3.2 Transport in Animals Flashcards

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1
Q

How are substances transported in single-celled organisms ?

A

Substances diffuse across an outer membrane.

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2
Q

How are substances transported in multicellular organisms ?

A

Use transport systems, such as circulatory systems for more efficient transport around the organism.

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3
Q

Why do multicellular organisms use transport systems ?

A

Large organisms, so have a small SA: volume ration and a higher metabolic rate. They are also more active so need a constant supply of glucose and oxygen. CO2 also needs to be removed quickly.

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4
Q

What are circulatory systems ?

A

Use blood to carry glucose and oxygen around the body. They also transport hormones, antibodies and waste products.

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5
Q

What is a single circulatory system ?

A

When blood only passes through the heart once in each complete circuit.

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6
Q

What is a double circulatory system ?

A

When blood passes through the heart twice in each complete circuit.

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7
Q

What is a closed circulatory system ?

A

All vertebrates have a closed circulatory system, where the blood is enclosed inside blood vessels.

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8
Q

What is an open circulatory system?

A

Some vertebrates have an open circulatory system, where blood isn’t enclosed in blood vessels all the time. Instead it flows freely through the body cavity.

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9
Q

What are arteries ?

A

They are blood vessels that carry blood away from the heart to the rest of the body. They carry oxygenated blood, except from the pulmonary arteries.

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10
Q

Why do arteries have thick, muscular walls ?

A

They need to withstand the high pressure as the heart beats.

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11
Q

Why do arteries have elastic tissues ?

A

They need to stretch and recoil as the heart beats.

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12
Q

Why is the inner lining of arteries folded ?

A

The endothelium is folded allowing it to contract.

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13
Q

What are arterioles ?

A

Branched from arteries and are much smaller. They have a layer of smooth muscle and has less elastic tissue.

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14
Q

Why does arterioles have smooth muscle in rings around arterioles ?

A

Allows them to expand or contract controlling amount of blood flowing to the tissues.

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15
Q

What are capillaries ?

A

Arterioles split into capillaries, which are the smallest blood vessel. Transports substances such as oxygen and glucose, which are exchanged between cells and capillaries.

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16
Q

How are capillaries adapted for gas exchange ?

A

They are one cell thick, so decreases diffusion distance making gas exchange more efficient.

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17
Q

What are venules ?

A

Capillaries connect to venules, which have thin cell walls that contain some muscle cells. Venules join together to form veins.

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18
Q

What are veins ?

A

Take blood back to heart under a low pressure. They contain valves to stop back flow of blood. All veins carry deoxygenated blood except for the pulmonary vein.

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19
Q

Why do veins have a wide lumen and little elastic or muscle tissue ?

A

Low pressure so don’t need to be as strong to withstand pressure. Wide lumen to allow more blood to flow back to heart.

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20
Q

What helps veins transport blood back to the heart ?

A

Skeletal muscles help blood flow travel back to heart through veins.

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21
Q

What is tissue fluid ?

A

Surrounds cells in tissues. It is made from substances that leave blood plasma.

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22
Q

What is the function of tissue fluid ?

A

Cells take in oxygen and nutrients from the tissue fluid and release metabolic waste into it. Substances move out of capillaries into tissue fluid, by pressure filtration.

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23
Q

What is the pressure like at capillary bed at start of pressure filtration ?

A

At start of capillary bed, nearest arteries, hydrostatic pressure inside capillaries is greater than hydrostatic pressure in tissue fluid.

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24
Q

What does a difference in hydrostatic pressure cause in pressure filtration ?

A

Forces fluid out of capillaries and into spaces around cells, forming tissue fluid.

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25
Q

What happens when tissue fluid leaves capillaries in pressure filtration ?

A

Hydrostatic pressure reduces in capillaries, so hydrostatic pressure is much lower at end of capillary bed, nearest venules.

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26
Q

What happens as water leaves the capillaries in pressure filtration ?

A

Concentration of plasma proteins in capillaries increases and water potential decreases.

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27
Q

What do plasma proteins generate in capillaries in pressure fluid ?

A

Plasma proteins in capillaries generate form of pressure, oncotic pressure, so at venule end of capillary bed, there is increased oncotic pressure and low water potential.

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28
Q

What occurs due to water potential gradient in capillaries in pressure filtration ?

A

Because water potential in capillaries is lower than water potential in tissue fluid, some water then re-enters capillaries ,from tissue fluid, at venule end of osmosis.

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29
Q

What happens to extra fluid that doesn’t re-enter capillaries ?

A

Extra tissue fluid gets returned to the blood through the lymphatic system (drainage system).

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30
Q

What are the smallest lymph vessels ?

A

Lymph capillaries, where excess fluid passes into.

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31
Q

What happens to excess fluid once it is inside the lymphatic system ?

A

Valves in lymph vessels stop lymph going backwards. Lymph gradually moves toward main lymph vessels in thorax.

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32
Q

What is the left side of the heart responsible for ?

A

Pumps oxygenated blood to the rest of the body.

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33
Q

What is the right side of the heart responsible for ?

A

Pumps deoxygenated blood to the lungs.

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34
Q

What is the atrioventricular valve ?

A

Links atria to the ventricles.

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35
Q

What is semi-lunar valve ?

A

Links ventricles to pulmonary artery and aorta..

36
Q

What is the purpose of valves in the heart ?

A

They stop blood flowing the wrong way, so prevents back flow.

37
Q

What does the valve opening depend on ?

A

Valves only open one way and whether they are open or closed depends on relative pressure of heart chambers. If there is a higher pressure behind valve, it is forced open. If there is a higher pressure in front of valve, it is forced shut.

38
Q

What is the direction of blood flow described as ?

A

Unidirectional.

39
Q

What is the cardiac cycle ?

A

Describes events in a single heartbeat. It is the ongoing sequence of contraction and relaxation of the atria and ventricles.

40
Q

When atria and ventricles contract and relax, what does this cause ?

A

Volumes of atria and ventricles change, which alters pressure. This causes valves to open and close, which moves blood through the heart.

41
Q

What is stage 1 of the cardiac cycle ?

A

The ventricles are relaxed and the atria contract, increasing pressure in atria and pushes blood into ventricles, through atrioventricular valves.

42
Q

What is stage 2 in cardiac cycle ?

A

The atria relax and ventricles contract and pressure becomes higher in ventricles, which forces atrioventricular valves to shut. Pressure in ventricles is higher than aorta and pulmonary artery, which forces blood into these arteries.

43
Q

What is stage 3 in cardiac cycle ?

A

Ventricles and atria relax. Higher pressure in pulmonary artery and aorta closes semi-lunar valves. Blood returns to the heart and atria fills again due to higher pressure in vena cava and pulmonary vein. Pressure in atria increases so atrioventricular valves open.

44
Q

What is cardiac output ?

A

Volume of blood pumped by heart per minute.

45
Q

How do you calculate cardiac output ?

A

heart rate (bpm) x stroke volume (cm3)

46
Q

What is stroke volume ?

A

Volume of blood pumped during each heartbeat.

47
Q

Why is the cardiac muscle myogenic ?

A

As it can contract and relax without receiving signals from nerves. This pattern controls a heartbeat.

48
Q

What is the Sino-atrial node ?

A

Where process starts and is found in the wall of the right atrium. It sets the rhythm of the heartbeat by sending regular waves of electrical actiivy over atrial walls causing both atria to contract.

49
Q

What is the non-conducting collagen tissue responsible for ?

A

Prevents waves of electrical activity from being passed directly from atria to ventricles.

50
Q

What is the atrio-ventricular valve ?

A

Responsible for passing waves electrical activity to the Bundle of His. There is a slight delay to ensure ventricles contract.

51
Q

What is the Bundle of His ?

A

Group of muscle fibres responsible for conducting waves of electrical activity to finer muscle fibres to R+L ventricle wall - Purkyne tissue.

52
Q

What is the purkyne tissue ?

A

Carries electrical waves into muscular walls of R+L ventricles, so they contract simultaneously, bottom upward.

53
Q

What are electrocardiogram ?

A

A machine that records electrical activity. Heart depolarises (loses electrical charge) when it contracts and repolarises when it relaxes. Used with electrodes on a persons chest.

54
Q

What are electrocardiographs ?

A

A trace produced by an electrocardiogram.

55
Q

What is a P wave ?

A

Wave caused by contraction of atria.

56
Q

What is the QRS complex ?

A

Main peak with dips either side and is the contraction of ventricles.

57
Q

What is the T wave ?

A

Cause by relaxing of ventricles.

58
Q

What does the heigh of the wave show ?

A

Indicates how much electrical charge is passing through the heart.

59
Q

How do you calculate heart rate ?

A

60/ time taken for 1 heartbeat (s)

60
Q

What is tachycardia ?

A

When the heart beats too fast. This is normal for exercise but can be dangerous if this is an individual’s resting heart rate.

61
Q

What is bradycardia ?

A

When the heartbeat is too slow - around 50bpm. This may be normal for a resting athlete, but could indicate a problem in normal people.

62
Q

What is fibrillation ?

A

This is an irregular heartbeat. The atria/ ventricles completely loose their rhythm. This can result in chest pain etc.

63
Q

What is an ectopic heartbeat ?

A

When there is an extra heartbeat that interrupts a regular rhythm. This is caused by an earlier contraction of the atria or ventricles than in previous heartbeats. This can happen in health people.

64
Q

What is haemoglobin ?

A

Found in red blood cells and carries oxygen around then body. It is a quaternary protein, made up of 4 polypeptide chains. Each chain has a ham group that contains iron, giving blood a red colour.

65
Q

How many oxygen molecules can haemoglobin carry ?

A

4 oxygen molecules.

66
Q

What is oxyhaemaglobin ?

A

When oxygen form with iron in haemoglobin.

67
Q

What is association/ loading ?

A

When oxygen joins to haemoglobin.

68
Q

What is disassociation/ unloading ?

A

When oxygen leaves oxyhaemaglobin.

69
Q

What is the affinity of oxygen ?

A

Affinity is the tendency for a molecule to bind with oxygen.

70
Q

What is partial pressure for oxygen ?

A

This is a measure of oxygen concentration. Greater concentration go dissolved oxygen cells increases partial pressure. Haemoglobin affinity depends on this.

71
Q

Does oxyhaemaglobin have a low of high partial pressure for oxygen ?

A

High partial pressure as oxygen is loaded to this. When oxygen disassociates from oxyhaemaglobin, partial pressure decreases.

72
Q

Do alveoli have a low or high partial pressure for oxygen ?

A

High partial pressure as oxygen enters blood from capillaries in the alveoli. When cells respire, they use oxygen so partial pressure of oxygen lowers in the alveoli.

73
Q

What is a disassociation curve ?

A

Shows how saturated haemoglobin is with oxygen at any given partial pressure. Affinity for oxygen affects how saturated haemoglobin is.

74
Q

Why does dissociation curve form an s-shape ?

A

When haemoglobin first binds with oxygen, its shape alters making it easier for other oxygen molecules to join to the haemoglobin. As haemoglobin becomes more saturated, the harder it is for oxygen molecules to bind to it.

75
Q

What is fetal haemoglobin ?

A

Haemaglobin with a higher affinity for oxygen so is better at absorbing oxygen than adult blood. Fetus gets oxygen from mother’s blood across the placenta.

76
Q

Does blood passing through the placenta have a low or high partial pressure for oxygen ?

A

Has a low partial pressure for oxygen as by time blood has reached placenta, some has been used up in mothers body, so oxygen saturation has decreased. Fatal haemoglobin takes up oxygen in lower partial pressure for oxygen.

77
Q

What is the partial pressure for carbon dioxide ?

A

Measure of carbon dioxide in a cell. This affects the oxygen disassociation.

78
Q

Why does carbon dioxide partial pressure affect oxygen disassociation ?

A

This is because haemoglobin gives up oxygen more readily at a higher partial pressure of carbon dioxide so more oxygen is reaching cells during activity.

79
Q

What is the Bohr effect ?

A

When saturation of blood with oxygen is lower, partial pressure of oxygen is lower so more oxygen is released.

80
Q

What occurs in the Bohr effect ?

A

Most of carbon dioxide diffuses in red blood cells. It reacts with water to form carbonic acid, which is catalysed by enzyme carbonic anhydrase. The rest of carbon dioxide binds directly to haemoglobin and is carried to the lungs.

81
Q

What does carbonic acid disassociate into ?

A

Forms H+ and HCO3- ions.

82
Q

What is the equation for the Bohr effect ?

A

CO2 + H20 = H2CO3 = H+ + HCO3-

83
Q

What does an increase in H+ ions cause in Bohr effect ?

A

Causes oxyhemoglobin to unload its oxygen so that haemoglobin can uptake H+ ions. This forms haemoglobin acid, which stops H+ ions increasing cells acidity.

84
Q

What happens to HCO3- ions in Bohr effect ?

A

They diffuse out of red blood cells and are transported in blood plasma.

85
Q

What compensates loss of HCO3- ions ?

A

Cl- ions diffuse into red blood cells. This is called the chloride shift and It maintains balance of charge between red blood cells and plasma.

86
Q

What happens when blood in lungs has a low partial pressure for CO2 ?

A

Some HCO3- ions recombine into CO2 and water. CO2 then diffuses into alveoli and is breathed out.