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Biology > Module 3.1.2 - Transport in animals > Flashcards

Module 3.1.2 - Transport in animals Flashcards

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1
Q

What are the specialised features of an erythrocyte?

A

Flattened bi-concave shape (large SA to volume ratio).
Large amount of haemoglobin for transporting oxygen.
No nuleus or organelles so more space for haemoglobin for oxygen.
Diameter 6-8micrometers, larger than capillary diameter. Slows blood flow to enable diffusion of oxygen.

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2
Q

What is the size of an erythrocyte and how does this help it’s function?

A

Small diameter of 7 micrometers, normal cell is 40 micrometers diameter.
Therefore haemoglobin is very close to the plasma membrane - as a result oxygen is loaded and unloaded into and out of a cell.
Capillaries are 8 micrometers wide, only one erythrocyte can go through at a time.

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3
Q

What is haemoglobin?

A

A protein making up 95% of the dry mass of a RBC. It is the means of oxygen transport around a body.

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4
Q

What is haemoglobin’s structure?

A

Haemoglobin is made from four haemoglobin groups each bound to a haem group.
Each haem group can combine with one oxygen molecule, so one haemoglobin molecule can combine with four oxygen molecules. This forms oxyhaemoglobin.

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5
Q

What ion does haemoglobin contain at the centre?

A

The haem group contains a single iron ion in the form Fe 2+.

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6
Q

True or false. Haemoglobin has a high affinity for oxygen?

A

True.

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7
Q

How is the saturation of haemoglobin measured?

A

As a percentage.

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8
Q

What is positive cooperativity?

A

As soon as one oxygen binds to a haem group, it changes the shape of the molecule and makes it easier for more oxygen to bind.
Because the oxygen is binded to the haemoglobin the free oxygen concentration gradient in the erythrocytes remains low, so a steep concentration gradient is maintained until all of the haemoglobin is saturated with oxygen.

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9
Q

When does oxygen bind to and leave haemoglobin?

A

Oxygen binds to haemoglobin when oxygen is at a high concentration and dissociates when oxygen is at a low concentration.

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10
Q

How is oxygen concentration measured?

A

The concentration of gas in a mixture of gases can be measured as the partial pressure. This is the amount of pressure the gas exerts relative to the total pressure exerted by all the gases in the mixture.
Measured with kilopascals (kPa) and is written as P(O2), P(O2) etc

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11
Q

What is the oxygen dissociation curve?

A

A graph that shows the saturation of haemoglobin at various partial pressures of oxygen.

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12
Q

LOOK AT POWERPOINT OR BOOKLET FOR OXYGEN DISSOCIATION CURVE GRAPHS.

A
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13
Q

What is the trend with oxygen dissociation?

A

Generally, the greater the concentration of oxygen, the greater the affinity.
In the lungs the partial pressure is high so haemogloin has a 95-97% saturation of haemoglobin.
At respiring tissues, partial pressure is low, so haemoglobin loses oxygen to 20-25% concentration.

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14
Q

How is fetal haemoglobin different to adult haemoglobin?

A

Fetal haemoglobin has a higher affinity for oxygen.
This is because fetal haemoglobin has to associate with oxygen in an environment where partial pressure of oxygen is low enough to make adult haemoglobin release oxygen.
Helps maximise uptake of oxygen from the mother’s bloodstream.

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15
Q

What are the 3 ways that carbon dioxide are transported?

A

About 5% is carrier dissolved in the plasma.
10-20% is combined with the amino groups of haemoglobin to form carbaminohaemoglobin.
75-80% is converted to hydrogen carbonate ions in the cytoplasm of red blood cells which then diffuses into the plasma.

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16
Q

What factors affect oxygen dissociation?

A

Saturation.
Chemical and physical factors such as pH.

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17
Q

What does the Bohr shift describe and how is this shown on a graph?

A

The affect of high CO2 concentrations on haemoglobin’s affinity for oxygen.
A second line is drawn to the right of and below the standard curve.

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18
Q

How does carbon dioxide affect haemoglobin’s affinity for oxygen?

A

An increase in CO2 in a tissue, such as during exercise, lowers it’s pH. This lowers the oxygen affinity over all partial pressures, leading to increased release of oxygen where it is needed. This is known as the Bohr shift.

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19
Q

How does temperature affect oxygen dissociation?

A

A decrease in temps increase haemoglobin’s affinity for oxygen slightly. This means that hypothermia reduces the blood’s ability to release oxygen into metabolising tissue.

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20
Q

Why do large multicellular organisms need a transport system in relation to metabolic rate?

A

Large multicellular organisms have a high metabolic rate and require high volumes of substances and produce lots of waste. Diffusion alone would not be able to intake and expel all of these substances.

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21
Q

What are the features of a circulatory system for multi-cell animals?

A

A heart.
A fluid in which substances are transported.
Vessels through which the fluid can flow.

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22
Q

What are the two types of circulatory systems?

A

Open and closed.

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23
Q

What are the features of an open circulatory system?

A

It consists of a heart that pumps a fluid called haemolymph through short vessels and into a large cavity called the haemocel.
In the haemocel, the fluid bathes organs and tissues, enabling the diffusion of substances.
When the heart relaxes, the haemolymph is sucked back in via pores called ostia.
Haemolymph moves around the haemocel due to movement of the organism.

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24
Q

What are the limitations with the open circulatory system?

A

Steep concentration gradients cannot be maintained for efficient diffusion.
The amount of haemolymph flowing cannot be varied to meet changing demands.

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25
Q

What are the features of a closed circulatory system?

A

Blood is fully enclosed within blood vessels at all times. It doesn’t directly come into contact with cells in the body.
Blood is pumped from the heart through progressively smaller vessels, at the capillaries substances diffuse in and out of the blood and cells.
Blood then returns to the heart via progressively larger vessels.

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26
Q

What are the advantages and disadvantages of a single circulatory system?

A

Advantages - Less complex

Disadvantages - Low blood pressure, slow movement of blood, Activity levels of the organism tend to be low

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27
Q

What are the advantages and disadvantages of a double circulatory system?

A

The heart can pump blood further round the body.
High pressure.
Fast flow of blood.

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28
Q

What are the 5 types of blood vessels?

A

Arteries.
Arterioles.
Capillaries.
Venules.
Veins.

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29
Q

Where do arteries and arterioles carry blood to and from?

A

Carry oxygenated blood from the heart to the body cells.

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30
Q

Where do veins and venules carry blood to and from?

A

Carry deoxygenated blood from the body cells to the heart.

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31
Q

What are the 3 components of blood vessels and what are their purpose?

A

Elastic fibres - Made of elastin, they stretch and recoil providing the vessel with flexibility.

Smooth muscle - Contracts and relaxes changing the size of the lumen.

Collagen - Provides structural support to maintain shape and volume of the vessel.

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32
Q

What is the function of the arteries?

A

Carry blood away from the heart at high pressure.

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33
Q

What is the structure of arteries?

A

Thicker elastic layer / elastin, enables them to withstand, pressure / force and enables them to, stretch & recoil

The elastic layer evens out surges from the pumping of the heart and allows a continuous flow of blood

Collagen provides, structure / support and maintains shape and volume (limiting stretch).

Smooth muscle contracts and relaxes to, change the size of the
lumen / control blood pressure. It also provides strength to withstand the pressure.

Smooth endothelial lining to allow blood to flow easily over it

34
Q

What is the difference between arteries and arterioles?

A

Much smaller lumen.
Arterioles have much more smooth muscle and less elastic fibres (elastin)
They have little pulse surge.
They constrict and dilate to control blood flow.

35
Q

What is the function of capillaries?

A

Allow substances to be exchanged / diffuse between blood and tissue fluid / surrounding cells.

36
Q

What is the structure of capillaries?

A

Walls are one cell thick.
Short diffusion distance.
Only large enough to allow red blood cells to travel through in single file (to increase contact of RBCs with capillary wall).
Small enough to form network needed to exchange substances.

37
Q

What is the function of veins and venules?

A

Veins carry blood back to the heart.
No, pulse / surge from heart. Blood in veins is under less pressure (than in arteries). Needs to move against gravity.

38
Q

What is the structure of veins and venules?

A

Thinner elastic layer (no,
stretch / recoil / pulse).
Have valves to prevent backflow of blood.
More collagen than arteries to give structural support as they carry large volumes of blood.

39
Q

What are the differences between veins and venules?

A

Venules have very thin walls with just a little smooth muscle.
Several venules split from one vein

40
Q

How do valves help blood flow?

A

Prevent backflow of blood.

41
Q

How does bigger veins running between the big active muscles help with blood flow?

A

When the muscles contract, they squeeze the veins, forcing blood towards the heart.

42
Q

How do breathing movements help with blood flow?

A

In the chest this aids the movement of blood.

43
Q

What are varicose veins and where does this occur?

A

If a vein wall becomes weakened, valves may no longer close properly, this allows backflow of blood, causing the vein to become bumpy and enlarged.
Usually happens in superficial veins near the surface in the lower legs.
They can be surgically removed without affecting blood flow as most is returned to the heart by deep veins.

44
Q

What happens to blood pressure as blood moves through arterioles to capillaries and then venules and veins?

A

Velocity and pressure drop continuously.

45
Q

What is blood?

A

It is the specialised transport medium of the human circulatory system, it is also considered a special type of connective tissue.

46
Q

How much blood does an adult have on average?

A

4-6 litres.

47
Q

What functions does blood have?

A

Transport,
Defence,
Thermoregulation,
Maintaining pH of body fluids.

48
Q

What substances do blood transport?

A

Oxygen.
Carbon dioxide.
Nitrogenous waste products to excretory organs.
Hormones.
Food molecules from storage compounds to cells.
Digested food from SI.
Platelets to damaged areas.
Cells and antibodies involved in immune response.

49
Q

What is the composition of blood?

A

Cells (45%) - erythrocytes, leukocytes, thrombocytes (platelets)

Plasma (55%) - water, proteins (albumin, fibrinogen, antibodies), ions, nutrients, waste products, hormones, gases.

50
Q

What are the features of plasma?

A

Yellow liquid that carries a wide variety components other than the RBC, WBC and platelets such as dissolved glucose, amino acids, mineral ions, hormones and large plasma proteins.

51
Q

What are the plasma proteins and what are they important for?

A

Albumin - important in maintaining the osmotic potential of the blood.
Fibrinogen - important in blood clotting.
Globulins - involved in the immune system.

52
Q

What is the total volume of blood in the human body?

A

5dm^3

53
Q

What is the average number of red blood cells?

A

2.5 x 10^-15

54
Q

Average number of red blood cells?

A

5 x 10^-11

55
Q

Average number of platelets?

A

6 x 10^12

56
Q

What are the similarities and differences between blood plasma and tissue fluid?

A

It is similar to blood plasma but doesn’t contain most of the cells in blood.
Doesn’t contain plasma proteins.
It is mainly water and small molecules.

57
Q

What are the features of tissue fluid?

A

Formed by plasma leaking out of the capillaries.
Surrounds the cells in the tissues, supplies them with oxygen and nutrients.
Mass flow of blood plasma from capillaries into tissue fluid, waste products go the opposite way.

58
Q

How is tissue fluid formed?

A

At the arteriole end of a capillary the blood is at a relatively high hydrostatic pressure.
The pressure tends to push the blood fluid out of the capillaries through the capillary wall.
The fluid leaves through tiny gaps (pores) between the endothelial cells in the capillary wall.
This is ultrafiltration.
Exchange then occurs into and out of the cells by diffusion, facilitated diffusion and active transport.

59
Q

What is hydrostatic pressure?

A

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

60
Q

How is fluid returned to the capillary from the tissue fluid?

A

The blood pressure at the venous end of the capillary is much lower.
This allows some of the tissue fluid to return to the capillary carrying CO2 and other waste substances into the blood.
Not all tissue fluid re-enters the blood.
About 10% of the tissue fluid is directed into the lymphatic system.
This drains excess tissue fluid out of the tissue and returns it to the blood system in the subclavian vein in the chest.

61
Q

What else has an influence on movement of fluid in and out of a capillary apart from hydrostatic pressure?

A

Oncotic pressure.

62
Q

What is oncotic pressure?

A

It is the pressure created by the osmotic effects of the solutes, most notably the plasma protein albumin.

63
Q

What does oncotic pressure depend on and why?

A

Depends on the concentration of large plasma proteins and not other solutes because the large plasma proteins cannot pass out through the capillary walls / leave the blood, but other solutes can.

64
Q

What results in oncotic pressure?

A

An imbalance of large plasma proteins between blood and tissue fluid.

65
Q

How is oncotic pressure created?

A

Plasma proteins are too large to leave the capillaries so this creates a low water potential in the capillary.
The water potential is lower than in the tissue fluid, water moves, by osmosis into the capillary, causing the pressure.

66
Q

Draw a capillary showing oncotic pressures and hydrostatic pressures at arteriole and venule ends.

A

…

67
Q

True or false, the oncotic pressure is the same at either end of the capillary.

A

True

68
Q

Is the hydrostatic pressure higher at the venous end or arteriole end of the capillary?

A

Arteriole end.

69
Q

Does hydrostatic pressure drive fluid in or out of the capillary and why?

A

Out, because hydrostatic pressure is the same within the tissue fluid and is always lower than within the capillary.

70
Q

What is the net driving force and what does it determine?

A

It is the net effect of oncotic and hydrostatic pressure that determines whether fluid will be forced in or out of the capillary.

71
Q

What is lymph fluid and what is it composed of?

A

It is the fluid in the lymphatic system. It is similar to tissue fluid but also contains lipids.
It also contains lymphocytes which are produced in lymph nodes which play an important role in the immune system.

72
Q

What does the lymphatic system consist of?

A

Lymphatic capillaries and vein-like lymph vessels, containing valves.
Lymph nodes - sac like organs that trap pathogens and foreign substances, and which contain large numbers of white blood cells.
Lymphatic tissue - in the spleen, thymus and tonsils - these also contain large amounts of WBC and are involved in their development.

73
Q

How old is the foetus when it’s heart starts beating?

A

5-6 weeks.

74
Q

What muscle does the heart consist of and what are it’s features?

A

The heart mainly consists of cardiac muscle which is like smooth muscle (but not skeletal muscle), contracts involuntary.
It is made up of cells that are connected by cytoplasmic bridges. This enables electrical impulse to pass through the tissue.
It contains large numbers of mitochondria and myoglobin molecules.

75
Q

What happens during atrial systole?

A

The muscles of the atria contract.
The pressure inside the atria increases.
The tricuspid and bicuspid atrioventricular valves opens, allowing blood into the ventricles.
Pressure decreases.

76
Q

What happens during ventricular systole?

A

Muscles of the ventricles contract.
The pressure inside the ventricles increases.
The tricuspid and bicuspid atrioventricular valves close.
The semi-lunar valves in the aorta and the pulmonary arteries open.
Pressure decreases.

77
Q

What happens during diastole?

A

Pressure in the ventricles decreases.
The semi-lunar valves in the aorta and pulmonary arteries close.
All the heart muscles contract.
Blood flows into the atria from vena cava and pulmonary vein.
Blood pressure remains low inside the atria and ventricles

78
Q

Explain the shape of the pressure change graph in the heart.

A

…

79
Q

What do valves in the heart do?

A

They prevent backflow in the heart.
They are controlled by pressure changes in the heart chambers.

80
Q

What is the equation for cardiac output?

A

heart rate x stroke volume

81
Q

What is stroke volume?

A

volume of blood pumped out of the left ventricle during 1 cardiac cycle.

82
Q
A

Biology (18 decks)

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