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Biology > 3.1.2 - Transport in animals > Flashcards

3.1.2 - Transport in animals Flashcards

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1
Q

Give 4 reasons why specialist transport systems are needed

A
  • Metabolic demands of most animals is high
  • SA:V decreases as animal size increases so diffusion distances increase whilst SA available becomes relatively smaller
  • Molecules need to be moved large distances
  • Waste products of metabolism need to be removed from cells and transported to excretory systems
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2
Q

As an organism gets larger what happens to the diffusion distance ?

A

It gets larger

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3
Q

Why does a greater level of activity in an organism increase demand for glucose and oxygen ?

A
  • More activity requires more energy
  • More energy requires more aerobic respiration
  • Which requires more reactants (oxygen and glucose)
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4
Q

Why does a greater volume of an organism mean a greater demand ?

A
  • Greater volume means greater number of cells
  • Each cell requires energy
  • So demand for energy/glucose/oxygen increases
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5
Q

Define mass flow

A

The movement of fluids down a pressure or concentration gradient, from high to low

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6
Q

Define circulatory system

A

The transport system of an organism

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7
Q

Define open circulatory system

A

A transport system with a heart but with few vessels to contain the transport medium

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8
Q

Define closed circulatory system

A

The transport medium is enclosed in vessels and does not come into contact with the cells of the body

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9
Q

Define haemolymph

A

The blood like fluid contained in insects

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10
Q

Define single circulatory system

A

A circulatory system where the blood flows through the heart once during a complete circuit of the body

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11
Q

Define double circulatory system

A

A circulatory system where the blood flows through the heart twice during a complete circuit of the body

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12
Q

Define pulmonary circulation

A

The part of the circulatory system which carries deoxygenated blood away from the right ventricle of the heart to the lungs and returns oxygenated blood to the left atrium

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13
Q

Define systemic circulation

A

The part of the circulatory system which carries oxygenated blood away from the heart to the body and returns deoxygenated blood back to the heart

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14
Q

Give examples of organisms with a single closed circulatory system

A
  • Fish

- Annelid worms

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15
Q

Give examples of organisms with a double closed circulatory system

A
  • Birds

- Most mammals

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16
Q

Give an example of an organism with an open circulatory system

A

Insects

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17
Q

Why are fish able to be highly active despite having a single closed circulatory system ?

A
  • The countercurrent exchange mechanism means they can take up a lot of O2 from water
  • Their body weight is supported by the water
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18
Q

Why are single closed circulatory systems not very efficient ?

A

Blood pressure drops considerably so blood flows slowly back to the heart

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19
Q

Why are double closed circulatory systems very efficient ?

A
  • Each circuit passes through only one capillary network this maintains relatively high blood pressure
  • So fast flow of blood back to the heart is maintained
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20
Q

What are the general features of circulatory systems ?

A
  • Fluid to transport dissolved gases, nutrients, and waste
  • A pumping mechanism to move fluid
  • Sometimes vessels to carry the fluid
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21
Q

How are open and closed circulatory systems different ?

A
  • Blood is enclosed in vessels in a closed system but not in an open system
  • In open systems, the fluid fills body cavities
  • An open system is less efficient
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22
Q

What is an advantage of having an open circulatory system ?

A

Less vulnerable to pressure

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23
Q

What is an advantage of closed circulatory systems ?

A

More efficient

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24
Q

What is a disadvantage of open circulatory systems ?

A

Requires low metabolic rate so does not work for larger animals

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25
Q

What is a disadvantage of closed circulatory systems?

A

Requires more energy

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26
Q

What is the disadvantage of single circulatory systems ?

A

They are less efficient

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27
Q

What are the differences between single and double circulatory systems ?

A
  • Blood goes through the heart once in one complete circuit in a single system and twice in a double system
  • Single system has two sets of capillaries while double system has one set of capillaries
  • Double system maintains a higher pressure than a single system
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28
Q

What is plasma?

A

Liquid component of blood

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29
Q

What is the function of plasma?

A

Transports dissolved substances

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30
Q

What does plasma transport ?

A

e.g glucose, amino acids, mineral ions, hormones, albumin and fibrinogens

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31
Q

Why is albumin important ?

A

It helps to maintain oncotic pressure

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32
Q

Why are fibrinogens important ?

A

They are involved in blood clotting

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33
Q

What are platelets?

A

Small fragments of cells

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34
Q

Which is the function of platelets?

A

Start the process of blood clotting

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35
Q

What triggers blood clotting?

A
  • A rough surface

- Exposure to air

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36
Q

What are the functions of blood as a whole?

A
  • Transport of oxygen and carbon dioxide to and from respiring cells
  • Transport hormones
  • Transport nitrogenous waste products from cells to excretory organs
  • Transporting cells and antibodies involved in the immune response
  • Helps to maintain steady body temperature
  • Acts as a buffer to minimise pH change
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37
Q

What are the 3 layers of arteries called?

A
  • Tunica intima
  • Tunica media
  • Tunica externa
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38
Q

What makes up the tunica intima of the arteries?

A

Squamous epithelial cells

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39
Q

What makes up the tunica media of the arteries?

A

Smooth muscle and elastic fibres

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40
Q

What makes up the tunica externa of the arteries?

A

Collagen

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41
Q

Why is the tunica intmia of arteries smooth?

A

So blood flows over it easily

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42
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

They allow for elastic recoil

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43
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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44
Q

What are the functions of the arteries?

A

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

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45
Q

What is blood flow into arteries like?

A
  • High pressure
  • Pulsatile
  • Fast
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46
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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47
Q

What does contact of blood with artery walls cause?

A
  • Friction
  • Slows blood down
  • Evens out pulsatile flow
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48
Q

What is the function of the arterioles?

A

Regulate the flow of blood into the capillaries

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49
Q

Do arterioles have a higher proportion of smooth muscle than arteries?

A

Yes

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50
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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51
Q

Why is blood slower in the arterioles?

A

Due to friction with the vessel walls

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52
Q

How does the slightly wider lumen in arterioles affect pressure?

A

Reduces it slightly

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53
Q

What is the function of the smooth muscle?

A

It is neurally stimulated to cause vasoconstriction or vasodilation which controls the flow of blood into capillaries

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54
Q

What is the function of capillaries?

A

To exchange substances between the blood and tissues

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55
Q

What is the advantage of capillaries being one cell thick?

A

Gives a short diffusion pathway

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56
Q

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

A

Gives a longer time for the exchange of substances

57
Q

Why is the blood pressure low through the capillaries?

A
  • The pressure is spread across many blood vessels

- Prevents them from bursting

58
Q

What is blood flow like through capillaries?

A

Smooth, low pressure, slow

59
Q

What is the function of venules?

A

To link capillaries to veins

60
Q

What are the walls of venules mostly made of?

A

Collagen

61
Q

Why do venules have a thin tunica media?

A

They flow at low pressures so don’t require muscle or elastic fibres as they don’t have to withstand high pressures

62
Q

Why do veins have a wide lumen?

A

To accommodate the large volume of blood carried

63
Q

What is the blood flow through veins like?

A

Very slow, low pressure and smooth

64
Q

Why are valves present in veins?

A

They prevent back flow

65
Q

What 3 mechanisms aid blood flow back to the heart?

A
  • Skeletal muscles contract/relax and pushblood through veins as they lie near the surface
  • Valves prevent back flow
  • Breathing mechanism causes negative pressure in the thorax so pulls blood towards the heart
66
Q

What is tissue fluid?

A

A liquid produced from the circulatory system which contains dissolved nutrients

67
Q

What is the function of tissue fluid?

A
  • Transports substances to the tissues and returns waste products of the cells back to the circulatory system
  • Allows the cells to take up the products needed
68
Q

Give 3 examples of substances found dissolved in tissue fluid

A
  • Glucose
  • Amino Acids
  • Oxygen
  • Carbon Dioxide
69
Q

What happens to excess tissue fluid?

A
  • Drains into lymph vessels

- Some tissue fluid returns to capillaries

70
Q

What is lymph ?

A

Tissue fluid that is collected in the lymph system

71
Q

What is the lymphatic system?

A

System that contains drainage vessels for lymphatic fluids

72
Q

What are the functions of lymph nodes?

A

Involved in immune response and contain lymphocytes

73
Q

What is the function of pores in capillaries?

A
  • Allows tissue fluid to leave capillaries

- Do not allow blood cells or large proteins out of the blood

74
Q

Why does tissue fluid move in and out of capillaries?

A

Due to opposing blood pressures

75
Q

What is hydrostatic pressure?

A

The pressure created by water in an enclosed system

76
Q

What is oncotic pressure?

A

The pressure caused by water moving into the blood by osmosis as a result of plasma proteins

77
Q

Why does hydrostatic pressure fall as blood and tissue fluid move through the capillaries?

A

Due to increased distance from the heart and branching of the arterioles into many capillaries

78
Q

Why does oncotic pressure stay the same throughout the capillaries?

A

The plasma proteins in the blood which generate the pressure are too large to fit through capillary pores

79
Q

In what direction does tissue fluid move at the arteriole end of the capillary?

A

Out of the capillary

80
Q

Why is tissue fluid forced out of the capillary at the arteriole end ?

A

The oncotic pressure is greater than the hydrostatic pressure so tissue fluid is drawn into the blood

81
Q

Outline the movement of blood through the heart

A
  • vena cava into right atrium
  • through tricuspid AV valve
  • right ventricle
  • semi-lunar valves
  • pulmonary artery
  • lungs
  • pulmonary veins
  • left atrium
  • bicuspid AV valve
  • left ventricle
  • semi-lunar valve
  • aorta
82
Q

What is the heart made out of ?

A

Cardiac muscle

83
Q

How is cardiac muscle described?

A

Myogenic

84
Q

What does myogenic mean ?

A

Heart muscle has its own intrinsic rhythm

85
Q

What is the difference between cardiac muscle and skeletal muscle ?

A

Cardiac muscle does not get fatigued and need to rest

86
Q

Why is the heart described as a double pump ?

A
  • Blood is pumped through the heart twice
  • First time deoxygenated blood is pumped to lungs
  • Second time oxygenated blood is pumped to the body
87
Q

What is the function of the coronary arteries ?

A

Supply the heart muscle with oxygen and glucose in order to keep it contracting and relaxing all the time

88
Q

What is the function of pericardial membranes ?

A

They help to prevent the heart from swelling with blood, due to increased pressures

89
Q

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

A

Yes

90
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 the pulmonary circulation
91
Q

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

A
  • The left side must provide sufficient force to overcome the resistance of the aorta and arterial systems of the whole body
  • Left side must move the blood under pressure to all extremities of the body
92
Q

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

A

It increases

93
Q

As ventricular pressure increases, what happens to aortic pressure and why ?

A
  • It increases

- Blood flows into the aorta at high pressure

94
Q

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

A

Region of the heart that initiates a wave of excitation that triggers the contraction of the heart

95
Q

What is the sino-atrial node also known as?

A

The pacemaker region

96
Q

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

A

It stimulates the ventricles to contract after a slight delay

97
Q

Why does the atrio-ventricular node impose a slight delay?

A

To ensure atrial contraction is complete first before contracting blood out after

98
Q

What is the bundle of His?

A
  • Conducting tissue made of purkyne fibres that passes through the septum
99
Q

What are Purkyne fibres?

A

Tissue that conducts the wave of excitation to the bottom (apex) of the heart

100
Q

What is the function of the septum?

A

Prevents the mixing of oxygenated and deoxygenated blood

101
Q

What is the function of the valves in the heart?

A

Prevents back flow of the blood and so ensures efficient movement of blood

102
Q

What is the function of tendinous cords ?

A

They help to prevent prolapse of the valves

103
Q

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

A
  • Divides into smaller vessels
  • Vessels have larger total cross sectional area
  • Loss of plasma from the capillaries
104
Q

Outline the movement of electrical signals through the heart

A
  • Wave of depolarisation begins at the SAN which causes atria to contract
  • Wave of depolarisation travels to AVN
  • AVN imposes slight delay before stimulating the bundle of His
  • AVN stimulates the bundle of His
  • Bundle of His splits into two branches and conducts the wave of excitation to the apex
  • At the apex, the purkyne fibres spread out through ventricular walls
  • Spread of excitation triggers the contraction of ventricles
105
Q

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

A

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

106
Q

Why is it important that the AVN imposes a slight delay?

A
  • Ensures the atria contract before the ventricles

- All atrial blood empties into ventricles before the ventricles contract

107
Q

Why do ventricles contract from the apex up?

A
  • Blood needs to be moved upwards

- It ensures that there is complete emptying of ventricles

108
Q

What is the effect on the heart of the sympathetic nerve releasing noradrenaline?

A

Heart rate increases

109
Q

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

A

Heart rate decreases

110
Q

What does ECG stand for?

A

Electrocardiogram

111
Q

What does an ECG show?

A

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

112
Q

What is the x axis on an ECG?

A

Time

113
Q

What is the y axis on an ECG?

A

Electrical potential (mV)

114
Q

What does the P wave on an ECG show?

A

Depolarisation of atria in response to SAN triggering the atria to contract

115
Q

What does the QRS wave on an ECG show?

A
  • Ventricular systole
  • Wave of depolarisation in ventricle walls
  • Ventricles contract
  • AV valve closes
116
Q

What does the T wave on an ECG show?

A

Ventricles relax

117
Q

How can heart rate be measured using an ECG?

A

Heart rate is the time between the peaks (R)

118
Q

What is the cardiac cycle ?

A

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

119
Q

What occurs during atrial diastole?

A
  • Both atria and ventricles are relaxed
  • Blood enters the right atrium via the vena cava and the left atrium via the pulmonary vein
  • Atria fill with blood
  • AV valves are closed
  • Pressure in atria increases as they fill with blood
  • Semi-lunar valves are closed
120
Q

What occurs during atrial systole?

A
  • Atria contract
  • Contract almost simultaneously
  • Atrial pressure higher than ventricular pressure so AV valves open
  • The semi-lunar valves are still closed
121
Q

What occurs during ventricular systole?

A
  • Ventricles fill with blood and contract
  • AV valves close so blood isn’t forced back into the atria
  • Semilunar valves open with forces blood into the aorta/pulmonary artery
122
Q

What occurs during ventricular diastole?

A
  • pressure in the aorta and pulmonary artery increases
  • ventricles relaxed
  • Semi-lunar valves close to prevent backflow
123
Q

What causes the heart sounds?

A

Blood hitting the heart valves

124
Q

What causes the ‘lub’ sound?

A

Blood hitting AV valves as ventricles contract

125
Q

What causes the ‘dub’ sound ?

A

Backflow of blood hitting the semilunar valves

126
Q

When does the ‘lub’ sound happen?

A

During ventricular systole

127
Q

When does the ‘dub’ sound happen ?

A

During ventricular diastole

128
Q

What happens when ventricular pressure is greater than atrial pressure?

A

AV valve closes as systole is entered

129
Q

Why do the semilunar valves open?

A

Because pressure in the ventricles is higher than the pressure in the aorta

130
Q

Why do the semilunar valves close?

A

The pressure in the aorta is greater than in the ventricles

131
Q

Why do AV valves open ?

A

Atrial pressure is greater than ventricular pressure

132
Q

Why does ventricular pressure increase after the closing of the AV valve?

A

Due to the thicker ventricle wall

133
Q

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

A
  • Volume decreases

- Pressure increases

134
Q

What is arrhythmia?

A

An abnormal rhythm of the heart

135
Q

What is bradycardia?

A

The heart beats more slowly than normal rhythm, less than 60bpm

136
Q

What is Tachycardia?

A

A fast heart rate (over 100bpm)

137
Q

What is ectopic heartbeart?

A

Extra heartbeats that are out of the normal rhythm

138
Q

What is atrial fibrilation?

A

Abnormal rhythm of the heart when the atria beat very fast and incompletely

139
Q

How are ECGs measured?

A
  • Electrodes stuck on skin
  • Measure electrical differences in the skin
  • Signal fed into machine which produces an ECG

Biology (30 decks)

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