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A level Biology > 3.2 transport in animals > Flashcards

3.2 transport in animals Flashcards

1
Q

what are the 3 reasons for the need for transport systems

A

size
surface area to volume ratio
metabollic activity

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2
Q

why does size influence the need for a transport system

A

the innermost cells in an organism are further away increasing diffusion distance.
the diffusion rate is reduced and is too slow to supply oxygen and nutrients to the respiring tissues
The outer layer of cells also uses up the supplies so less reaches the cells deep inside the body

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3
Q

How does the surface area to volume ration influence the need for a transport system

A

small animals have a high SA:V meaning for each gram of body tissue they have sufficient surface area through which exchange can occur

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4
Q

how does metabolic activity influence the need for an exchange system?

A

releasing energy from food during aerobic respiration requires oxygen so an active animal requires a good supply of oxygen and nutrients for energy especially animals that keep themselves warm

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5
Q

What are features of an efficient transport system

A

A fluid or medium to transport oxygen and waste in

a pump to create pressure that will push the fluid around

exchange surfaces that enable substances to enter and leave the blood

tubes or vessels to carry the blood by mass flow

two circuits

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6
Q

What is a single circulatory system?

A

E.G. fish

blood flows through the heart once for every circuit

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7
Q

What is a double circulatory system?

A

E.G. mammals

the system has two separate circuits where one carries deoxygenated blood to the lungs and one where oxygenated blood is carried to the tissues
heart - body - heart - lungs - heart

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8
Q

What are the advantages of a double circulatory system?

A

the heart can increase the blood pressure after it has passed through the lungs so blood is under higher pressure and flows quicker
allows greater flow of blood to the tissues
enables high metabolic activity

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9
Q

Why can’t pressure be too high in the pulmonary circulation?

A

may damage the delicate capillaries in the lungs

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10
Q

What is an open circulatory systems

A

where the blood isn’t held in the vessels and instead circulates in the body cavity so the tissues are bathed directly in the blood

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11
Q

What are the disadvantages of open circulatory systems?

A

blood pressure and flow is low
circulation of blood may be affected by body movements or lack of them

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12
Q

what is a closed circulatory system?

A

Where the blood is contained in vessels

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13
Q

What are the advantages of a closed circulatory system?

A

higher pressure do blood flows more rapidly
more rapid delivery of oxygen and nutrients
more rapid removal of CO2 and other waste
transport is independent of body movements

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14
Q

what are the blood vessels called

A

arteries
arterioles
capillaries
veins
venules

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15
Q

what is the structure of an artery

A

lumen
endothelium
elastic fibres
smooth muscle
collagen fibres

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16
Q

What is the function of the arteries?

A

arteries carry blood away from the heart

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17
Q

How are arteries adapted to their function

A

the blood is at high pressure so the artery wall must be thick in order to withstand that pressure
the lumen is also relatively small to maintain high pressure
the inner wall is folded to allow lumen to expand as blood flow increases

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18
Q

how are arterioles adapted to their function

A

they are small blood vessels that distribute blood from the artery to the capillary
arteriole walls contain a layer of smooth muscle which contracts and constricts the diameter of the arteriole increasing resistance to the flow of blood reducing its rate

constriction of the arteriole can also be used to divert the flow of blood to regions of the body which require more oxygen

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19
Q

what is the structure of capillaries?

A

they have very thin walls and are one cell thick and consist of one layer of flattened endothelial cells
they have leaky walls

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20
Q

how does the structure of capillaries relate to their function

A

their thinner lumen causes red blood cells to be squeezed against its walls reducing diffusion distance

they are one cell thick so this reduces diffusion distance further

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21
Q

What is the function of venules?

A

they consist of thin layers of muscle and elastic tissue and blood flows from the capillaries to the venules

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22
Q

What is the structure of veins

A

veins have a relatively large lumen and thin layers of smooth muscle and collagen and elastic tissue

lumen
endothelium
elastic fibres
smooth muscle
collagen fibres

they contain valves

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23
Q

How is the structure of the veins related to their function

A

veins carry blood back to the heart at a relatively low pressure so the walls do not need to be thick
the layers of elastic fibres, smooth muscle and collagen fibres do not need to be thick as they don’t need to stretch and recoil and aren’t actively constricted to reduce blood flow

veins also contain valves to prevent the backflow of blood

the thin walls can be flattened by the action of the surrounding skeletal muscles and applies pressure to the blood.

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24
Q

define hydrostatic pressure

A

pressure that a fluid exerts when pushing against the sides of a vessel or container.

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25
Q

Define oncotic pressure

A

the pressure created by the osmotic effects of the solutes

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26
Q

what is tissue fluid

A

the fluid surrounding cells and tissues

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27
Q

what is tissue fluid composed of

A

similar to blood plasma but doesn’t contain most of the cells found in blood plasma or plasma proteins

so it contains many dissolved substances such as oxygen carbon dioxide minerals amino acids glucose etc.

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28
Q

How is tissue fluid formed (summary)

A

as blood plasma leaks from the capillaries it carries all the dissolved substances into the tissue fluid

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29
Q

How would you describe the movement of blood plasma from the capillaries

A

mass movement rather than diffusion

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30
Q

How does tissue fluid form? (detailed )

A

at the arterial end of a capillary the blood is at a relatively high hydrostatic pressure and this pressure tends to push the blood fluid out of the capillary walls

the fluid that leaves the blood consists of plasma with dissolved nutrients and oxygen and the cells that are too large to be pushed through the gaps such as erythrocytes tend to remain in the blood

The tissue fluid surrounds the body cells so exchange of gases and nutrients can occur across the plasma membranes

oxygen and other nutrients enter the cells and carbon dioxide and other waste products leave the cells

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31
Q

How does tissue fluid return to the blood?

A

the blood pressure at the venous end of the capillary is much lower allowing some of the tissue fluid to return to the capillary carrying co2 and other waste products

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32
Q

where does some tissue fluid go if not the blood

A

some tissue fluid is directed to the lymph system which drains the excess tissue fluid out of the tissues and returns it to the blood system in the subclavian vein in the chest

33
Q

what influences the movement of fluids in the capillaries

A

hydrostatic pressure of the blood tends to push fluids out of the blood and into the tissues

the hydrostatic pressure of the tissue fluid tends to push fluid into the capillaries

the oncotic pressure of the blood tends to pull water back into the blood so it has a negative figure (venule end)

the oncotic pressure of the fluid tends to pull water into the tissue fluid

34
Q

give a simple description of the heart

A

the heart is a muscular pump with two sides

the right side pumps deoxygenated blood to the lungs to be oxygenated
the left side pumps oxygenated blood to the rest of the body

35
Q

What are some external features of the heart?

A

it is made of cardiac muscles and has a coronary artery that provides it with oxygenated blood

36
Q

describe the flow of blood through vessels of the heart

A

deoxygenated blood flows from the vena cava to the right atrium and oxygenated blood flows through the pulmonary vein to the left atrium

from the atria blood flows through the atrio-ventricular valves to the ventricles and these valves have tendinous cords attached to them to prevent them from turning inside out when the ventricles contract

the septum separates the ventricles from one another

oxygenated blood flows through the aorta from the left ventricle to the rest of the body and deoxygenated blood flows through the pulmonary artery from the right ventricle to the lungs and through the semi-lunar valves

37
Q

describe the structure of the chambers in the heart

A

Atria - the walls of the atria are rather thin because these chambers do not need to create a large amount of pressure

37
Q

describe the structure of the chambers in the heart

A

Atria - the walls of the atria are rather thin because these chambers do not need to create a large amount of pressure

right ventricle - the wall of the right ventricle are thicker than those of the atria as it pumps deoxygenated blood to the lungs, the alveoli are very delicate and can be damaged by high pressure

left ventricle - the walls of the left ventricle are thicker than that of the right as the blood needs to be pumped to the rest of the body and needs sufficient pressure to overcome the resistance of systemic circulation

38
Q

What is the definition of the cardiac cycle?

A

The events that occur in one heartbeat

39
Q

What occurs during atrial systole

A

both right and left atria contract and a small increase in pressure occurs helping to push blood into the ventricles

40
Q

What occurs during ventricular systole

A

both left and right ventricles contract at their base so blood is pushed up towards the arteries

41
Q

What occurs during diastole

A

The muscular walls of all four chambers relax and elastic recoil allows the chambers to expand creating a decrease in pressure and allowing blood to flow in from the veins

42
Q

Describe the action of the atrio-ventricular valves during systole

A

blood in the atria pushes the atrio-ventricular valves open and the valves remain open while the atria contract but close when the atria begin to relax and this closure is caused by the swirling action of blood in the ventricles

higher blood pressure behind valve causes it to open but a higher pressure in front causes it to close and low pressure behind cannot open the valve

43
Q

Describe the action of the semi-lunar valves during systole

A

before ventricular contraction the pressure in the major arteries is higher than that of the ventricles so they remain closed

ventricular systole raises the blood pressure in the ventricles very quickly and once the pressure is above that of the major arteries they open

during diastole when pressure in the ventricles drops below that of the major arteries the semi-lunar valves close so blood doesn’t flow back into the ventricles

44
Q

describe the pressure in blood vessels

A

the further the blood flows along the arteries the more pressure drops and fluctuations become less obvious

45
Q

Define bradycardia

A

a slow heart rhythm

46
Q

define an ectopic heartbeat

A

an extra beat or an early beat of the ventricles

47
Q

Define an electrocardiogram

A

trace that records the electrical activity of the heart

48
Q

Define fibrillation

A

uncoordinated contraction of the atria and ventricles

49
Q

define myogenic muscle

A

muscle that can initiate its own contraction

50
Q

define purkyne tissue

A

specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles

51
Q

describe the sino-atrial node

A

small patch of tissues that send waves of excitation at regular intervals to initiate contractions

52
Q

Define tachycardia

A

a rapid heart rhythm

53
Q

How do the contractions at the atria and ventricles differ

A

the atrial muscles tend to contract at a higher frequency

54
Q

How is the contraction of the heart initiated

A

the SAN initiates a wave of excitation at regular intervals

55
Q

Describe the contraction of the atria

A

wave of excitation spreads over the walls of the atria and travels along the membranes of the muscle tissue causing the cardiac muscles to contract

56
Q

Why does the heart contain collagen which can’t conduct electricity

A

Makes sure there is a delay in contractions of the ventricles and atria by ensuring that the SAN excitation wave doesn’t pass to the ventricles and cause them to contract

57
Q

describe the contraction of the ventricles

A

After a short delay the wave of excitation is carried away from the AVN and down conducting tissue called PURKYNE tissue

this runs down the interventricular septum and at the base of the septum the wave of excitation spreads out and upwards the walls of the ventricles

58
Q

describe the pqrst waves in an electrocardiogram

A

p - excitation of the atria
qrs - ventricular stimulation
t- diastole

59
Q

Describe the association of oxygen with haemoglobin

A

association of oxygen and haemoglobin occurs at areas of high pO of oxygen such as the lungs and dissociates at areas with a low pO of oxygen such as respiring tissues

60
Q

What affects the ability of haemoglobin to associate with oxygen

A

the concentration of oxygen in the surrounding tissue

61
Q

describe how haemoglobin associates with oxygen

A

haemoglobin doesn’t readily associate with oxygen because the haem groups are in the centre of the haemoglobin molecule making it difficult to reach

once an oxygen molecule associates with the haem group it causes a conformational change allowing more oxygen to enter the molecule easier

62
Q

how does foetal haemoglobin differ to that of adults

A

foetal haemoglobin must be able to associate with oxygen in an environment where oxygen tension is low enough to make adult haemoglobin release oxygen

63
Q

define chloride shift

A

movement of chloride ions into the erythrocytes to balance the charge as hydrogencarbonate ions leave the blood cell

64
Q

Describe the formation of hydrogencarbonate ion

A

carbon dioxide diffuses into the blood plasma and then the red blood cells where it combines with water to create carbonic acid catalysed by CARBONIC ANHYDRASE
which the dissociates to release H+ ions and HCO3- ions

65
Q

describe what occurs after carbonic acid dissociates in the red blood cells

A

HCO3- ions diffuse out of the red blood cells into the blood plasma the charge inside the red blood cells is maintained by a chloride shift

Build up of the H+ ions causes the contents of the red blood cell to become more acidic and to prevent this they are taken out of the solution by associating with haemoglobin to produce haemoglobonic acid

66
Q

What is the effect of increasing carbon dioxide concentration

A

causes oxyhaemoglobin to dissociate more due to the decreased oxygen tension

67
Q

What is the bohr effect

A

co2 enters the red blood cell to form carbonic acid and dissociates to release H+ ions

these H+ ions affect the pH of the cytoplasm and can affect the tertiary structure of haemoglobin reducing its affinity for oxygen and making it release the oxygen

68
Q

What is the bohr shift

A

downwards shift in the haemoglobin dissociation curve

69
Q

how do you calculate cardiac output

A

stroke volume * heart rate

70
Q

what does tachycardia imply

A

the heart isn’t pumping blood efficiently

71
Q

what does bradycardia imply

A

electrical activity issue, not passing on from SAN correctly

72
Q

describe the bohr effect in terms of the graph

A

at the same oxygen tension the percentage saturation is lower because more oxygen dissociates

73
Q

how do we know that when the first oxygen binds the quaternary shape of haemoglobin is altered

A

small increase in concentration, but very steep concentration

74
Q

How does size affect haemoglobin

A

smaller animals have a higher SA:V so they lose heat rapidly and have a higher metabolic rate and need it to have a lower oxygen affinity

75
Q

how does your environment affect haemoglobin

A

low oxygen environments need haemoglobin to have a higher oxygen affinity - left shift

76
Q

How does activity level affect haemoglobin

A

need to be able to quickly dissociate oxygen to ensure that when there is more respiration occurring more O2 will be released to maintain a high metabolic rate so a low affinity is needed

77
Q

What occurs at low pCO2

A

(lungs) causes some of the HCO3- ions to associate with H+ ions and CO2 diffuses into the alveoli

78
Q

Why do H+ ions cause oxygen dissociation

A

as the H+ ions bind to the haemoglobin instead to form haemoglobonic acid

A level Biology (25 decks)

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