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BIOL10002 > 22. Respiration > Flashcards

22. Respiration Flashcards

1
Q

What is ventilation?

A

Movement of the medium (air, water) over a gas exchange surfaces

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2
Q

What does respiration refer to?

A
  • Oxidation of the end products of glycolysis (by 02 in eukaryotes)
  • Breathing or physiological respiration
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3
Q

Is it better to breathe from oxygen in water or air?

A
  • There is 21% O2 in the atmosphere
  • Atmospheric pressure changes with altitude, higher the altitude the lower the pressure
  • Fewer molecules of oxygen/ litre air
  • In still water water is not in contact with air and contains less O2
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4
Q

What is hypoxia?

A
  • Low O2 in blood or environment
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5
Q

What is anoxia?

A
  • Complete absence of O2 in the environment
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6
Q

What is hypercapnia?

A

Excessively high CO2 levels in blood

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7
Q

What is partial pressure in reference to gas?

A

Component of total pressure contributed by a single (free) gas within a mixture of gases

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8
Q

Why is air a better respiratory medium than water?

A
  • Oxygen diffuses 8000 times more rapidly in air than in water
  • To move medium over a gas exchange site, more energy is required to mover water than air (water is 800x denser and 50x more viscous than air)
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9
Q

How does respiration occur in small animals?

A
  • Small animals can take up 02 directly from the environment through the body surface
  • Simple diffusion distributes 02 throughout the body, into cells and throughout their cytoplasm
  • No specialised respiratory structures required
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10
Q

When is diffusional transport of 02 effective?

A

Diffusional transport of 02 is only efficient if distance is 1mm at most

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11
Q

What are the greater demands for the respiratory system in larger more complex animals?

A
  • Higher cellular metabolic rate
  • Reduction in total surface area available for gas exchange
  • Large, multicellular organisms are too large for diffusion

Thus both aquatic and terrestrial animals have evolved respiratory systems with a large surface area to maintain adequate respiratory supply of oxygen to their tissues

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12
Q

What is Fick’s law?

A

Rate of gas exchange = (surface area x concentration gradient x diffusion coefficient)/diffusion distance

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13
Q

How is gas exchange maximised (based on the equation?

A
  • Increase surface area
  • Increase pressure difference
  • decrease diffusion distance
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14
Q

If terrestrial animals breath air then why does solubility of gases matter?

A
  • Matters because it is moist within the lungs so gases must dissolve through a layer of fluid to get into the lungs, and must stay dissolved when they are in the blood
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15
Q

What characteristics does an exchange site have?

A
  • A large surface area
  • Small diffusion distance (i.e thin epithelium/endothelium) between the respiratory medium and the blood or blood and tissues
  • A highly vascularised respiratory surface
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16
Q

Where do respiratory gases diffuse?

A

Across the exchange site (the respiratory epithelium and capillary endothelium)

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17
Q

How do you increase transport of O2 to tissues?

A

High surface area to volume ratio, ensure surfaces are thin and highly vascularised with lots of blood vessels

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18
Q

What is the purpose of a ventilation system?

A
  • It is to keep a constant supply to medium moving across the respiratory exchange site
  • Improves rate of gas exchange
  • Ensures that fresh supplies of O2 rich medium are supplies to the exchange surface
19
Q

What is the structure of the ventilation system in fish?

A

Mouth and operculum allow unidirection flow of water across gills

20
Q

What is the structure of the ventilation system in frogs?

A

Buccal cavity (2 phases of lung ventilation, tidal flow of air)

21
Q

What is the purpose of air sacs?

A

System for two cycles of inhalation and exhalation (unidirectional air flow)

22
Q

What is the purpose of the internal transport (circulatory system)?

A
  • It moves the dissolved O2 from the exchange site to respiring tissues
  • Also transports CO2 away from the metabolising tissues
23
Q

Why is the internal transport (circulatory) system essential?

A

Because diffusion is exceedingly slow over even moderate distances.

24
Q

What is the purpose of the circulatory system?

A

The heart acts as a pump to increase the movement of blood around the body

25
Q

How is the oxygen carrying capacity of blood increased?

A

By respiratory pigments (blood pigments)

26
Q

What are respiratory pigments?

A
  • Complexes of proteins and metal ions

- Have a characteristic colour that changes when it binds O2

27
Q

What is the difference between haemoglobin and haemocyanin?

A
  • Haemoglobin is dark and goes bright red when oxygenated

- Haemocyanin is colourless and goes blue when oxygenated

28
Q

How do respiratory pigments help oxygen bind?

A
  • O2 binds reversible to a metal ion associated with the protein chain of the respiratory pigment
29
Q

What is haemoglobin?

A

The main vertebrate respiratory pigment
- Each heme group can combine with one O2 molecule
There are 4 heme units = 4 x oxygen molecules per b

30
Q

When does sickle cell anaemia occur?

A
  • When an abnormal form of haemoglobin (HbS) is produced)

- HbS molecules clump together making red blood cells sticky and causing them to form into a curved sickle shape

31
Q

What is the implication of sickle cell anaemia?

A
  • Sickle cells can clog blood vessels and deprive the body’s tissues and organs of oxygen
  • Anaemia is when the body’s number of red blood cells (or amount of haemoglobin) falls below normal
  • Anaemic people often feel weak and tire more easily
32
Q

What is positive cooperatively?

A

Binding of the first oxygen molecule increases the binding affinity of subsequent O2

33
Q

What happens if there is a high pressure of oxygen in the blood?

A

A large amount of oxygen is bound to Hb

34
Q

What happens if there is a low pressure of oxygen in the blood?

A

Only a small amount of O2 is bound to Hb

35
Q

How does the affinity of respiratory pigments for O2 depend on different factors?

A
  • Type of respiratory pigment, eg myoglobin, Llama haemoglobin
  • pH of blood circulating through active tissues has a lower pH and H+ ions bind to the haemoglobin molecule in place of O2, lowering the affinity for O2 (the Bohr effect)
  • BPG lowers the affinity for O2
36
Q

What is 2,3-bisphosphoglyceric acid (BPG)?

A
  • Mammalian glycolysis metabolite found in RBCs
37
Q

How does BPG interact with Hb?

A

Reversibly combines with partly deoxygenated Hb and LOWERS its affinity for O2, thus O2 releases the remaining oxygen (O2 binding curve shifts right)

38
Q

How does high altitude affect BPG?

A
  • Level of BPG in RBCs increases at high altitude or with increased exercise
  • Helps Hb deliver more O2 to tissues where it is most needed
  • 2,3 BPG lost during blood storage
39
Q

How does respiratory pigment in muscle cells affect oxygen binding?

A
  • Muscle cells have the own O2 binding molecule (myoglobin)
  • It has a higher affinity than Hb for O2
  • Binds O2 at Pressure of O2 values much lower than HB
  • Provides an O2 reserve in muscles
40
Q

How many subunits does myoglobin have?

A

It is monomeric, only holds one oxygen

41
Q

What are the three ways in which carbon dioxide is transported in the blood?

A
  • 10% dissolved in plasma
  • 30% reversibly bound to Hb (carbaminohaemoglobin)
  • 60% are bicarbonate
42
Q

What is the carbon equation that occurs inside RBCs?

A

CO2 + H2O—> H2CO3 —> H+ + HCO3-

43
Q

How does Carbon dioxide conversion in the blood affect the equation?

A

Converting CO2 to H2CO3 decreases the pressure of CO2 in the blood - causing more CO2 to diffuse out of the tissues

44
Q

What are the two ways in which carbon dioxide is transported in the blood?

A
  1. Chloride/bicarbonate exchange (‘chloride shift’)
  2. H+ buffering by haemoglobin (Hb + H+ = HHb)

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BIOL10002 (28 decks)

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