumen in relation to diameter therefore less resistance to blood flow which helps blood return to the heart

81
Q

describe veins muscle layer

A

thin smooth muscle layer in walls. less muscle to contract so will not narrow lumen to resist blood flow

82
Q

describe veins elastic layer

A

thin elastic tissue layer in walls. as there is no need to expand with each pulse of blood therefore no need for elastic recoil - there isnt a high pressure

83
Q

Why do the veins thin walls aid blood flow?

A

they can be flattened easily by muscles forcing blood to return to the heart

84
Q

What valves do veins have?

A

semi-lunar valves to prevent backflow of blood caused by low blood pressure

85
Q

describe a capillaries lumen

A

narrow lumen casues and increase in tot cross sec so more surface is in contact with blood, causing greater friction between blood and capillary wall
results in loss of blood pressure

86
Q

Why do capillaries have pores?

A

they have fenerstrations - making it permeable so small molecules can filter out

87
Q

What does the tough fibrous outer layer do in blood vessels?

A

resists pressure changes from both within and outside

88
Q

What does the thin inner lining (endothelium) do in blood vessels?

A

smooth to reduce friction and thin to allow diffusion

89
Q

How do capillaries have a large SA for exchange?

A

dense network

90
Q

How do capillaires have a short diffusion pathway for exchange?

A

single layer of endothlial cells
flattened endothelial cells
rbc in contact with walls
narrow lumen causes rbc to pass in single file

91
Q

How do capillaries allow formation of tissue fluid?

A

fenerstrations between endothelial cells

92
Q

What is venous return?

A

blood returning to the heart by the vena cava

93
Q

How is the blood returned to the heart by the suction effect?

A

during atria diastole there is a low pressure in the atria so the blood moves towards the heart down a pressure gradient

94
Q

How is blood returned to the heart by the skeletal muscles?

A

When the skeletal muscles contract it increases the pressure in the veins - forces blood through the valves and blood to return to the heart
the valves then close again to prevent back flow

95
Q

How is blood pressure maintained in the arteries during systole?

A

the structure:
the elastic fibres can expand and enable blood flow to withstand pressures during systole

96
Q

How is blood pressure maintained in the arteries during diastole?

A

when pressure falls - the elastic fibres recoil to maintain high pressures

97
Q

What are the blood’s functions?

A

specialised transport medium
the immune system
thermoregulation
maintains pH of body fluids

98
Q

What are the two main things blood is made of?

A

45% cells
55% plasma

99
Q

What is in the cells part of the blood?

A

erythrocytes (RBC) for transport O2
Leukocytes (WBC) for immune system
thrombocytes (platelets) for clotting

100
Q

What is in the blood plasma?

A

water (92%)
plasma proteins (enzymes, antibodies)
ions (K+, Na+, Cl-, Ca2+)
nutrients (glucose, amino acids)
waste (urea)
hormones
gases

101
Q

Why does a erythrocyte have a flattened biconcave shape?

A

large SA:VOL for increased efficiency of O2 exchange

102
Q

Why don’t erythrocytes have a nucleus or organelles?

A

more room for heam therefore more O2 can be transported

103
Q

Why is the diamter of a erythrocyte larger than a capillaries diameter?

A

RBC has to squeeze through capillary - short diff pathway
slows down RBC for more time for exchange

104
Q

How is the high hydrostatic pressure created at the arterial end of the capillary?

A

ventricular systole and elastic recoil in arteries maintains pressure
vol decreases arteriole -> capillary

105
Q

How is tissue fluid formed?

A

high hydrostatic pressure at arterial end of the capillary
ultrafiltration of small molecules - through fenerstrations in the capillaries
large molecules and some water stays in the capillary

106
Q

What is tissue fluid?

A

the fluid containing water, glucose, amino acids, fatty acids, ions and O2 which bathes the tissues

107
Q

Why dont blood cells or plasma proteins leave the capillary during untrafiltration?

A

too large to fit through capillary fenertrations

108
Q

What happens as blood flows through the capillary after forming tissue fluid?

A

there is a decrease in water potential as there is a high conc of plasma proteins in the blood
water is pulled back into the capillary ar the venous end

109
Q

How do cells take up lipid soluble molecules and gases?

A

simple diffusion

110
Q

How do cells take up glucose?

A

active transport

111
Q

How is tissue fluid reabsorbed into the blood?

A

at the venous end of the capillary
large molecules remained in the capillary create a lower water potential - water re-enters by osmosis
theres a lower hydrostatic pressure as the liquid was lost - dissolved waste molecules enter

112
Q

Why isnt all tissue fluid reabsorbed?

A

an equilibrium will be reached

113
Q

What happens to excess tissue fluid?

A

called lymph
drained into the lymphatic system and is eventually drained back into the bloodstream near the heart

114
Q

How are the contents of the lymphatic system moved?

A

contraction of muscles - squeezes lymph vessels - valves ensure it moves towards the heart

115
Q

What is the structure of a lymph vessel?

A

single layer of overlapping epithelial cells
valves - ensures uni-directional flow
blind-ended - ensures uni-directional flow

116
Q

How does lymph return to the blood?

A

via the thoratic duct or the subclavian vein

117
Q

What are the vessels connecting the heart and liver called?

A

the heptic vein and artery

118
Q

What is a risk factor?

A

something that increases the likelihood of developing a disease

119
Q

What are the forces opposing the high hydrostatic pressure of tissue fluid leaving the blood?

A

high hydrostatic pressure of tissue fluid outside of the capillaries prevents the outward movment of the liquid
lower water potential of the blood - pulls water back into the capillaries

120
Q

What is lymph made of?

A

tissue fluid
fatty substances
lymphocytes

121
Q

What are the 4 subunits haemoglobin is made of?

A

x2 alpha and x2 beta subunits

122
Q

What is 1 subunit made of in haemoglobin?

A

a polypeptide chain and a Fe2+ ion (haem group)

123
Q

Where does O2 associate in haemoglobin?

A

to the haem group

124
Q

What is oxyhaemoglobin?

A

a fully saturated haemoglobin
HbO8 - 4O2 per haemoglobin

125
Q

How are there different haemoglobins?

A

have different shapes in different species due to the different amino acid sequences

126
Q

When does haemoglobin’s affinity for O2 change?

A

under different conditions - it will chnage its shape in the presence of certain substances

127
Q

Where does oxygen associate to hb?

A

in the alveoli - high O2 conc in the tissue - high partial pressure of O2 = high affinity of O2 - O2 binds tightly

128
Q

Where does O2 dissociate from hb?

A

respiring tissues - low O2 conc in tissue as it is used in aerobic resp = low pO2 = low affinity for O2 = dissociation

129
Q

What are the steps of co-operative binding?

A

it is difficult for the first O2 to bind as it is difficult to reach the haem group - polypeptide chains are packed tightly at low pO2
when the 1st O2 binds, the hb changes shape + opens up polypeptide chains
makes it easier for next O2 to bind
the last O2 is the easiest to bind but a large pO2 is needed for all hb to be saturated

130
Q

What does the top of the O2 dissociation curve show?

A

high pO2 - in the alveoli
high levels of O2
high % saturation of O2 - high affinity for O2 - can readily dissociate

131
Q

What does the middle of the O2 dissociation graph show?

A

smll chnage in pO2 = large change in % saturation:

a small increase in resp rate = small decreases in pO2 of blood
causes a large decrease in % saturation
so more O2 is supplied to the tissues so the rate of resp can be maintained

132
Q

What does the bottom of the O2 dissociation curve show?

A

low pO2 - resp muscle cells
low % saturation = low affinity for O2

133
Q

What is oxyhaemoglobin?

A

all haem groups are bound to O2 - it is saturated

134
Q

What does a left shift of the O2 dissociation graph mean in terms of affinity for O2?

A

increases affinity for O2
in a low O2 environment

135
Q

What does a right shift of the O2 dissociation graph mean in terms of affinity for O2?

A

decreased affinity for O2
increase pCO2
decreased pH

136
Q

What causes the Bohr effect (right shift)?

A

high pCO2 due to activity - anerobic resp in muscle tissues
increased pCO2 in blood
lowers the pH of the blood
reduces affinity of hb for O2
more O2 being unloaded at the same pO2
more O2 being released to the tissues overall
tissues can maintain increased rate of aerobi resp

137
Q

What causes the left shift dissociation curve (llama and foetus)?

A

low pO2 conditions (mountains/ underground/ in womb)
hb has adapted high affinity for O2
acheives high % saturation at low pO2
so O2 can be unloaded to tissues at low PO2
maintains aerobic resp in low pO2 environment

138
Q

What is the advantage of organisms living in low O2 environments having adapted haemoglobin?

A

it can still associate with O2 with little O2 in the air and acheive high % saturation and unload O2 to resp tissues

139
Q

Describe the structure of haemoglobin

A

a globular protein made up of 2 alpha chains and 2 beta chains
each chain folds and contains a haem group which contains iron ions where oxygen binds

140
Q

What is partial pressure?

A

the pressure a gas exerts in a mixture of gases

141
Q

Explain the Oxygen dissociation graph in terms of how an O2 molecule binds to haemoglobin

A
  1. initially the curve is shallow = it is hard for the first molecules to bind
  2. steep increases = hb changes shape and easier to bind (positive cooperativity)
  3. gradient flattens = the liklihood that the 4th O2 binds is low
142
Q

Explain the effect of CO2 concentration on the dissociation curve

A

increasing CO2 decreases haemoglobin’s affinity for O2
increasing CO2 = increases acidity = changes shape of haemoglobin protein = easier for O2 to be released

Biology A level (27 decks)

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