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Biology: 3.3 Organisms Exchange Substances with their Environment > 3.3.4 Mass Transport in Animals > Flashcards

3.3.4 Mass Transport in Animals Flashcards

3.3.4.1 Mass Transport in Animals & 3.3.4.2 Mass Transport in Plants

1
Q

(Haemoglobin) Where is human haemoglobin found and what is it’s role?

A

In the red blood cells.
To carry oxygen around the body.

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2
Q

(Haemoglobin) What is haemoglobin? Include it’s structural features.

A

A large protein with a quaternary structure (made up of 4 polypeptide chains). Each molecule of haemoglobin can carry 4 oxygen molecules.

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3
Q

(Haemoglobin) Describe the 4 polypeptide chains in haemoglobin.

A

Each chain has a haem group which contains an iron ion and gives haemoglobin its red colour.

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4
Q

(Haemoglobin) How is oxyhaemoglobin formed? What type of reaction is this.

A

In the lungs, when oxygen joins to the haemoglobin in the red blood cells. This is a reversible reaction.

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5
Q

(Haemoglobin) When an oxygen molecules joins to haemoglobin, what is it referred to as?

A

Association or binding.

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6
Q

(Haemoglobin) When an oxygen molecules leave oxyhaemoglobin, what is it referred to as?

A

Dissociation.

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7
Q

(Haemoglobin) What does affinity for oxygen mean?

A

The tendency a molecule has to bind with oxygen.

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8
Q

(Haemoglobin) What causes haemoglobin’s affinity for oxygen to vary?

A

The conditions it is in - one of which being the partial pressure of oxygen (pO2).

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9
Q

(Haemoglobin) Describe and explain what partial pressure of oxygen (pO2) is.

A

A measure of oxygen concentration. The greater the concentration of dissolved oxygen in cells, the higher the partial pressure.

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10
Q

(Haemoglobin) Why does haemoglobin’s affinity for oxygen increase as pO2 increases? (2)

A
  • Oxygen loads onto haemoglobin to form oxyhaemoglobin where there is a high pO2.
  • Oxyhaemoglobin unloads oxygen where there is a lower pO2.
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11
Q

(Haemoglobin) Describe what happens when oxygen enters blood capillaries at the alveoli in the lungs, regarding pO2, oxygen and haemoglobin. (4)

A
  • Alveoli have a high pO2, so oxygen loads onto haemoglobin to form oxyhaemoglobin.
  • When cells respire they use up oxygen, lowers pO2.
  • Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads oxygen.
  • Haemoglobin returns to lungs to pick up more oxygen.
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12
Q

(Haemoglobin) Describe the affinity for oxygen and pO2 regarding alveoli in lungs. (4)

A
  • High oxygen concentration
  • High pO2
  • High affinity
  • Oxygen loads
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13
Q

(Haemoglobin) Describe the affinity for oxygen and pO2 regarding respiring tissue. (4)

A
  • Low oxygen concentration
  • Low pO2
  • Low affinity
  • Oxygen unloads
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14
Q

(Haemoglobin: Dissociation Curves) What does an oxygen dissociation curve show?

A

How saturated the haemoglobin is with oxygen at any given partial pressure.

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15
Q

(Haemoglobin: Dissociation Curves) What does the affinity of haemoglobin for oxygen affect?

A

How saturated the haemoglobin is.

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16
Q

(Haemoglobin: Dissociation Curves) Why is the graph ‘S-shaped’ and not a straight line?

A

The saturation of haemoglobin can affect the affinity.

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17
Q

(Haemoglobin: Dissociation Curves) Why does the curve have a steep bit in the middle (where it is easy for oxygen to join) and shallow bits at each end (where it is harder).

A

When haemoglobin combines with the first oxygen molecules, its shape alter to make it easier for other oxygen molecules to join.
As the haemoglobin becomes more saturated, it gets harder for oxygen to join.

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18
Q

(Haemoglobin) What is the partial pressure of carbon dioxide (pCO₂ ), and what does it affect?

A

A measure of the concentration of carbon dioxide in a cell. It affects oxygen unloading.

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19
Q

(Haemoglobin) What does haemoglobin do at higher pCO₂?

A

Gives up its oxygen more readily - to get more oxygen to cells during activity.

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20
Q

(Haemoglobin) Describe and explain the Bohr effect.

A

Cells produce CO₂ when they respire.
Raises the pCO₂ and increases rate of 0₂ unloading.
Dissociation curve ‘shifts’ right.
Saturation of blood with 0₂ is lower for a give pO₂.
Meaning more oxygen is being released.

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21
Q

(Haemoglobin) Explain and describe the type of haemoglobin that organisms that live in environments with a low concentration of oxygen will have. As well as the positioning of their dissociation curve.

A

Higher affinity for oxygen than human haemoglobin, because there isn’t much oxygen available, so haemoglobin has to be very good at loading any available oxygen. The dissociation of their haemoglobin is to the left of humans.

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22
Q

(Haemoglobin) Explain and describe the type of haemoglobin that organisms that are very active and have a high oxygen demand will have. As well as the positioning of their dissociation curve.

A

Lower affinity for oxygen than human haemoglobin, because they need their haemoglobin to easily unload oxygen, so that it’s available for them to use. The dissociation curve of their haemoglobin is to the right of humans.

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23
Q

(Haemoglobin) Explain and describe the type of haemoglobin that mammals that are smaller than humans have. As well as the positioning of their dissociation curve.

A

Lower affinity for oxygen than human haemoglobin, because they need their haemoglobin to easily unload oxygen to meet their high oxygen demand (higher SA:VOL ratio). The dissociation curve of their haemoglobin is to the right of the human one.

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24
Q

(The Circulatory System) Why do multicellular organisms, like mammals, need their circulatory system?

A

They have a low SA:VOL ratio, so they need a specialised mass transport system to carry raw materials from specialised exchange organs to their body cells.

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25
Q

(The Circulatory System) What is the circulatory system made up of?

A

The heart and blood vessels.

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26
Q

(The Circulatory System) Where does the pulmonary artery carry blood to and from?

A

To: Lungs
From: Heart

27
Q

(The Circulatory System) Where does the pulmonary vein carry blood to and from?

A

To: Heart
From: Lungs

28
Q

(The Circulatory System) Where does the aorta carry blood to and from?

A

To: Body
From: Heart

29
Q

(The Circulatory System) Where does the vena cava carry blood to and from?

A

To: Heart
From: Body

30
Q

(The Circulatory System) Where does the renal artery carry blood to and from?

A

To; Kidneys
From: Body

31
Q

(The Circulatory System) Where does the renal vein carry blood to and from?

A

To: Vena cava
From: Kidneys

32
Q

(The Circulatory System) What does blood transport around the body?

A

Respiratory gases, products of digestion, metabolic wastes and hormones.

33
Q

(Haemoglobin) What is cooperative binding? (6)

A

Haemoglobin dissociation curve is sigmoidal (S - shaped)

As the partial pressure of oxygen increases…

Binding of the first oxygen molecule to one subunit of deoxyhaemoglobin is difficult.

On binding, the tertiary structure of the haemoglobin changes / molecule changes shape.

Increases affinity for oxygen so the 2nd / 3rd oxygen molecules can bind more easily.

4th molecule of oxygen will only bind at higher partial pressures (high probability of association)

34
Q

(The Circulatory System) Can you describe the general pattern of blood circulation in a mammal? (8)

A

Left ventricle
Aorta/arteries
Capillaries (body cells)
Veins (vena cava)
Right atrium to right ventricle
Pulmonary artery
Capillaries (lungs/alveoli)
Pulmonary vein to left atrium

35
Q

(The Circulatory System) Describe the two circuits of the system.

A

One circuit takes blood from the heart to the lungs, then back to the heart.
The other loop takes blood around the rest of the body, so the blood has to go through the heart twice to complete one full circuit of the body.

36
Q

(The Circulatory System) What is the heart’s own blood supply?

A

The left and right coronary arteries.

37
Q

(The Circulatory System) What is the function of arteries?

A

To carry blood from the heart to the rest of the body. All arteries carry oxygenated blood expect for the pulmonary arteries, which take deoxygenated blood to the lungs.

38
Q

(The Circulatory System) Describe the structure of arteries.

A

Thick and muscular walls that have elastic tissue to stretch and recoil as the heart beats, which maintains the high pressure. The inner lining (endothelium) is folded, allowing the artery to stretch - also maintains blood pressure.

39
Q

(The Circulatory System) What is the function of arterioles?

A

Blood is directed to different areas of demand in the body by muscles inside the arterioles, which contract to restrict the blood flow or relax to allow full blood flow.

40
Q

(The Circulatory System) What are arterioles?

A

Smaller vessels that form a network throughout the body due to the division of arteries.

41
Q

(The Circulatory System) What is the function of veins?

A

Take blood back to the heart under low pressure. All veins carry deoxygenated blood (as oxygen has been used up by body cells), expect for the pulmonary vein, which carry oxygenated blood to the heart from the lungs.

42
Q

(The Circulatory System) Describe the structure of veins.

A

Wider lumen that equivalent arteries, with very little elastic/muscle tissue. Contain valves to stop the blood flowing backwards. Blood flow through the veins is helped by the contraction of the body muscles surrounding them.

43
Q

(The Circulatory System) What is the function of capillaries?

A

Substances (e.g. glucose and oxygen) are exchanged between cells and capillaries, so they are adapted for efficent diffusion.

44
Q

(The Circulatory System) Why are capillaries always found very near cells in exchange tissues (e.g. alveoli in the lungs)?

A

So that there is a short diffusion pathway.

45
Q

(The Circulatory System) Describe the structure of capillaries.

A

Walls are one cell thick, which shortens diffusion pathway.

46
Q

(The Circulatory System) Why is there a large number of capillaries?

A

To increase the surface area for exchange.

47
Q

(The Circulatory System) What are capillary beds?

A

Networks of capillaries in tissue.

48
Q

(The Circulatory System) What is tissue fluid?

A

Fluid that surrounds the cells in tissue.

49
Q

(The Circulatory System) What is tissue fluid made from?

A

Small molecules that leave the blood plasma, e.g. oxygen, water and nutrients.

50
Q

(The Circulatory System) What do cells take in and release from tissue fluid?

A

They take in oxygen and nutrients from the tissue fluid, and release metabolic waste into tissue fluid.

51
Q

(The Circulatory System) What causes substances to move out of the capillaries and into the tissue fluid in a capillary bed?

A

Pressure filtration.

52
Q

(The Circulatory System) Describe the hydrostatic pressure and its effects at the start of the capillary bed, nearest the arteries.

A

The hydrostatic (liquid) pressure is greater inside the capillaries than in the tissue fluid. The difference in pressure means an overall outward pressure forces fluids out of the capillaries and into the spaces around the cells, forming tissue fluid.

53
Q

(The Circulatory System) Describe the hydrostatic pressure and its effects as fluid leaves.

A

The hydrostatic pressure reduces in the capillaries (lower at the venule end of the capillary bed)

54
Q

(The Circulatory System) Describe the effects of fluid loss regarding capillary beds.

A

Increasing concentration of plasma proteins (which don’t leave the capillaries), water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid. This means that some water re-enters the capillaries from the tissue fluid at the venule by osmosis.

55
Q

(The Circulatory System) What happens to excess tissue fluid?

A

It is drained into the lymphatic system, which transports this excess fluid from the tissues and passes it back into the circulatory system.

56
Q

(The Circulatory System) How is the left ventricle adapted to do its job effectively?

A

Thicker, more muscular walls than the right ventricle - allows it to contract more powerfully and pump blood all the way around the body.

57
Q

(The Circulatory System) How are the ventricles adapted to do its job effectively?

A

Thicker walls than the atria therefore they can push blood out of the heart, whereas the atria only needs to push blood into the ventricles (short distance).

58
Q

(The Circulatory System) How are the atrioventricular (AV) valves adapted to do its job effectively?

A

Link to the atria to the ventricles and stop blood flowing back into the atria when the ventricles contract.

59
Q

(The Circulatory System) How are the semi-lunar (SL) valves adapted to do its job effectively?

A

Link the ventricles to the pulmonary artery and aorta, and stop blood flowing back into the heart after the ventricle contract.

60
Q

(The Circulatory System) How are the cords adapted to do its job effectively?

A

Attach the atrioventricular valves to the ventricles to stop them being forced u into the atria when the ventricles contract.

61
Q

(The Circulatory System) Describe how heart valves function.

A

If there is higher pressure behind the valve, it is forced open, if the pressure is higher in front of the valve, it is forced shut.
This means the flow of blood is unidirectional (flows in one direction).

62
Q

(The Circulatory System) Describe the 1st part of the cardiac cycle, where the ventricles relax and the atria contracts.

A

Ventricles relax.
Atria contract, decreasing volume of the chambers and increasing the pressure behind chambers.
This pushes the blood into the ventricles.
Slight increase in ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria.

63
Q

(The Circulatory System) Describe the 1st part of the cardiac cycle, where the ventricles contract and the atria relaxes.

A

Atria relax.
Ventricles contract (decreasing volume), increasing pressure.
Pressure becomes higher in ventricles than atria.
Forces AV valve shut (prevent back-flow).
Pressure in ventricles is higher than in aorta and pulmonary artery, which forces SL valves open and blood is forced out of arteries.

64
Q

(The Circulatory System) Describe the 1st part of the cardiac cycle, where the ventricles relax and the atria relax.

A

Ventricles and aorta relax.
Higher pressure in pulmonary artery and aorta closes SL valve to prevent back-flow into ventricles.
Blood returns to heart and atria fill again due to higher pressure in vena cava and pulmonary vein.
Increase pressure in atria.
Ventricles continue to relax, pressure falls below pressure of atria.
AV valves open.
Blood flows passively into ventricles from atria.
Atria contracts, cycle begins again.

Biology: 3.3 Organisms Exchange Substances with their Environment (6 decks)

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