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Biology AQA A-Level > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

What is the primary structure of haemoglobin?

A

The sequence of amino acids in the four polypeptide chains.

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2
Q

What is the secondary structure of haemoglobin?

A

How each polypetide chain is coiled into a helix

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3
Q

What is the tertiary structure of haemoglobin?

A

Is each polypeptide chain is coiled into a precise shape

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4
Q

What is the quarternary structure of haemoglobin?

A

How all four polypeptide chains are linked together to form a spherical molecule. Each polypeptide is assoicated with a haem group, which contains a ferrous (Fe 2+ ion). Each ferrous ion can combine with one O2 molecule.

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5
Q

What is the process of loading oxygen?

A

Where haemoglobin binds/associates with O2 in the lungs.

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6
Q

What is the process of unloading oxygen?

A

Where haemoglobin releases/dissociates with it’s O2 in the tissues.

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7
Q

What is an affinity for oxygen?

A

High affinity more readily binds with O2 but releases it less easily.
Low affinity less easily binds with O2 but releases it more readily.

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8
Q

How is haemoglobin efficient at transporting oxygen?

A
  • Must readily associate with O2 at the surface where gas exchange takes place.
  • Must readily dissociate from O2 at those tissues requiring.
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9
Q

How does haemoglobin change shape to be efficient at transporting O2?

A

It shape changes in the presence of CO2 to bind more loosely and so releases O2.

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10
Q

What is an oxygen dissociation curve?

A

The graph of the relationship between between the saturation of haemoglobin with O2 and oxygens partial pressure

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11
Q

Why does little O2 bind to haemoglobin when O2 concentrations are low, how does this refelct on graph?

A

The shape of the haemoglobin molecule makes it difficult for the first O2 molecule to bind to one of the sites on it’s four polypetide chains as they are so closely united. This initailly creates a shallow curve

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12
Q

What happens when the first O2 molecule binds to haemoglobin?

A

The binding of the initial O2 molecule changes the quarternary structure of the haemoglobin molecule. This change makes it easier for the other sub units to bind to O2.

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13
Q

What is meant by the term positve co-operativity?

A

Binding of the second O2 molecule requires a smaller partial pressure than the first

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14
Q

What happens to haemoglobin after the third O2 molecule binds?

A

In theory it is easier fr haemoglobin to bind to the fourth O2 molecule, however with the majority of binding sites occupied it is less likely that an O2 molecule will bind to the empty one

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15
Q

How is the oxygen dissociation curve related to oxygen affinity?

A

The further left the curve is the greater the affinity of haemoglobin for O2.
The further right of the curve the lower the affinity of haemoglobin for O2.

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16
Q

What is the Bohr effect?

A

The greater the concentration of CO2, the more readily O2 is unloaded by haemoglobin

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17
Q

Why is the concentration of CO2 low at the gas exchange surface?

A

CO2 diffuses across the lungs and is excreted from the organism. Haemoglobins affinity for O2 is increased, and coupled with the high concentration of O2 in the lungs means O2 is readily loaded by haemoglobin. This reduces CO2 concentration

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18
Q

Why is the concentration of CO2 high in rapidly respiring tissues?

A

The affinity of haemoglobin for O2 is reduced, which couled with the low O2 concentrations means that O2 is readily unloaded from haemoglobin into the muscle cells. Increasing CO2 concentration.

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19
Q

Outline the process by which there is always enough O2 for respiring tissues?

A
  1. The higher the rate of respiration the more CO2 is produced.
  2. The more CO2 produced, the lower (more acidic) the PH.
  3. The lower PH leads to a greater change in the shape of haemoglobin, lowering it’s affinity for O2..
  4. The more readily O2 is unloaded, the more O2 is available for respiration.
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20
Q

Why do large organisms require a transport sysytem?

A

They have a low surface area to volume ratio and are very active

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21
Q

Name seven features of a transport system?

A
  1. A medium to tranport substances.
  2. A form of mass transport where the transport medium is moved in large distances
  3. A closed system of tubular vessels to contain the transport medium and form a branching network
  4. A mechanism for moving the transport medium within the vessels.
  5. A mechanism to maintain the mass flow movement in one direction
  6. A means of controlling the flow of transport to suit the dynamic needs of the organism
  7. A mechanism to support the mass flow, e.g. intercostal muscles
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22
Q

How is a pressure difference achieved between one part of a system and another?

A
  1. Animals use muscular contraction of the heart or muscles

2. Plants rely on passive processes such as the evaporation of water.

23
Q

Why do mammals have a double circularatory system?

A

When blood is passed through the lungs it has to pass through very small capillaries to achieve a large surface area for gas exchange
Pressure is reduced and if the blood were to be immediately passed through the body circulation would be very slow.

24
Q

Why do mammals have a high metabolism?

A

They have a high body temperature.

25
Q

How does the final part of mass transport achieved?

A

By diffusion between the blood vesses into cells as it takes place over a large surface area, across short distances, and over a steep concentration gradient

26
Q

What vessel joins the right ventricle of the heart to the lung capillaries?

A

Pulmonary artery

27
Q

What vessel carries oxygenated blood away from the heart?

A

Aorta

28
Q

What vessel carries deoxygenated blood away from the kidney?

A

Renal vein

29
Q

What is the first main vessel an O2 molecule reaches after being absorbed from the alveolus?

A

Pulmonary vein

30
Q

What vessel has the highest blood pressure?

A

Aorta

31
Q

What vessel takes deoxygenated blood to the right atrium?

A

Vena cava

32
Q

Describe the atrium?

A

Thin walled
Elastic
Stretches as it collects blood

33
Q

Describe the left ventricle?

A

Has a very thick muscular wall enabling it to create enough pressure to pump blood around the whole body (not lungs)

34
Q

Describe the right ventricle?

A

Thinner musular wall as pumps blood only to the lungs

35
Q

What are the two valves between the atrium and ventricles called? What is their function?

A

Left (bicuspid) and right (tricuspid), atrioventricular valves.
Prevent the backflow of blood into the atria when the ventricles contract.

36
Q

Describe the aorta?

A

Connected to the left ventricle and takes oxygenated to the body (not lungs)

37
Q

Describe the vena cava?

A

Connected to the right atrium and brings deoxygentated blood back from the bodies tissues

38
Q

Describe the pulmonary artery?

A

Connected to the right ventricle and carries deoxygentaed blood to the lungs where O2 is replenished and CO2 removed

39
Q

What causes a myocardial infarction?

A

A blockage in the coronary arteries which branch of the aorta leading to an area of the heart muscle being deprived of blood. The muscle cells therefore cannot carry out aerobic respiration and die

40
Q

Describe the pulmonary vein?

A

Connected to the left atrium and carries oxygenated blood back from the lungs.

41
Q

Describe diastole?

A

As the atria fill from the pulmonary vein and the vena cava the pressure builds. When the pressure is higher than in the ventricles, the atrioventricular valves open allowing blood to flow into the ventricles, this process is assisted by gravity. The atria and ventricles are both relaxed meaning the ventricular walls recoil and this reduces the pressure inside the ventricle. This means pressure is lower than in the atria and the aorta so their semi-lunar valves close.

42
Q

Describe atrial systole?

A

The contraction of the atrial walls along with the recoilng of the ventricular walls, forces the the remaining blood into the ventricles.

43
Q

Describe ventricular systole?

A

After a short delay to allow the ventrices to fill with blood their walls contact. This increases the blood pressure within them forcing the atrioventricular valves to shut preventing the backflow of blood into the atria. Once the pressure inside the ventricles exceeds that of the aorta and pulmonary artery blood is forced into them.

44
Q

State the role of valves in the cardivascular system?

A

Prevent the backflow of blood ensuring a uni directional flow of blood

45
Q

State the role of the role of the role of the semi-lunar valves?

A

In the aorta and the pulmonary artery to prevent the backflow of blood when pressure exceeds that of the ventricles.

46
Q

State the role of pocket valves?

A

Occur throughout the venous system in veins to ensure that when squeezed blood still flows towards the heart

47
Q

Describe the structure of valves?

A

Made of tough flexible fibrous tissue.
Cusp shaped
When pressure is greater on the convex side they move apart allowing blood to pass through.
When pressure is greater on the convex side blood collects within the bowls of the cusps pushing them together to form a tight fit preventing the passage of blood.

48
Q

How do you calculate cardiac output?

A

Heart rate multiplied by stroke volume.

49
Q

What is the basic layer structure of blood vessels?

A
  • Tough fibrous outer layer that resists inwards + outwards pressure changes
  • Muscle layer that can contract and so control the flow of blood
  • Elastic layer helping to maintain blood pressure by recoiling
  • Endothelium which is smooth to reduce friction and thin for diffusion
  • Lumen which is the central cavity
50
Q

How is the structure of arteries related to their function?

A
  • Thick muscle layer meaning smaller arteries can be constricted and dilated to control the volume of blood passing through them
  • Very thick elastic layer so BP can be kept high so blood can reach extremeties. Stretching and recoiling during the cardiac cycle helps to maintain high BP
  • Thick overall wall resisting the vessel bursting under ugh pressure
  • No valves as blood is constantly under high pressure
51
Q

How is the structure of arterioles related to their function?

A
  • Very thick muscle layer so it can contact allowing the constriction of the lumen
  • Thinner elastic layer as BP is lower than in arteries
52
Q

How is the structure of veins related to their function?

A
  • Thin muscle layer as blood is carried away from tissues so no need for constriction an dilation
  • Thin elastic layer as BP will not cause bursting or recoiling
  • Small thickness of wall as BP to low to cause bursting. Also allows them to be flattened aiding blood flow.
  • Pocket valves to prevent backflow of blood
53
Q

How is the structure fo capillaries related to their function?

A

Function= To exchange metabolic materials eg O2, CO2 and glucose between the blood and tissues

  • Extremely thin walls to reduce diffusion distance allowing rapid exchange.
  • Narrow diameter so can permeate tissues providing a short diffusion distance
  • Numerous and highly branched providing a large surface area for exchange
  • Narrow lumen so RBC’s are squeezed flat against the capillary wall reducing diffusion distance
  • Spaces between the endothelial cells allowing WBC’s to escape to deal with infections
54
Q

What is tissue fluid?

A
  • Solution provided to tissues containing glucose, amino acids, fatty acids, ions and oxygen
  • Collects waste materials e.g. CO2 from tissues

Biology AQA A-Level (18 decks)

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