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a level biology: organisms exchange substances with the environment > mass transport in animals > Flashcards

mass transport in animals Flashcards

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1
Q

what is the structure of a haemoglobin?

A
  1. primary structure: sequence of amino acids in the polypeptide chain.
  2. secondary structure: polypeptide chains are coiled into a helix.
  3. tertiary structure: polypeptides folded into a specific shape to carry out their function.
  4. quaternary structure: polypeptides linked to make a spherical molecule
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2
Q

what is each polypeptide associated with in a haemoglobin?

A

haem group: contains an Fe2+ ion.

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3
Q

how many oxygen molecules can an Fe2+ combine with?

A

1, so 4 can be carried by a single haemoglobin.

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4
Q

what is the loading/ associating process?

A

haemoglobin binding with oxygen.
happens in the lungs.

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5
Q

what is the unloading/ dissociating process?

A

haemoglobin releases oxygen.
happens at the tissues.

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6
Q

what is high affinity?

A

haemoglobin take up oxygen more easily, but release it less easily.

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7
Q

what is low affinity?

A

haemoglobin take up oxygen less easily, but release it easily.

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8
Q

what is the role of haemoglobin?

A

to transport oxygen.

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9
Q

how are haemoglobin adapted to transport oxygen?

A
  1. readily associate with oxygen at the surface where gas exchange takes place.
  2. readily dissociate with oxygen at tissues.
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10
Q

how does haemoglobin change its affinity?

A

changes its shape in the presence of certain substances.

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11
Q

what is the oxygen dissociation curve?

A

the graph of the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen.

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12
Q

how can you explain the shape of the oxygen dissociation curve?

A
  1. the first oxygen is difficult to bind to because the polypeptide subunits are closely united - gradient is shallow initially.
  2. binding of the first oxygen molecule changes the quaternary structure so induces subunits to bind.
  3. second haemoglobin needs a smaller partial pressure to bind - gradient steepens.
  4. after the binding of the third molecule, it gets harder again because the majority of binding sites are occupied - gradient levels off.
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13
Q

what does it mean if the oxygen dissociation curve is further to the left?

A

greater affinity of haemoglobin for oxygen.

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14
Q

what does it mean if the oxygen dissociation curve is further to the right?

A

lower affinity of haemoglobin for oxygen.

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15
Q

what is the effect of carbon dioxide concentration on the affinity for oxygen?

A

haemoglobin have less affinity for oxygen.
oxygen is released.
Bohr effect.

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16
Q

what is the CO2 concentration at gas exchange surfaces?

A

low because it diffuses across the exchange surface and is excreted from the organism.
affinity for oxygen is increased.
oxygen dissociation curve shifts to the left.

17
Q

what is the CO2 concentration at respiring tissues?

A

high because the affinity for oxygen is reduced .
oxygen dissociation curve shifts to the right.

18
Q

how does the body ensure there is always efficient oxygen at respiring tissues?

A

higher rate of respiration -> more CO2 produced by tissues -> lower pH -> greater haemoglobin shape change -> oxygen dissociated more readily -> more oxygen available for respiration.

19
Q

what is the cardiac cycle?

A

the sequence of events taking place during one complete heartbeat.

20
Q

what is systole?

A

periods when the heart is contracting.

21
Q

what is diastole?

A

periods when the heart is relaxing

22
Q

what happens during passive filling of the ventricles?

A
  1. atria and ventricles are relaxed.
  2. AV valves are open, semi-lunar valves are closed.
    3.blood flows passively from the atria through the AV valves and into the ventricles.
23
Q

what happens during atrial systole?

A
  1. passive filling continues until the ventricles are 70% full.
  2. increased volume of blood in the ventricles forces AV valves closed.
  3. atria contract and blood is propelled into the ventricles.
24
Q

what happens during isometric ventricular contraction?

A
  1. both sets of valves are closed, atria and ventricles are relaxed.
  2. ventricles begin to contract but the muscles can’t change in length - isometric contraction.
  3. pressure in the ventricles builds up.
25
Q

what happens during ventricular ejection?

A

rising pressure exceeds the aorta and pulmonary arteries so semi-lunar valves open and the blood leaves the heart.

26
Q

what happens during ventricular relaxation?

A
  1. ventricles relax and semi-lunar valves close.
  2. pressure in ventricles becomes lower than atria so AV valves open.
  3. passive filling of ventricles begins and the cycle starts again.
27
Q

what is the conduction system?

A

specialised cardiac muscle cells that initiate each heartbeat.

28
Q

what is the conduction system made up of?

A

SA node
AV node
bundle of His
conduction fibres

29
Q

what does the SA node do?

A
  1. emits spontaneous electrical impulses that spread across the atria.
  2. when electrical impulses reach the border between the atria and ventricles they’re blocked by fibrous tissue.
  3. pass through the AV node which slows them down, allowing the atria to contract.
  4. stimulate atrial systole as they spread across the atria.
  5. impulses conducted along the bundle of His, which divide into fibres that spread through ventricular muscles.
  6. ventricular systole is triggered.
30
Q

what are the blood vessel walls composed of?

A

tunica externa
tunica media
tunica intima

31
Q

what is the role of the arteries?

A

pump blood out of the heart.
withstand the pressure of the blood.

32
Q

what types of tissue are in the arteries?

A

muscular and elastic

33
Q

why is there elastic tissue in the arteries?

A

to stretch and accommodate for the blood ejected from the heart.
recoil as it relaxes.

34
Q

what are arterioles?

A

composed of 3 layers and smaller than arteries.
control blood flow to different organs

35
Q

what is the role of veins?

A

transport blood from organs to the heart.

36
Q

what are the features of veins?

A

no elastic fibres
thin muscle walls

a level biology: organisms exchange substances with the environment (1 decks)

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