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Green > 3.1.2: Transport in animals > Flashcards

3.1.2: Transport in animals Flashcards

1
Q

Give the 3 reasons for the need of a transport system in multicellular animals compared to singlecellular

A
  • Bigger organisms : longer diffusion paths between outer body and cells
  • Higher metabollic rate so simple diffusion isn’t fast enough to supply O2
  • Smaller SA:VR : less area for absorption and removal of substances meaning a longer diffusion path
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2
Q

Give 3 features of a mass transport system

A
  • Liquid transport medium that circulates around the system
  • Have vessels that carry the transport medium
  • Have pumping mechanism to move fluid around system
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3
Q

Give examples of where a double closed circulatory system could be found

A

Birds and mammals

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4
Q

Give 2 features of a double closed circulatory system

A
  • Blood passes through heart twice per cycle
  • One circuit carries blood from heart to lungs for gas exchange. Second circuit of blood vessels carries blood from heart to rest of body
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5
Q

Give 2 advantages of double closed circulatory systems

A
  • Allows birds and mammals to remain active and maintain own body temperature
  • Each circuit only passes through 1 capillary network so circulation maintains a higher blood pressure and speed of flow
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6
Q

Give an example of where an open circulatory system would be found

A

Insects

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7
Q

Give 4 features of an open circulatory system in insects

A
  • Transport medium (haemolymph) is pumped directly to open body cavity ( haemocoel)
  • Very few transport vessels
  • Haemolymph at low pressure and transports food and nitrogenous waste
  • Haemolymph returns to heart through open ended vessel
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8
Q

Give 2 disadvantages of an open circulatory systems

A
  • Steep diffusion gradient cannot be maintained as transport medium at low pressure due to no vessels
  • Amount on haemolymph flowing to a particular tissue cannot be varied to meet changing demands
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9
Q

Give examples of where a closed circulatory system could be found

A

All vertebrates such as fish, mammals and worms

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10
Q

Give 3 features of closed circulatory systems

A
  • Transport medium remains inside vessels
  • Gasses and small molecules can leave via diffusion or high hydrostatic pressure
  • Transport O2 (by pigmented protein haemoglobin) and CO2
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11
Q

Give an advantage of closed circulatory systems

A

Amount of blood flowing to a tissue can be varied by widening / narrowing vessels

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12
Q

Give examples of where a single closed circulatory system can be found

A

Fish and annelid worms

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13
Q

Give 2 features of a single closed circulatory system

A
  • Blood passes through heart once per cycle
  • Blood passes through 2 sets of capillaries
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14
Q

How does a single closed circulatory system work in fish ?

A

After being pumped out of the heart, blood flows through capillaries to deliver blood to the body before returning to the heart. Works due to the countercurrent mechanism

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15
Q

Give a disadvantage of single closed circulatory systems

A

Due to passing through narrow capillaries, blood pressure drops so blood returns to heart slowly which limits efficiency of exchange so activity level of animal is low

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16
Q

What is the function of arteries ?

A

Carries (oxygenated except for pulmonary and umbilical artery) blood away from heart to tissues

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17
Q

Describe the thickness of the walls of arteries

A

Thicker than veins to help maintain blood pressure

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18
Q

Describe the lumen and blood pressure of an artery

A

Narrow and high

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19
Q

Do arteries have valves ?

A

No

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20
Q

Describe the structure of arteries

A
  • Smooth muscle : thicker layer than veins to allow constriction and dilation to control the volume of blood
  • Elastic layer : thicker than veins to maintain blood pressure and to enable walls to stretch and recoil in response to the heart beat and prevent bursting
  • Collagen : to provide structural support
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21
Q

What is the function of veins ?

A

Transport deoxygenated blood (except pulmonary veins) away from cells to the heart

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22
Q

Do veins have valves ?

A

Yes

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23
Q

Describe the lumen and blood pressure of valves

A

Wide and low

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24
Q

Describe the structure of valves

A
  • Smooth muscle : thin layer to enable blood to flow easily over it
  • Elastic layer : thin as low blood pressure
  • Collagen : lots to provide structural support throughout network
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25
Q

Describe the wall thickness of veins

A

Thin as low pressure means low risk of vessel bursting and vessel is easily flattened to help the flow of blood to the heart

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26
Q

What is the function of arterioles ?

A

Link arteries and capillaries and prevent fluctuation of blood pressure by the time it reaches the capillaries

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27
Q

Do arterioles have valves ?

A

No

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28
Q

Describe the wall thickness and pressure of arterioles ?

A

Thinner as lower pressure of blood

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29
Q

Describe the structure of arterioles

A
  • Smooth muscle : thicker than arteries to constrict blood flow into capillaries
  • Elastic layer : thinner than arteries as lower pressure
  • Collagen : thinner than arteries
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30
Q

What is the function of capillaries ?

A

Link arterioles with venules by forming a network throughout a tissue to exchange substances

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31
Q

Do capillaries have valves ?

A

No

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32
Q

Describe the lumen and blood pressure within a capillary

A

Small (1 blood cell thick) and low

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33
Q

Describe the wall thickness of capillaries

A

1 cell thick of lining layer which provides short diffusion distance of exchange between blood and cells

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34
Q

What is the function of venules ?

A

Transport blood from capillary into the veins

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35
Q

Do venules have valves ?

A

Yes

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36
Q

Describe the wall thickness of venules

A

Thin wall as several venules join to form a vein

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37
Q

Describe the structure of venules

A

Thin layer of smooth muscle

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38
Q

Define oncotic pressure

A

Pressure created by the osmotic effects of a solute such as proteins

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39
Q

Give an example of oncotic pressure

A

Blood is high in solutes which lowers water potential , creates a pressure and draws water into the blood

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40
Q

Define hydrostatic pressure

A

Pressure exerted by a fluid pushing against the walls of the capillary

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41
Q

Describe the formation of tissue fluid

A
  • Blood at arterial end of capillary is at relatively high hydrostatic pressure which forces water and other small molecules out of capillary by ultrafiltration
  • Tissue fluid ( similar to blood but without plasma proteins) moves into spaces between cells
  • Blood at higher hydrostatic pressure at arterial end as it comes fro the arterioles which have a wider diameter
  • Plasma proteins which remain in blood reduce water potential and exert an oncotic pressure which draws some water back into the capillary
  • At the venous end the blood is under lower hydrostatic pressure meaning the oncotic pressure is greater
  • The net flow of water is therefore into capillaries from spaces between cells
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42
Q

How does hydrostatic pressure vary across a capillary ?

A

Higher at arterial end

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43
Q

How does oncotic pressure vary across a capillary ?

A

Stays the same across the capillary

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44
Q

Describe reabsorption of tissue fluid

A

Excess is drained into the lymphatic system were it becomes lymph and eventually drains back into bloodstream

45
Q

What is lymph ?

A

Colorless yellow fluid, similar composition to plasma but no large plasma protein, less oxygen and less nutrients

46
Q

Where in the heart is there a thicker muscular wall and why ?

A

Left ventricle so it can contract with more force and pump blood at a higher pressure all the way around the body

47
Q

Why do the atria have thin muscular walls ?

A

Blood only needs to be pumped from atria to ventricles with minimum pressure

48
Q

What is the vena cava ?

A

A vein on the right side of the heart which transports blood from the body to the heart

49
Q

What is the pulmonary vein ?

A

A vein on the left side of the body which transports blood from the lungs to the heart

50
Q

What is the pulmonary artery ?

A

An artery on the right side of the body which transports blood from the heart to the lungs

51
Q

What is the aorta ?

A

An artery on the left side of the body which transports blood from the heart to the body

52
Q

What type of muscle is the heart made from ?

A

Cardiac muscle

53
Q

What is a feature of cardiac muscle ?

A

It is myogenic so automatically contracts /relaxes and never fatigues

54
Q

What is the function of the heart

A

An organ responsible for pumping blood around the blood vessels`

55
Q

What is the heart surrounded by ?

A

Pericardial membranes which are inelastic and prevent the heart from swelling with blood

56
Q

What supplies the cardiac muscle with blood and why ?

A

Coronary arteries so that the muscles can aerobically respire to provide ATP for contraction

57
Q

Give the sequence of blood as it does a circuit from and back to the lungs

A

LUNG
Pulmonary vein
Left atrium
Left ventricle
Aorta
BODY
Vena cava
Right atrium
Right ventricle
Pulmonary artery
LUGS

58
Q

What are the steps of the cardiac cycle ?

A
  • Atrial systole
  • Ventricular systole
  • Diastole
59
Q

What happens during atrial systole ?

A
  • Pressure in atria increases until atrioventricular valves are forced open
  • Atria contract and remaining blood flows into ventricles
60
Q

What happens during ventricular systole ?

A
  • High pressure in ventricles which pushes against cusps of atrioventricular valve, shutting it
  • Semi lunar valves open and blood flows into the aorta and pulmonary arteries
  • Ventricles contact
61
Q

What happens during diastole ?

A
  • Atria and ventricles relax and fill with blood from the veins
  • Volume of heart increases and pressure decreases so blood flows through atrioventricular valve
62
Q

How is cardiac output calculated ?

A

Heart rate x stroke volume

63
Q

Define heart rate

A

Beats of heart per minute ( min-1)

64
Q

Define stroke volume

A

Volume of blood that leaves the heart each beat (dm3)

65
Q

What are the sounds of the heart ?

A

‘lub’ ‘dup’

66
Q

What does the ‘ lub’ sound of the heart represent ?

A

Atrioventricular valves closing as ventricles start to contract

67
Q

What does the ‘ dup’ sound of the heart represent ?

A

Semilunar valves closing as ventricles relax

68
Q

Where are the pacemaker cells of the heart ?

A

Sinoatrial node in the walls of the right atrium

69
Q

Why are pacemaker cells needed ?

A

To initiate the process of myogenic contraction

70
Q

How is the rate of contraction of the heart controlled ?

A

By the electrical activity initiated by the sinoatrial node as a pacemaker

71
Q

What causes myogenic contraction ?

A

Muscle cells are myocytes so have a slight electrical charge across their membrane meaning they are polarized so when the charge is reversed they are depolarized which causes them to contract

72
Q

Give the sequence of events for the control of the cardiac cycle

A
  • SAN releases a wave of depolarization across atria
  • Atria contract and pump blood into ventricles
  • AVN releases another wave of depolarization once the first reaches it to delay and allow all the blood to move from atria -> ventricles
  • Wave is transmitted down the bundle of His
  • Wave is conducted down the septum and along the purkinje fibres
  • The apex of the walls of ventricles contract
  • Blood is pumped into arteries
  • Atria and ventricles relax
  • Cells repolarise as cardiac muscle relaxes
73
Q

How is the electrical activity of the heart measured ?

A

Using an ECG to detect waves of depolarization and difference sin electrical activity using electrodes stuck on skin

74
Q

What type of heartbeat is sinus rhythm ?

A

Normal

75
Q

What type of heartbeat is tachycardia ?

A

Fast heart rate over 100bpm

76
Q

What type of heartbeat is bradycardia ?

A

Slow heart rate under 60bpm

77
Q

Where is bradycardia common and how can it be fixed if it becomes a problem ?

A
  • Athletes as cardiac muscle can contract harder so fewer contractions needed to pump blood
  • Artificial pacemaker needed to regulate heartbeat as SAN is not working
78
Q

What is heart fibrillation ?

A

Irregular rhythm of heart

79
Q

What is an ectopic heartbeat ?

A

Additional heartbeats which are not in the normal rhythm

80
Q

What letters can 1 heartbeat by represented by ?

A

PQRST

81
Q

What does a P wave represent ?

A

Electrical activity spreading over atria before atrial systole

82
Q

What does a QRS complex represent ?

A

Electrical activity spreading over ventricles

83
Q

What does a T wave represent ?

A

Ventricles relaxing and repolarisation

84
Q

Describe the structure of haemoglobin

A
  • Groups of globular proteins with a quarternary structure
  • 4 polypeptide chains : 2 alpha , 2 beta sub units
  • Each polypeptide chain has its own non protein prosthetic group attached which contains an iron atom where one molecule of oxygen may bind
85
Q

How many molecules of oxygen may bind per haemoglobin ? Provide an equation

A

4
Hb + 4O2 –> HbO8

86
Q

Give the formula for oxyhaemoglobin

A

HbO8

87
Q

Give relationship between oxygen and haemoglobin

A
  • Haem groups have a high affinity for oxygen
  • Oxygen dissociates from haemoglobin when low O2 concentration as it binds reversibly
88
Q

Give the 2 ways in which haemoglobinic acid can form

A
  • CO2 dissolved in blood plasma
  • CO2 reacts reversibly with amino acids in Hb
89
Q

Give the 3 ways that CO2 can be transported

A
  • Carbaminahaemoglobin
  • Haemoglobinic acid
  • Hydrogen carbonate ions
90
Q

What is the most common form that CO2 is transported as ?

A

Hydrogen carbonate ions

91
Q

Give the process of the transport of CO2 into cells

A
  • CO2 diffuses from bod cells into red blood cells
  • Carbonic anhydrase is an enzyme which combines CO2 and H20
  • Carbonic acid dissociated into H+ ions and hydrogen carbonate
  • Hydrogen carbonate ions diffuse out of red blood cell
  • Simultaneously oxyhaemoglobin dissociates under H+ ion influence
  • O2 is released into blood plasma
  • Haemoglobinic acid forms
  • Chloride shift maintains the neutrality (charge) of red blood cell
92
Q

Why is the oxygen dissociation curve ‘S’ shaped?

A

Due to cooperative nature of O2 binding to haemoglobin .When the first O2 binds it causes an allosteric shape change to haemoglobin which makes it easier for further O2 to bind

93
Q

Where is O2 loaded and offloaded ?

A

Loaded in regions with high partial pressure e.g. alveoli and unloaded in regions with low partial pressure e.g. respiring tissues

94
Q

What is the concentration of O2 measured by ?

A

The relative pressure of gasses in partial pressure

Higher pressure = higher O2 concentration relative to other gasses

95
Q

Describe the Bohr effect

A

When CO2 concentration increases, the O2 dissociation curve shifts to the right as the affinity for O2 decreases

96
Q

Why does an increase in CO2 concentration reduce hemoglobin affinity for oxygen

A

More CO2 means more H+ ions and more dissociation and release of O2 from oxyhaemoglobin which reduces the affinity of oxygen for haemoglobin

97
Q

Describe foetal haemoglobin

A

Has a higher affinity for O2 than adult haemoglobin meaning at the same partial pressure, fetal Hb is more saturated with O2

98
Q

Describe features of haemoglobin in llamas and earthworms

A
  • Llamas live at high altitudes so Hb has a higher affinity for O2 so even in an environment of low partial pressure it can still become saturated with O2
  • Earthworms live at very low altitudes with a low partial pressure
99
Q

Describe features of haemoglobin in doves

A

Dove Hb has a lower affinity to O2 .Hb is less saturated as more O2 has been offloaded. This allows faster metabolism as its a larger animal so there is more O2 for respiration to release energy for muscle contraction

100
Q

What can cause fluctuations in blood pressure throughout the aorta ?

A

Contraction increases blood pressure and relaxation decreases blood pressure

101
Q

Name the process that creates pressure inside the heart chambers

A

Systole

102
Q

Suggest 2 advantages of keeping blood inside vessels

A

-Ensures blood maintains at a higher pressure to be moved around the body
-Increases the rate of flow

103
Q

How are the walls of arteries adapted to withstand pressure ?

A

Thick with elastic collagen and muscle to provide strength so artery walls aren’t damaged as it is stretched

104
Q

How are the walls of arteries adapted to maintain pressure?

A

Elastic fibres enable the artery to stretch and recoil . Thick layer of smooth muscle to constrict artery

105
Q

State 2 ways the wall of an artery is different from the wall of a vein

A

Thicker layer of smooth muscle and thicker layer of collagen

106
Q

How is hydrostatic pressure generated in the heart?

A

Contraction of ventricle walls

107
Q

Why does tissue fluid not contain erythrocytes ?

A

Erythrocytes are too big to fit between endothelium pores

108
Q

Describe the role of haemoglobin in transporting oxygen around the body

A

Haemoglobin has a high affinity for oxygen
O2 binds to haemoglobin in the lungs and is released in tissues where it is needed. When O2 binds it alters the shape of haemoglobin

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