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Biology - Year 12 > Mass transport - Chapter 7 > Flashcards

Mass transport - Chapter 7 Flashcards

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1
Q

MASS TRANSPORT IN ANIMALS

A
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2
Q

What is the function of red blood cells ?

A

Transports oxygen from lungs + deliver it throughout the body

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3
Q

What are red blood cells also known as ?

A

Erythrocytes

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4
Q

What are the 3 adaptations erythrocytes have for transporting oxygen and explain how the consequence of it ?

A
  1. Have a biconcave disk - gives them a large surface area to volume ratio, allowing oxygen to diffuse in and out rapidly
  2. Has a large amount of haemoglobin - for transporting oxygen
  3. No nucleus or organelles - maximises space for haemoglobin/ more volume, so more oxygen can be transported
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5
Q

What is haemoglobin and the structure of it ?

A

Haemoglobin is a large group of globular proteins with a quaternary structure : 4 polypeptide chains (2 alpha + 2 beta polypeptide chains)

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6
Q

What is each polypeptide chain bound to in a prosthetic group, and what does this mean to haemoglobin?

A

A haem group.

Because there are 4 haem groups in each haemoglobin molecule, each molecule (1 molecule) of haemoglobin can bind up to 4 oxygen molecules

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7
Q

What does a haem group contain ?

A

The iron ion (Fe2+), which gives haemoglobin its red colour

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8
Q

When haemoglobin binds to oxygen, what do we now call it, and what type of reaction is it ?

A

We call it oxyhaemoglobin

This reaction is reversible, so oxyhaemoglobin can also release the oxygen required

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9
Q

What does affinity of haemoglobin for oxygen mean ?

A

The ability of haemoglobin to attract/bind to oxygen

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10
Q

What does the saturation of haemoglobin with O2 mean ?

A

When haemoglobin is holding the maximum amount of oxygen it can bind

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11
Q

What is the loading/association of haemoglobin mean ?

A

The binding of O2 to haemoglobin

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12
Q

What does the unloading/dissociation of haemoglobin mean ?

A

When oxygen detaches/unbinds from haemoglobin

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13
Q

How can we measure the amount of oxygen that combines with haemoglobin ?

A

The oxygen dissociation curve

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14
Q

What happens to oxygen in the oxygen dissociation curve ?

A

Oxygen is loaded in regions with a high partial pressure of oxygen (e.g. alveoli) and is unloaded in regions of low partial pressure of oxygen (e.g respiring tissues). This is shown on the oxyhaemoglobin dissociation curve.

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15
Q

What does the dissociation curve illustrate (about affinity and saturation of oxygen) ?

A

It illustrates the change in haemoglobin as partial pressure changes.

The saturation of haemoglobin is affected by its affinity for oxygen, therefore in the case where partial pressure is high, haemoglobin has a high affinity for oxygen and is therefore highly saturated.

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16
Q

The affinity of oxygen for haemoglobin varies depending on the partial pressure of oxygen ( which is a measure of oxygen concentration). What does this mean?

A

The greater the concentration of dissolved O2 in cells, the greater the partial pressure.
Therefore as partial pressure increases, the affinity for haemoglobin of O2 increases. This occurs in the lungs known as loading.

During respiration, oxygen is used up and therefore the partial pressure decreases, so decreasing the affinity of O2 for haemoglobin.
As a result of that, oxygen is released in respiring tissues where it is needed.
After the unloading process, the haemoglobin returns to the lungs where it binds to O2 again.

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17
Q

Where is the loading of haemoglobin/ where there is a high saturation of oxygen/affinity for oxygen ?

A

In the alveoli in the lungs

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18
Q

Where is the unloading of haemoglobin/ where there is a low saturation of oxygen/affinity for oxygen ?

A

Respiring cells

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19
Q

How can saturation have an effect on affinity ?

A

After binding to the first oxygen molecule, the affinity of haemoglobin for oxygen increased due to a change in shape, thus making it easier for the other oxygen molecules to bind to it.

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20
Q

Describe the curve on the graph , where x axis is partial pressure of O2, and y axis is the saturation of haemoglobin with O2. (Curve is an S shape)

A

-At low O2 concentration, little O2 binds to haemoglobin, so joining is slow.
[graph shows initially, curve is shallow as the shape of haemoglobin makes it difficult for first oxygen molecule to bind because sites on its 4 polypeptide subunits are closely united.]

  • when 1st O2 molecule binds, quaternary structure changes, making it easier for more O2 to bind. (so, takes a smaller increase in partial pressure for O2 molecule to bind than 1st).
    -So, the gradient gets steeper :positive cooperativity
  • But after 3rd molecule, harder for final O2 molecule to bind. Majority of binding sites are now filled, so less likely that a single O2 molecule will find site + bind.

So saturation of haemoglobin with increasing pO2 is not linear.

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21
Q

At a low partial pressure of O2, what happens to the affinity + saturation of O2 ?

A

At low partial pressure of O2 (e.g. in respiring tissue during exercise), haemoglobin has a low affinity for oxygen, so it has low saturation of oxygen.

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22
Q

At a high partial pressure of O2, what happens to the affinity + saturation of oxygen ?

A

When partial pressure of O2 is high (e.g. in the lungs), haemoglobin has a high affinity for O2, so it will have a higher O2 saturation.

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23
Q

The affinity of haemoglobin for oxygen is also affected by the partial pressure of carbon dioxide. What happens when the partial pressure of CO2 is high?

A

When partial pressure of CO2 is high in respiring tissue, oxygen dissociates from haemoglobin more easily, this allows more O2 to be unloaded to cells during intense activity.
So, increased respiration increases pCO2.

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24
Q

Why is CO2 released in respiring cells?

A

It requires O2 for the process to occur. Therefore, in the presence of CO2, the affinity of haemoglobin for O2 decreases, thus causing it to be released.

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25
Q

What does an increase in CO2 production lead to (blood pH….)?

A

Leads to a decrease in blood pH as it reacts with water to form carbonic acid. The low pH causes the tertiary structure of the haemoglobin to be altered, decreasing its affinity for O2, so increasing dissociation of O2.

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26
Q

What does an increase in CO2 do to the oxygen dissociation curve, and what is it called ?

A

The increase in CO2 shifts the whole oxygen dissociation curve to the right. This means that carbon dioxide causes the affinity of haemoglobin for oxygen to decrease.

This is called the Bohr effect.

The further left the curve, the higher the haemoglobin’s affinity for O2.

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27
Q

What happens to the curve, affinity + loading of oxygen when there is low partial pressure of O2?

A

Low partial pressure of CO2 in the alveoli. Curve shifts to left, increased affinity and therefore loads more oxygen.

LEFT= LOAD MORE OXYGEN
RIGHT= RELEASE MORE OXYGEN

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28
Q

What happens to the curve, affinity + loading of oxygen when there is high partial pressure of CO2?

A

High partial pressure of CO2 at respiring tissues. Curve shifts to the right, decreased affinity and therefore unloads more oxygen.

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29
Q

Where there is the most respiration occurring ( more CO2 produced), more O2 will be released to help ….

A

Maintain the level of metabolic activity

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30
Q

In the placenta, the fetal blood has a lower level of oxygen (so lower partial pressure of O2) than the maternal blood. What does this cause?

A

This causes oxygen to diffuse across the placenta and into the fetal blood.

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31
Q

Fetal haemoglobin has a different affinity for oxygen compared to adult haemoglobin. Explain, comparing the curves + affinity for oxygen.

A

-The curve for fetal haemoglobin is shifted to the left compared to adult haemoglobin. This means that fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin.
- This higher affinity increased the oxygen transfer across the placenta from the maternal haemoglobin to the fetal haemoglobin.
Therefore, fetal haemoglobin must have a higher affinity for oxygen in order for the foetus to survive at low partial pressure.

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32
Q

CIRCULATORY SYSTEM OF A MAMMAL

A
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33
Q

Why is a circulatory system used?

A

In large organisms, the SA:V ratio is not large enough for diffusion alone to supply substances like oxygen, glucose and other molecules to cells where they are needed. Therefore, a circulatory system is used.

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34
Q

What are the features of a circulatory system and explain?

A

-suitable median : to carry materials.

-means of moving the median : animals often have a pump known as the heart to maintain pressure differences around the body , more rapid than diffusion

  • mechanism to control flow around the body : valves are used in veins to prevent any back flow
  • close system of vessels : the circulatory system in most animals + plants is closed and is browsed to deliver certain substances to all parts of the body.
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35
Q

In mammals, what type of circulatory system do they have ?

A

They have a closed double circulatory system

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36
Q

What does a closed double circulatory system mean?

A

Closed = the blood remains within the bloody vessels
Double circulatory system = heart with 4 chambers. The blood passes through the heart twice in each circuit.
There is one circuit which delivers oxygenated blood to the lungs and another circuit/pump which delivers the oxygenated blood to the rest of the body (to supply vital organs +tissues).

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37
Q

What is a single circulatory system, and what animals has one?

A

Fish have them.

It is a heart with 2 chambers meaning blood passes through the heart once for every circuit of the body.

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38
Q

Why is a closed circulatory system more efficient ?

A

As the blood is forced through fairly narrow tubes so it travels faster and under pressure.

39
Q

3 disadvantages of single circulatory systems in fish ?

A
  • blood flows slow due to low pressure
  • rate of delivery oxygen is limited
  • blood pressure drops as blood passes through gill capillaries
40
Q

Mammals require a double circulatory system to manage the pressure of blood flow. Explain why .

A

The blood flows through the lungs at a lower pressure. This prevents damage to the capillaries in the alveoli and also reduces the speed at which blood flows, enabling more time for gas exchange.

The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that the blood reaches all the respiring cells in the body.

41
Q

The coronary arteries + blood vessels attach to which organs ?

A

Heart, lungs + kidneys

42
Q

What are the blood vessels in the heart ?

A

Vena cava, aorta, pulmonary artery, pulmonary vein

43
Q

What are the blood vessels in the lungs ?

A

Pulmonary artery + pulmonary vein

44
Q

What are the blood vessels in the kidneys ?

A

Renal artery + renal vein

45
Q

These major blood vessels are connected within the circulatory system via what ?

A

The arteries, arterioles, capillaries + veins

46
Q

What are the 2 veins (IN to the heart)

A

Vena cava (means body vein), pulmonary vein

47
Q

Need to know the diagram of a heart and how to draw it

A
48
Q

What does the vena cava do ?

A

Carries deoxygenated blood from the body into the heart (right atrium)

49
Q

What does the pulmonary vein do ?

A

Carries oxygenated blood away from the lungs, to the heart (left atrium)

50
Q

What does the renal vein do ?

A

Carries deoxygenated blood away from the kidneys, towards the heart

51
Q

What are the 2 arteries (Away from the heart) ?

A

Pulmonary artery, aorta

52
Q

What does the pulmonary artery do ?

A

Carries deoxygenated blood from the heart (right ventricle) to the lungs (becomes oxygenated)

53
Q

What does the aorta do ?

A

Carries oxygenated blood from the heart (left ventricle) to the rest of the body

54
Q

What does the renal artery do ?

A

Carries oxygenated blood from the heart towards the kidneys

55
Q

What are the 2 valves?

A

Atrioventricular valves (AV valves), semi-lunar valves (SL valves)

56
Q

What are the AV valves and where are they found ?

Bicuspid -left side, Tricuspid -right side

A

Valves found between the atrium + ventricle only open one way to prevent back flow of blood in the atria when the ventricles contract.
They allow pressure to build in ventricles as they shut when ventricular pressure exceeds atrial pressure.

57
Q

What are the SL valves + where are they found ?

A

Found in the aorta + pulmonary artery
Prevents the back flow of blood into the ventricles when the pressure in these vessels exceeds that in the ventricles

58
Q

What are valves + when do they open and close ?

A

Prevent back flow of blood

They open when pressure is higher behind the valve
They close when pressure is higher in front of the valve

59
Q

What does the septum do ?

A

Separated the deoxygenated + oxygenated blood,

Maintains a high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiratory cells.

60
Q

What does systole + diastole + atria mean ?

A

Systole = “contracting”
Diastole = “relaxing”
Atria = both atriums

61
Q

Explain the cardiac cycle.

A

Both the atria +ventricles are in diastole. Blood flows into the atria through the vena cava + pulmonary vein. This causes the pressure in the atria to rise.

1) Atrial Stage - ventricles are relaxed and atria contract, this decreases their volume and increased their pressure (pressure in atria>pressure in ventricles). This forces the AV valves to open fully, and blood is pushed into the ventricles. Ventricular pressure increases slightly as they fill with blood.

2) Ventricular Systole - [After a short period of time], the atria relax and the ventricles contract. This decreases the volume and increases the pressure (pressure in ventricles> pressure in atria). This forces the AV valves to close. When pressure increases enough, the SL valves are forced open+ blood is pumped in the aorta/ pulmonary artery.

3) Diastole - both atria + ventricles relax. The pressure in the aorta is now higher than the ventricles so the SL valves shut. Then the cycle restarts.

62
Q

Look at the diagram/graph in science book/on photo album for biology about cardiac cycle. Need to know in which bits of the graph does the AV + SV valves open+close.

A
63
Q

What is the structure of the heart ?

A

A system of 2 pumps: the left side pumps oxygenated blood from the lungs to the organs of the body.
The right side pumps deoxygenated blood from the organs of the body to the lungs.

64
Q

What is cardiac muscle + facts ?

A

The walls of the heart have a thick muscular layer, muscle is called cardiac muscle.
It is made up of cardiomyocytes, these are specialised cells which are myogenic.

Myogenic : it can contract+ relax without a nerve impulse to stimulate it.
Cardiac muscle never fatigues, as long as it has a supply of oxygen.

65
Q

What are the coronary arteries ?

A

Supply the cardiac muscle with oxygenated blood (so they never fatigue).
These branch off from the aorta, shortly after it leaves the heart.
Blockage of these arteries (e.g. blood clot), leads to a heart attack because an area of the heart muscle is deprived of blood + oxygen.
The muscle cells in this region are therefore unable to respire and so die (due to cardiac muscle not receiving oxygen).

66
Q

What are the 4 chambers of the heart (4 regions where blood flows into ) ?

A

2 atria - left atrium, right atrium
2 ventricles - left ventricle, right ventricle

67
Q

What are the atria?

A

Thin-walled + elastic.
Elastic walls stretch when blood enters.
Do not need to contract as hard as not pumping blood for (only to ventricles).

68
Q

What are ventricles ?

A

Thicker muscular walls to enable bigger contraction.
This creates a high blood pressure to enable blood to flow longer distances (to the lungs + rest of the body).

69
Q

What does the right ventricle do ?

A

Pumps blood to the lungs.
This needs to be at a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange.
Had thinner muscular walls than left ventricle (as it has a shorter distance to travel).

70
Q

What does the left ventricle do ?

A

Pumps blood to the body.
This needs to be at a higher pressure to ensure blood reaches all the cells in the body.
Therefore, much thicker muscular wall in comparison to the right ventricle to enable larger contractions of the muscle to create higher pressure + due to LV tracking a further distance.

71
Q

What do arteries do ?

A

Carry blood AWAY from the heart and into the arterioles

72
Q

What are arterioles ?

A

The arterioles are smaller than the arteries and connect to the capillaries

73
Q

What do the capillaries connect ?

A

The arterioles to the veins

74
Q

What do the veins do ?

A

The veins carry blood back INTO the heart

75
Q

Describe the process of the blood vessels (arteries, arterioles, capillaries and veins)

A

Arteries branch into arterioles, they contract to restrict blood flow and relax to increase blood flow ~> high pressure
Arterioles branch into capillaries which form networks in tissues : capillary beds
Once exchanged has occurred, deoxygenated blood flows from capillaries into venules, which join to form veins, and blood is transported back into the heart.

76
Q

What are the blood vessel tissue layers, and what do they do ?

A

Smooth muscle layer - contracts to control flow of blood in arteries, arterioles + veins
Elastic layer - allows the vessel to stretch + recoil in arteries, arterioles and veins
Endothelium - thin, inner lining which is smooth to reduce friction in all vessels

77
Q

Arteries facts (what they do, lumen, walls) ?

A

-carry blood away from heart
-narrower lumen to help maintain high pressure
- thick muscular walls + elastic layer allows stretch and recoil in each ventricular contraction to maintain high blood pressure
- endothelium is folded to allow stretching to help maintain high pressure.

78
Q

Veins facts (what they do, lumen, walls) ?

A
  • carry blood TOWARDS the heart
  • wider lumen as blood is at low pressure
  • thinner layer of muscle + elastic tissue
  • have valves to ensure blood does not flow backwards
79
Q

Capillaries facts (wall, diameter, the number of them)

A
  • walls are only “one cell thick” for short diffusion pathway
  • small/narrow diameter (same as RBC) to slow blood flow
  • very close to cells so short diffusion pathway
  • large number of capillaries to increase surface area for gas exchange
  • sign of substance exchange with cells
80
Q

What is the muscle layer in :

Arteries vs arterioles vs veins vs capillaries

A

Arteries : thicker than veins so that constriction + dilation can occur to control volume of blood.
Arterioles : thicker than in arteries to help restrict blood flow into the capillaries.
Veins : relatively thin so it cannot control blood flow
Capillaries : no muscle layer

81
Q

What is the elastic layer in :

Arteries vs arterioles vs veins vs capillaries

A

Arteries : thicker than veins to help maintain blood pressure. The walls can stretch + recoil in response to the heart beat.
Arterioles: thinner than in the arteries as the pressure is lower
Veins : relatively thin as the pressure is much lower
Capillaries : no elastic layer

82
Q

What is the wall thickness in :

Arteries vs arterioles vs veins vs capillaries

A

Arteries : thicker wall than veins to help prevent the vessels bursting due to the high pressure.
Arterioles : thinner as pressure is slightly lower
Veins: thin as pressure is much lower so low risk of bursting. Thinness means vessels are easily flattened, helps flow of blood to the heart.
Capillaries : one cell thick. Provides short diffusion pathway for exchanging materials between the blood + cells.

83
Q

Do they have valves in ?

Arteries vs arterioles vs veins vs capillaries

A

Arteries : No
Arterioles : No
Veins : Yes
Capillaries : No

84
Q

What is tissue fluid ?

A

Fluid that surrounds the cell in tissues and contains water, glucose, amino acids, fatty acids, ions and oxygen (which bathes the tissues).

85
Q

Why is tissue fluid formed ?

A

It is formed due to the fact that capillaries are “one cell thick”. Capillaries have small gaps in the walls so that liquid and small molecules can be forced out.

86
Q

As blood enters the capillaries from the veins, what does the small diameter result in ?

A

High pressure

87
Q

What happens at the arterial end in the tissue fluid process?

A

The high hydrostatic pressure forces small molecules (water, glucose, amino acids, fatty acids, oxygen) are forced out of the plasma (capillaries). This is known as ultrafiltration.

88
Q

What remains in the capillary after ultrafiltration (tissue fluid process) ?

A

Red blood cells, platelets, large proteins : large molecules

89
Q

How are the small molecules reabsorbed back into the capillaries after ultrafiltration (tissue fluid process) ? (Also include talking about what happens at the venule end, HP , which is in next flashcard)

A

Large molecules remain in the capillaries and therefore create a lowered water potential.
So, the water (in the tissue fluid) re-enters the capillaries by osmosis down the water potential gradient.
(No liquid is being forced out now, due to hydrostatic pressure being dropped very low as lots of liquid is being forced out).

90
Q

What happens towards the venule end of capillaries ?

A

The hydrostatic pressure is lowered due to the loss of liquid, but the water potential is very low.
(Liquid now in venule end has a low water potential).

So the water (in the tissue fluid) re-enters the capillaries by osmosis down the water potential gradient.

So at the venule end, there is low pressure in capillaries and low water potential.

91
Q

What is within the water in tissue fluid ?

A

Within the water is dissolved waste molecules that the cells are releasing (CO2 + urea).

92
Q

End process of tissue fluid :
What happens to the rest of the tissue fluid?

A

Not all the liquid will be re absorbed by osmosis, as equilibrium will be reached.
The rest of the tissue fluid is absorbed into the lymphatic system and eventually drains back into the bloodstream, near the heart, via vena cava.

93
Q

What is lymph?

A

Fluid that is absorbed into lymphatic system known as lymph.
Lymph is a colourless/pale yellow fluid like tissue fluid but contains more lipids.

94
Q

How are lymph vessels similar to veins ?

A

Lymph vessels have valves that let fluid enter but not leave them.

Biology - Year 12 (12 decks)

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