CIE A Level Biology (9700) 2019-2021

Revision Notes

9.2.2 The Effects of Nicotine & Carbon Monoxide

Nicotine & Carbon Monoxide Effects

  • Nicotine and carbon monoxide in cigarettes affect the ability of the cardiovascular system to function properly
  • Nicotine is the addictive component of cigarettes. It causes vasoconstriction, which is the narrowing of blood vessels
  • Vasoconstriction limits the flow of blood around the body, increases blood pressure and makes it harder for oxygen to reach all body cells
  • This lack of oxygen can force cells to respire anaerobically, creating lactic acid
  • Nicotine can also make platelets ‘sticky’ and they clump together, potentially forming a thrombosis (blood clot)

Carbon monoxide

  • Once inhaled, carbon monoxide in cigarettes binds to haemoglobin instead of oxygen
  • This is because chemically carbon monoxide has a much higher affinity for haemoglobin than oxygen
  • When this happens, oxygen cannot bind to haemoglobin and carboxyhaemoglobin (COHb) is formed instead of oxyhaemoglobin
  • This decreases the amount of oxygen delivered to cells for aerobic respiration and cells may have to respire anaerobically instead
  • This forces the heart to work harder to pump and deliver adequate oxygen, increasing heart rate and causing breathlessness
  • Carbon monoxide also promotes the release of free radicals, such as peroxides and superoxides
  • Carbon monoxide can also cause platelets and neutrophils to stick together, affecting the ability of white blood cells to fight infection

Worked example

The drug nicotine has a similar structure to acetylcholine. Suggest the effects on brain neurons of inhaling nicotine from a cigarette.

Nicotine will fit into membrane receptors and is not broken down by enzymes. This means that action potentials are generated for a long period of time.

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Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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