Mass Transport Flashcards

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1
Q

Erythrocytes (Red Blood Cells)

A
  • Biconcave to increase surface area for diffusion of O₂
  • Flat and thin (1 cell thick) to allow for a short diffusion pathway
  • Large amount of haemoglobin to increase the rate of diffusion
  • No nucleus or organelles to maximise space for haemoglobin so more O₂ can be transported
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2
Q

Haemoglobin

A
  • Large globular proteins with a quaternary structure (made of 4 polypeptide chains)
  • Each chain has a haem group containing an iron ion (Fe⁴⁺) which gives haemoglobin its red colour
  • Each Hb molecule can bind with up to 4 O₂ molecules (O₂ binds to haem group)
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3
Q

Formation of Oxyhaemoglobin

A
  • In the lungs, O₂ diffuses from the alveoli to the capillaries and into the RBCs where it associates with haemoglobin and forms oxyhaemoglobin
  • Hb + 4O₂ ⇄ HbO₈
  • Haemoglobin + Oxygen ⇄ Oxyhaemoglobin
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4
Q

High Affinity Haemoglobin

A
  • Easily takes ups O₂
  • Releases O₂ less easily
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5
Q

Low Affinity Haemoglobin

A
  • Takes up O₂ less easily
  • Releases O₂ easily
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6
Q

Factors impacting O₂’s affinity for O₂

A
  • Partial Pressure of O₂
  • Partial Pressure of CO₂
  • Haemoglobin saturation
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7
Q

Where in the body are high affinity haemoglobin found?

A
  • In the lungs
  • Higher pO₂ which promotes O₂ loading
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8
Q

Where in the body are low affinity oxygen found?

A
  • In O₂ starved areas, e.g. the lungs
  • Lower pO₂ which promotes O₂ unloading
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9
Q

Co-Operative Binding

A
  • As each O₂ molecule binds to the haemoglobin, it changes the shape of the haemoglobin in a way that makes it easier for further O₂ molecules to bind
  • This is the case for the first 3 molecules of O₂
  • After the 3rd molecule, its harder for the 4th molecule to bind
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10
Q
A
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