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AQA A level Biology > 3.4.1 Mass transport in animals > Flashcards

3.4.1 Mass transport in animals Flashcards

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1
Q

What type of organisms can rely on diffusion alone

A

Small organisms

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2
Q

Why do large organisms have to develop a transport system

A

Due to increasing size, their surface area to volume ratio has decreased to the point where the demand of the organism cannot be met by the body surface alone

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3
Q

What is a transport system required to do

A

To take materials from cells to exchange surfaces and from exchange surfaces to cells

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4
Q

What type of circulatory system do mammals have

A

A closed, double circulatory system

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5
Q

What does the term ‘closed’ mean when describing the circulatory system

A

All the blood vessels are connected in a circuit, meaning that the blood always remains in those blood vessels as long as there is no damage to the blood vessels

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6
Q

What does the term ‘double’ mean when describing the circulatory system

A

The blood passes through the heart twice in each circuit.

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7
Q

In mammals, where do the circuits deliver the blood to

A
  1. Delivers blood to the lungs
  2. Deliver blood to the rest of the body
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8
Q

Why do mammals require a double circulatory system

A

To manage the pressure of the blood

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9
Q

Why does the blood need to return to the heart after going to the lungs

A

Because when blood is passed through the heart, its pressure is reduced

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10
Q

Why does the blood flow through the lungs at a lower pressure (2 reasons)

A
  • To prevent damage to the capillaries surrounding the alveoli
  • Lower pressure = moving more slowly, enabling more time for gas exchange
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11
Q

What is the name of the circuit between the heart and the lungs

A

Pulmonary circulation

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12
Q

Why does the blood need be pumped again at the heart in order to get a higher pressure

A

To ensure that the blood reaches all the respiring cells in the body

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13
Q

In a circulatory system, what are the 3 key features

A
  • Transport fluid
  • Pump
  • Series of tubes
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14
Q

In mammals, what is their pump

A

Heart

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15
Q

In mammals, what is their transport fluid

A

Blood plasma

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16
Q

In mammals, what is their series of tubes

A

Blood vessels

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17
Q

What is the name of the circuit between the heart and the rest of the body called

A

The systemic circulation

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18
Q

In pulmonary circulation, what type of blood is carried from the heart to the lungs

A

Deoxygenated

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19
Q

In pulmonary circulation, what type of blood is carried from the lungs to the heart

A

Oxygenated

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20
Q

In pulmonary circulation what vessel carries blood from the heart to the lungs

A

Pulmonary artery

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21
Q

In pulmonary circulation, what vessel carries blood from the lungs to the heart

A

Pulmonary vein

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22
Q

In systemic circulation, what type of blood is transported from the heart to the rest of the blood

A

Oxygenated

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23
Q

In systemic circulation, what type of blood is transported from the rest of the body to the heart

A

Deoxygenated

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24
Q

In systemic circulation, what vessel carries blood from the heart to the rest of the body

A

Aorta

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25
Q

In systemic circulation, what vessel carries blood from the rest of the body back to the heart

A

Vena cava

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26
Q

Where does the coronary arteries carry blood to

A

Supply the heart, the cardiac muscle, with oxygenated blood

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27
Q

What are the 4 major blood vessels that enter/ exit the heart

A
  • Veins - Vena cava, Pulmonary vein
  • Arteries- Aorta, Pulmonary artery
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28
Q

What are the 2 blood vessels connected to the lungs

A
  • Pulmonary artery
  • Pulmonary vein
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29
Q

What are the 2 blood vessels connected to the kidneys

A
  • Renal artery
  • Renal vein
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30
Q

What type of muscle is the heart made of

A

Cardiac muscle

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31
Q

What does the word ‘myogenic’ mean when describing the heart

A

Meaning that the muscle can contract or relax without any input from nervous system or hormones

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32
Q

What are the 2 unique properties of the cardiac muscle

A
  • It myogenic (it can contract and relax without stimulation)
  • It never fatigues, as long as it has a supply of oxygen
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33
Q

Where do the coronary arteries branch off from

A

The aorta

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34
Q

What is myocardial infarction

A

A heart attack

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35
Q

What causes a heart attack

A

Blockages in the coronary arteries- since oxygenated blood is not being supplied to the cardiac muscle so they can not respire

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36
Q

What are the 4 chambers in the heart called

A
  • Left atrium
  • Right atrium
  • Left ventricle
  • Right ventricle
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37
Q

Are the walls of the atria or the ventricle thicker

A

The ventricles have thicker muscular walls

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38
Q

Why are the muscular walls of the atria thinner than the muscular walls of the ventricles

A

As they don’t need to contract as hard as they aren’t pumping blood far (only to the ventricles)

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39
Q

Why does the atria have elastic walls

A

To stretch when the blood enters

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40
Q

Why do ventricles have thicker muscular walls compared to atria

A

To contract with greater force to push to blood out at higher pressure

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41
Q

Why do the ventricles need to create a higher blood pressure when contracting than atria

A

To enable blood to flow a longer distance (R ventricle to the lungs, L ventricle to the rest of the body)

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42
Q

Which ventricle wall is thinner the left or right

A

The right ventricle wall is thinner

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43
Q

Why does the right ventricle have thinner walls

A

Because it pumps blood to the lungs, and we don’t want too high of a pressure in the lungs (could damage capillaries, and it needs to be slow for gas exchange)

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44
Q

Why does the left ventricle have a thicker muscular wall

A

It needs to contract with the highest force to pump the blood out at the highest pressure. The blood is going to the rest of the body

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45
Q

What type of blood vessels bring blood into the heart

A

Veins

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46
Q

What type of blood vessels take blood away from the heart

A

Arteries

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47
Q

What are the 2 veins into the heart

A
  • Vena cava
  • Pulmonary vein
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48
Q

What type of blood does the vena cava carry

A

Deoxygenated blood

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49
Q

Where does the vena cava carry blood from and to in the heart

A

From the blood
Into the right atrium

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50
Q

What type of blood does the pulmonary vein carry

A

Oxygenated blood

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51
Q

Where does the pulmonary vein carry blood from and to in the heart

A

From the lungs
Into the left atrium

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52
Q

What are the 2 arteries connected to the heart

A
  • Pulmonary artery
  • Aorta
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53
Q

What type of blood does the pulmonary artery carry

A

Deoxygenated blood

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54
Q

Where does the pulmonary artery carry blood from and to

A

From the right ventricle
To the lungs (to become oxygenated)

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55
Q

What type of blood does the aorta carry

A

Oxygenated blood

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56
Q

Where does the aorta carry blood to and from

A

From the left ventricle
To the rest of the body

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57
Q

What are the 2 types of valves in the heart

A
  • Semi- lunar valves
  • Atrioventricular valves
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58
Q

Where are the semi-lunar valves located

A

Between ventricle and artery

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59
Q

Where are the atrioventricular valves found

A

Between the atrium and the ventricles

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60
Q

What is another name for the atrioventricular valves on the right side of the heart

A

Tricuspid valve

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61
Q

What is another name for the atrioventricular valves on the left side of the heart

A
  • Bicuspid valves
  • Mitral valve
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62
Q

How many flaps / membranes are on the left atrioventricular valve

A

2

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63
Q

How many flaps / membranes are on the right atrioventricular valve

A

3

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64
Q

What is the role of valves

A

To prevent back flow of blood

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65
Q

When do valves open

A

When there is a higher pressure from behind

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66
Q

When do valves close

A

When there is a higher pressure from in front

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67
Q

What is the septum (in the heart)

A

A piece of cardiac muscle that runs all the way down the middle, separating the left and right side of the heart, separating the oxygenated blood from the deoxygenated blood

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68
Q

Why is separating the oxygenated and deoxygenated blood (the septum) important

A

The oxygenated blood isn’t being diluted by the deoxygenated blood. There is a very high concentration of oxygen within the oxygenated blood, this maintains concentration gradient which enables diffusion at respiring cells

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69
Q

What are the 3 stages of the cardiac cycle

A
  • Diastole
  • Atrial systole
  • Ventricular systole
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70
Q

What does diastole mean

A

Relaxing

71
Q

What does systole mean

A

Contracting

72
Q

What is the atria and the ventricles are doing during diastole

A

Both are relaxing

73
Q

Why does the blood flow into the atria during diastole

A

Since the muscles are relaxing which increases the volume therefore decreasing the pressure and blood always flows down a pressure gradient

74
Q

What does the blood flowing into the atria do the the pressure in the atria

A

It increases the pressure

75
Q

What happens to the atria muscular walls and the ventricle muscular walls during atria systole

A
  • Atria contract
  • Ventricle are still in diastole
76
Q

What does the contracting of the atria muscular walls do to the pressure in the atria

A

It increases it further (it increased when blood flowed into it) as the volume decreases

77
Q

What does the pressure increase in the atria during atrial systole do to the atrioventricular valves

A

They’re forced open so blood can flow from the atrium into the ventricle

78
Q

What happens to the atria and ventricles during ventricular systole

A

Atria- muscular walls relax
Ventricle- muscular walls contract

79
Q

What does the contracting of the ventricular muscular walls do to the volume and pressure in the ventricles

A

Volume- decreases
Pressure- increases beyond that of the atria

80
Q

What happens to the atrioventricular valves during ventricular systole

A

They close

81
Q

What happens to the semi-lunar valves during ventricular systole

A

They open- the blood is pushed out of the ventricles into the arteries

82
Q

What is the cardiac cycles

A

The sequence of events that happen in a single heart beat

83
Q

What is cardiac output

A

The volume of the blood which leaves one ventricle in 1 minute

84
Q

What is the calculation for cardiac output

A

Cardiac output= stroke volume x heart rate

85
Q

What is meant by heart rate

A

Beats of the heart per minute

86
Q

What is meant by stroke volume

A

Volume of blood that leaves the heart each beat

87
Q

When do the atrioventricular valves open

A

When the pressure is higher in the atria compared to the ventricles

88
Q

When do the atrioventricular valves close

A

When the pressure is higher in the ventricles compared to the atria

89
Q

When do the semi- lunar valves open

A

When the pressure is higher in the ventricles compared to the arteries (pulmonary artery and aorta)

90
Q

When do the semi- lunar valves close

A

When the pressure is higher in the arteries compared to the ventricles

91
Q

What are the 5 types of blood vessels

A
  • Arteries
  • Arterioles
  • Capillaries
  • Venules
  • Veins
92
Q

What blood vessel is the site of exchange

A

Capillary

93
Q

What happens to the total cross-sectional area as the blood flows away from the heart to the capillaries, and why

A

It increases since the vessels divide and divide so there are more vessels

94
Q

Why does the pressure fall as the blood vessels get smaller

A

Because the friction increases

95
Q

What does the lower pressure in smaller vessels do to the rate of blood flow

A

It slows it

96
Q

Through which blood vessel does blood move through the slowest

A

The capillaries

97
Q

What is the benefit of blood flowing through the capillaries slowly

A

Allow more time for exchange

98
Q

In which vessel in the blood pressure the highest

A

The aorta

99
Q

Why doesn’t blood pressure fall to zero in the aorta

A

Because the semi-lunar valves close during ventricular diastole so the ventricle volume increases so the pressure decreases but since the valve is closed the pressure remains high in the aorta

100
Q

What is the lumen of the arteries/ arterioles like

A

Narrow in relation to total diameter, therefore HIGH RESISTANCE to blood flow which maintains blood pressure

101
Q

What are the walls of arteries/ arterioles like

A
  • THICK smooth muscle layer in walls which contract/ relax therefore altering the blood pressure
  • THICK elastic tissue layer which expands with each pulse of blood and recoils- maintaining HIGH PRESSURE
102
Q

What are the only arteries which valves

A
  • Aorta
  • Pulmonary artery
103
Q

What is the lumen of veins/ venules like

A

WIDE lumen in relation to diameter, therefore LESS RESISTANCE to blood flow which helps blood return to the heart

104
Q

What are the walls of veins/ venules like

A
  • THIN smooth muscle layer- less muscle to contract so will not narrow lumen to resist blood flow
  • THIN elastic tissue layer- as there is no need for expansion during each pulse of blood so no need for recoil
105
Q

What valves do veins/ venules have

A

Semi-lunar valves that prevent the back flow of blood

106
Q

What is the lumen of capillaries like

A
  • NARROW lumen causes increase in total cross-sectional area, so more surface is in contact with blood, causing GREATER FRICTION between blood and capillary wall- causing a loss of blood pressure
107
Q

What does the low blood pressure in the capillaries do to the flow of blood, and why is this good

A

It slows the flows, allowing more time for exchange

108
Q

What are the walls of the capillaries like

A
  • Made from SINGLE and FLATTENED layer of ENDOTHELIAL cells - which reduces diffusion pathway
  • Has small pores (fenestrations) making it permeable so small molecules can filter out
109
Q

Do capillaries contain valves

A

No

110
Q

How do arteries WITHSTAND high pressure

A

They expand since they contain elastic fibres

111
Q

How do arteries MAINTAIN high pressure

A

They recoil using their elastic fibres

112
Q

What type of muscles contract and squeeze the vein

A

Skeletal muscle

113
Q

How does the contraction of skeletal muscles aid venous return

A
  • They bulge when they contract which squeezes the veins
  • This decreases the volume of the veins, which increases the pressure of the vein
  • This causes the blood to be forced through the valves in front of the point of contraction and the valve behind to point of contraction to close.
  • Ensuring an unidirectional flow of blood
114
Q

What 2 things create a suction effect during venous return

A
  • Atria diastole- the pressure in atria is lower than the blood pressure- blood moves down a pressure gradient
  • Inhaling- the pressure of thoracic cavity decreases and the volume increases, so blood is sucked back to the heart, that is located in the thoracic cavity
115
Q

What are the 4 main functions of blood

A
  • Transport fluid
  • Immunological (immune system)
  • Thermoregulation
  • Maintaining pH of body tissues
116
Q

What percentage of blood is made up of cells

A

about 45 %

117
Q

What % of blood is made up of plasma

A

About 55%

118
Q

What is the real name of RBC

A

Erythrocytes

119
Q

What is the role of erythrocytes

A

To transport oxygen

120
Q

What is the real name of WBC

A

Leukocytes

121
Q

What is the role of leukocytes

A

Immune system

122
Q

What is the name of the cells in blood that clot the blood

A

Thrombocytes

123
Q

What 7 things are in blood plasma

A
  • Water - 92 %
  • Plasma proteins
  • Ions (K+, Na+, Cl-, Ca2+)
  • Nutrients (glucose and amino acids)
  • Waste (urea)
  • Hormones
  • Gases (oxygen and carbon dioxide)
124
Q

What are the 4 features of a erythrocyte

A
  • Flattened, biconcave shape
  • No organelles
  • Diameter is greater than that of the walls of the capillary
  • High concentration of haemoglobin
125
Q

Why is a erythrocyte being flattened and have a biconcave shape beneficial

A

It increases the surface area to volume ratio which in turn increases the efficiency of oxygen exchange

126
Q

Why is it beneficial to a erythrocyte to have no organelles

A

Allows for maximum space for haemoglobin so for oxygen transport

127
Q

Why is the diameter of a RBC being greater than that of the walls of the capillaries a benefit

A

The RBC has to squeeze through which shortens the rate of flow allowing for more time for exchange

128
Q

Why is a high concentration of haemoglobin beneficial to erythrocytes

A

It transports oxygen so the more haemoglobin the more oxygen

129
Q

Is the hydrostatic pressure higher at the arterial end of the capillary or the venous end

A

Arterial end

129
Q

What is tissue fluid

A

Fluid that surrounds the cells of the body. Its composition is similar to that of blood plasma except that it lacks proteins. It supplies nutrients to the cells and removes waste products.

129
Q

What is the name of the process where tissue fluid is forced out of the capillary at the arterial end due to hydrostatic pressure

A

Ultrafiltration

129
Q

What pressure is created by the heart pumping

A

Hydrostatic pressure

129
Q

Capillaries contain pores, what is the scientific name for these pores

A

Fenestrations

129
Q

What is the name of the membrane that surrounds the capillaries and stops large molecules from passing

A

Basement membrane

130
Q

What 2 things remain in the capillary after ultrafiltration, and why are these left in there

A
  • Large plasma proteins
  • Blood cells
    Since the basement membrane acts as a barrier to larger molecules
131
Q

What happens to the water potential of the capillary as it flows from the arterial end to the venous end

A

The water potential decreases

132
Q

What happens to excess glucose in the tissue fluid

A

It returns to the blood

133
Q

What does the lymph system do

A

It drains excess tissue fluid and returns it to the blood

134
Q

How are the contents of the lymphatic system moved (2 things)

A
  • Hydrostatic pressure of the tissue fluid that has left the capillary
  • Contraction of body muscles that squeeze the lymph vessels- valves in the lymph vessel ensures that the fluid inside them moves away from the tissues in direction of the heart
135
Q

How do capillaries and lymph vessels differ

A

Capillaries have pores (fenestrations) whereas lymph vessels have overlapping walls which open under the weight of excess tissue fluid

136
Q

Why are lymph vessels blinded-ended

A

This ensures that they have a unidirectional flow of lymph (excess tissue fluid)

137
Q

What type is molecule is haemoglobin

A

A protein

138
Q

How many polypeptides chains make up a haemoglobin molecules

A

4

139
Q

What does haemoglobin transport

A

Oxygen

140
Q

What ion does a haem group contain

A

Fe 2+

141
Q

How many molecules of oxygen does each haem group combine with

A

One oxygen molecule

142
Q

What is the name of process given to the process by which haemoglobin binds with oxygen

A

Association or loading

143
Q

What is the name of the process by which haemoglobin releases oxygen

A

Dissociation or unloading

144
Q

What does affinity mean with respect to haemoglobin

A

The ability of haemoglobin to attract, or bind, to oxygen

145
Q

If haemoglobin has high affinity, what does this mean

A

Oxygen concentration is high- it will readily associate with oxygen and dissociate with it less easily

146
Q

If haemoglobin has low affinity, what does this mean

A

Oxygen concentration is low- means that it will readily dissociate and associate less easily

147
Q

To be good at transporting oxygen, what 2 characteristics must haemoglobin have

A
  • Load with oxygen at the gas exchange surface
  • Unload oxygen at respiring tissues
148
Q

How does haemoglobin change its affinity for oxygen

A

By changing its shape when in the presence of certain substances (like CO2)

149
Q

What is the name given to the increasing ease with which the 2nd, 3rd and 4th oxygen molecules combine with haemoglobin

A

Cooperative binding

150
Q

What is the saturation of haemoglobin with oxygen

A

When haemoglobin is holding the maximum amount of oxygen it can bind

151
Q

Describe the quaternary structure of haemoglobin

A

2 pairs of polypeptides (alpha and beta) link to form a spherical molecule. Each polypeptide has a game group that contains a Fe2+ ion

152
Q

Describe the shape of the oxyhaemoglobin dissociation curve

A

Sigmoid (s-shaped)

153
Q

When is the haemoglobin almost completely saturated

A

When oxygen is loaded in regions of high partial pressures of oxygen (e.g. in the alveoli)

154
Q

If haemoglobin’s affinity is lower, what is the partial pressure of oxygen like

A

Lower partial pressure of oxygen

155
Q

Where is oxygen unloaded (partial pressure and haemoglobins affinity)

A

In regions of lower partial pressure of oxygen, where haemoglobin has a lower affinity

156
Q

Why is there a low saturation of oxygen at low partial pressures of oxygen

A

Since the 1st oxygen molecules to bind to haemoglobin is very difficult

157
Q

Why is the 2nd and 3rd oxygen molecules easier to bind to the haemoglobin than the 1st oxygen molecule

A

Since haemoglobin is a protein so the shape changes.

158
Q

What is the Bohr effect

A

When a high concentration of carbon dioxide causes the oxyhaemoglobin curve to shift to the right

159
Q

When the oxyhaemoglobin curve shifts to the right, what happens to the haemoglobin’s affinity for oxygen

A

The affinity has decreased

160
Q

What does the shift to the right of the oxyhaemoglobin curve do, does it make Hb more readily load or unload, and why

A

Unload since the affinity for oxygen has decreases

161
Q

Why does the steepness of the curve, in the middle of the oxyhaemoglobin dissociation curve, help tissue function more efficiently

A

There is a small decrease in partial pressure of oxygen, results in a large decrease in % saturation so the oxygen goes to the tissue, so the tissues can aerobically respire which is more efficient than anaerobic respiration

162
Q

What does increased partial pressure of carbon dioxide do to the pH of blood and to the Hb affinity for oxygen

A

-Lowers the pH of the blood
-Lowers the affinity of Hb for oxygen

163
Q

At higher partial pressure of carbon dioxide is more or less oxygen unloaded at the same partial pressure of oxygen

A

More is unloaded, so overall more oxygen is released to the tissue

164
Q

What 2 types of haemoglobin (on the spec) that causes a shift to the left in the oxyhaemoglobin curve

A
  • Foetal
  • Llama
165
Q

How does foetal haemoglobin differ to adult haemoglobin

A

Foetal Hb has a higher affinity for oxygen, even at the same partial pressure of oxygen

166
Q

Why does Foetal Hb need to have a higher affinity for oxygen that adult Hb

A

Because they can’t inhale so their only source of oxygen is from the mothers Hb in the blood supply through the placenta

167
Q

How does llamas Hb differ from human Hb

A

Llamal Hb has a higher affinity for oxygen

168
Q

Why do llamas need a higher affinity for oxygen than humans

A

Since they live in an oxygen deficit environment

169
Q

Give 2 structural features of an aorta wall and explain how they are related to the function of an aorta (2 marks)

A
  • Smooth muscle withstands high blood pressure
  • Elastic tissue stretches and recoils to maintains blood pressure
  • Smooth endothelium reduces friction
  • Protein coat prevents artery wall splitting

AQA A level Biology (35 decks)

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