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AS Biology > Module 3.2 - Transport in Animals > Flashcards

Module 3.2 - Transport in Animals Flashcards

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1
Q

What are the reasons that multicellular organisms need transport systems?

A

> Relatively big - have a low S/A:vol ratio.
Higher metabolic rate.
Very active.

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2
Q

What is a metabolic rate?

A

The speed at which chemical reactions take place.

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3
Q

Why does multicellular organisms being active mean that they need transport systems?

A

It means that a large number of cells are all respiring very quickly, so they need a constant, rapid supply of oxygen and glucose.

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4
Q

What type of transport system do mammals have?

A

A circulatory system which uses blood to carry glucose and oxygen around the body. It also carries hormones, antibodies and waste (such as CO2).

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5
Q

What is the difference between a single or a double circulatory system?

A

In a single circulatory system, blood only passes through the heart once for each complete circuit of the body whereas it passes through twice in a double circulatory system.

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6
Q

How does the circulatory system in fish work?

A

In fish, the heart pumps blood to the gills (to pick up oxygen) and then on through the rest of the body (to deliver the oxygen) in a single circuit.

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7
Q

Describe how the double circulatory system in mammals works?

A

In mammals, the heart is divided down the middle:

1) The right side of the heart pumps blood to the lungs (picks up oxygen).
2) From the lungs it travels to the left side of the heart, which pumps it to the rest of the body.
3) When blood returns to the heart, it enters the right side again.

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8
Q

The circulatory system is basically two linked loops. What is the system that sends blood to the lungs called?

A

Pulmonary system.

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9
Q

What is the system that sends blood to the rest of the body called?

A

The systematic system.

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10
Q

What is one advantage of the mammalian double circulatory system?

A

The heart can give the blood an extra push between the lungs and the rest of the body which makes the blood travel faster so oxygen is delivered to the tissues more quickly.

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11
Q

What is the difference between closed or open circulatory systems?

A

All vertebrates have closed circulatory systems where the blood is enclosed inside blood vessels whereas, some invertebrates (e.g. invertebrates) have an open circulatory system where blood isn’t enclosed in blood vessels all the time, it flows freely through the body cavity.

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12
Q

Describe the stages of how a closed circulatory works?

A

1) The heart pumps blood into arteries which branch out into millions of capillaries.
2) Substances like oxygen and glucose diffuse from the blood into the capillaries into the body cells, but the blood stays inside the blood vessels as it circulates.
3) Veins take the blood back to the heart.

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13
Q

Describe the stages of how an open circulatory works in insects?

A

1) The heart is segmented, it contracts in a wave, starting from the back, pumping the blood into a single main artery.
2) The artery opens up into the body cavity.
3) The blood flows around the insect’s organs, gradually making its way back into the heart segments through a series of valves.

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14
Q

What does the circulatory system in insects transport and what does it not transport?

A

Supplies the insect’s cells with nutrients, and transports things like hormones around the body.
>But it doesn’t supply the cells with oxygen - this is done by a system of tubes called the tracheal system.

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15
Q

Where do arteries carry blood from and to?

A

Arteries carry blood from the heart to the rest of the body.

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16
Q

Describe the structure of arteries?

A

> Their walls are thick and muscular and have elastic tissue to stretch and recoil as the heart beats, which helps maintain high pressure.
The inner lining (endothelium) is folded, allowing the artery to expand, also helps maintain high pressure.
Relatively small lumen.

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17
Q

Do arteries carry deoxygenated or oxygenated blood? Any exceptions?

A

Arteries carry oxygenated blood except for the pulmonary arteries, which take deoxygenated blood to the lungs.

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18
Q

What do arteries branch into and how are they similar/different to arteries?

A

Arterioles which are smaller than arteries.
>Like arteries, arterioles have a layer of smooth muscle but have less elastic tissue. The smooth muscle allows them to expand or contract, thus controlling the amount of blood flowing to tissues.

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19
Q

What do arterioles branch into and what are their function?

A

Capillaries, which are the smallest type of blood vessel.
>Substances like glucose and oxygen are exchanged between cells and capillaries, so they’re adapted for efficient diffusion being only one cell thick.

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20
Q

What do capillaries connect to next in the circulatory system?

A

Capillaries connect to venules, which have very thin walls that can contain some muscle cells. Venules join together with veins.

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21
Q

Describe the function and structure of veins?

A

Veins take blood back to the heart under a low pressure.
>Have a wider lumen than equivalent arteries, with very little elastic or muscular tissue.
>Contain valves to prevent the blood from flowing backwards.
>Blood flow through the veins is helped by contraction of the body muscles surrounding them.

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22
Q

Do veins carry deoxygenated or oxygenated blood? Any exceptions?

A

Deoxygenated blood apart from the pulmonary veins, which carry oxygenated blood to the heart from the lungs.

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23
Q

What is tissue fluid?

A

Tissue fluid is the fluid that surrounds cells in tissues.

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24
Q

How is tissue fluid made?

A

It’s made from substances that leave the blood plasma such as water, oxygen and nutrients.

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25
Q

What do cells take in from tissue fluid and what do they release into it?

A

Cells take in oxygen and nutrients from the tissue fluid and release metabolic waste into it.

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26
Q

Describe pressure filtration of tissue fluid in terms of hydrostatic pressure and at the beginning of the capillary bed?

A

1) At the start of the capillary bed the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid. This difference in hydrostatic pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid.
2) As fluid leaves, the hydrostatic pressure reduces in the capillaries and so is lower at the end of the capillary bed thats nearest to the venules.

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27
Q

Describe pressure filtration of tissue fluid in terms of oncotic pressure and at the end of the capillary bed?

A

1) Oncotic pressure is also generated by plasma proteins present in the capillaries which lower the water potential. At the venule end of the capillary bed, the water potential is lower in the capillaries than in the tissue fluid due to the fluid loss from the capillaries and the high oncotic pressure.
2) This means that some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.

28
Q

What happens to the excess tissue fluid which doesn’t re-enter the capillaries at the venule end of the capillary bed?

A

The extra fluid eventually gets returned to the blood through the lymphatic system -a kind of drainage system, made up of lymph vessels.

29
Q

What is it called when it is inside the lymph vessels?

A

Lymph.

30
Q

Where does lymph go to in the body?

A

Lymph gradually moves towards the main lymph vessels in the thorax (chest cavity) where it’s returned to the blood, near the heart.

31
Q

What substances compose blood?

A

Red blood cells, white blood cells, platelets, proteins, water and dissolved solutes.

32
Q

Describe the composition of tissue fluid?

A

> No red blood cells, too big to get through capillary walls into tissue fluid.
Very few white blood cells - only enter tissue fluid if the capillaries are damaged.
No platelets
Only antibodies - most proteins are too big to get through capillary walls.
Water - tissue fluid has a higher water potential than blood.
Dissolved solutes - can move freely between blood, tissue fluid and lymph.

33
Q

Describe the composition of lymph?

A 
>No red blood cells.
>Most white blood cells are in the lymph system.
>No platelets.
>Very few proteins.
>Water and dissolved solutes.
34
Q

Why are there no red blood cells in tissue fluid or lymph?

A

Red blood cells and platelets are too big to get through capillary walls into tissue fluid.

35
Q

Describe the position of the main blood vessels in the heart?

A

Right - Vena Cava (superior and inferior), pulmonary artery, aorta, pulmonary veins - Left

36
Q

How do valves work?

A

The valves only open one way. If there is high pressure behind a valve it’s forced open but if the pressure is higher in front of valve, it’s forced shut.

37
Q

What are the two types of valves in the heart and where are they?

A

> Atrioventricular valve - Link the atria to the ventricles.

>Semilunar valve - Link the ventricles to the pulmonary artery.

38
Q

Why is the wall of the left ventricle in the heart so much thicker than on the right?

A

The left ventricle wall is thicker and more muscular than the right, in order to push blood all the way round the body.

39
Q

What is the first stage of the cardiac cycle?

A

> The ventricles are relaxed.
The atria contract, decreasing their volume and increasing their pressure.
This pushes blood into the ventricles through the atrioventricular valves.
Slight increase in ventricular pressure and volume as they receive the ejected blood from the contracting atria.

40
Q

What is the second stage of the cardiac cycle?

A

> The atria relax.
The ventricles contract increasing their pressure.
The pressure becomes higher in the ventricles than the atria, which forces the atrioventricular valves shut to prevent back flow.
The high pressure in the ventricles opens the semilunar valves - blood is forced out into the pulmonary artery and aorta.

41
Q

What is the final stage of the cardiac cycle?

A

> Ventricles and atria both relax
The higher pressure in the pulmonary artery and aorta causes the semi-lunar valves to close, preventing back-flow.
The atria fill with blood (increasing their pressure) due to the higher pressure in the vena cava and pulmonary vein.
As the ventricles continue to relax, their pressure falls below the pressure in the atria.
This causes the atrioventricular valves to open and blood flows passively (without being pushed by atrial contraction) into the ventricles from the atria.
The atria contract and the whole process begins again.

42
Q

What does it mean that cardiac (heart) muscle is myogenic?

A

It can contract and relax without receiving signals from nerves. The pattern of contractions controls the regular heartbeat.

43
Q

What does SAN stand for?

A

Sino-atrial node.

44
Q

Where is the SAN and what is its function?

A

It is in the wall of the right atrium and it is like a pacemaker - it sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls. This causes the right and left atria to contract at the same time.

45
Q

What prevents the waves of electrical activity from being passed directly from the atria to the ventricles?

A

A band of non-conducting collagen tissue.

46
Q

Where do the waves of electrical activity transfer from the SAN?

A

To the atrioventricular node (AVN)

47
Q

What happens at the AVN?

A

It’s responsible for passing the wave of electrical activity on to the bundle of His but there is a slight delay before the AVN reacts, to make sure the ventricles contract after the atria have emptied.

48
Q

What are the bundle of His and what is their function?

A

The bundle of His is a group of muscle fibres responsible for conducting the waves of electrical activity to the finer muscle fibres in the right and left ventricle walls, called the Purknye tissue.

49
Q

What does the purknye tissue do?

A

Carries the waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously, from the bottom up.

50
Q

What does an electrocardiograph record?

A

The electrical activity of the heart - the heart muscle depolarises (loses electrical charge) as it contracts and depolarises (regains charge) when it relaxes.

51
Q

What are the P, Q, S, R and T waves caused by?

A

P - Caused by contraction (depolarisation) of the atria.
QRS complex - The main peak of the heartbeat, together with the dips at either side are caused by the contraction (depolarisation) of the ventricles.
T - Due to the relaxation (depolarisation) of the ventricles.

52
Q

What does the height of the wave indicate?

A

The height of the wave indicates how much electrical charge is passing through the heart - a bigger wave means more electrical charge so (for the P and R waves) a stronger contraction.

53
Q

What is tachycardia?

A

Where the heartbeat is too fast (around 120bpm) whic might be okay during exercise but shows that the heart isn’t pumping blood efficiently.

54
Q

What is the heart problem if the heart has a bpm of below 60?

A

This is called bradycardia where the heartbeat is too slow.

55
Q

What is an ectopic heartbeat and what is it caused by?

A

It is an ‘ extra’ heartbeat. Caused by earlier contraction of the atria or ventricles than in previous heartbeats. Occasional ectopic heartbeats in a healthy person don’t cause a problem.

56
Q

What is an irregular heartbeat called, what is it caused by and what effects can it have?

A

This is fibrillation. The atria or ventricles completely lose their rhythm and stop contracting properly. It can result anything from chest pain, fainting to lack of pulse and death.

57
Q

Describe how oxyhaemoglobin forms?

A

In the lungs, oxygen joins to the iron in haemoglobin and since it has a high affinity for oxygen each molecule can carry 4 oxygen molecules. This is a reversible reaction - when oxygen leaves oxyhaemoglobin (dissociates from it) near the body cells it turns back to haemoglobin.

58
Q

What does ‘affinity’ for oxygen mean?

A

Means tendency to combine with oxygen.

59
Q

What is the partial pressure of oxygen?

A

A measure of oxygen concentration.

60
Q

How does haemoglobin’s affinity for oxygen depend on the partial pressure of oxygen?

A

Oxygen loads onto haemoglobin to form oxyhaemoglobin where there is a high partial pressure of oxygen (pO2) and oxyhaemoglobin unloads its oxygen at lower pO2s.

61
Q

Why is the oxygen dissociation curve S-shaped?

A

Because when haemoglobin combines with the first oxygen molecule, its shape alters in a way that makes it easier for other molecules to join too. But as the haemoglobin starts to become saturated, it gets harder for more oxygen molecules to join.

62
Q

Where in the body would haemoglobin have a high saturation of oxygen (lots of oxyhaemoglobin) and why?

A

The alveoli in the lungs for they have a high pO2.

63
Q

Why does fetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?

A

> The fetus gets oxygen from its mother’s blood across the placenta.
By the time the mother’s blood reaches the placenta, the oxygen saturation has decreased (some has been used up by the mother’s body).
For the fetus to get enough oxygen to survive its haemoglobin has to have a higher affinity for oxygen.

64
Q

Why does haemoglobin give up its oxygen more readily at higher partial pressures of carbon dioxide?

A

A way of getting more oxygen to cells during cell activity for as cells respire they produce carbon dioxide, which raises the pCO2, increasing the rate of oxygen unloading.

65
Q

Describe how carbon dioxide affects oxygen unloading?

A

> Most of the CO2 from respiring tissues diffuses into red blood cells where it reacts with water to form carbonic acid, catalysed by the enzyme carbonic anhydrase.
The carbonic acid dissociates to give H+ ions and hydrogencarbonate ions (HCO3-)
This increase in H+ ions causes oxyhaemoglobin to unloads its oxygen so haemoglobin can take up the H+ ions forming haemoglobinic acid.
The HCO3- ions diffuse out of the red blood cells and transported into the blood plasma. To compensate for this, CI- ions diffuse into the red blood cells. This is called the chloride shift and maintains the balance of charge between the red blood cells and the plasma.
When the blood reaches the lungs the low pCO2 causes some of the HCO3- and H+ to recombine into CO2 (and water)
The CO2 then diffuses into the alveoli and breathed out.

66
Q

What is the Bohr effect?

A

When carbon dioxide levels increase, the dissociation curve ‘shifts’ right, showing that more oxygen is released from the blood.

AS Biology (12 decks)

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