Smoking

Cigarette smoke includes:

• Tar
• Carbon Monoxide
• Nicotine

Tar

• Settles on the lining of the airways and alveoli
  • This increases diffusion distance for oxygen entering the blood and carbon dioxide leaving the blood
• Tar can cause the smooth muscle in the walls of the airways to contract
  • This causes the lumen of the airway to get narrower which restricts the flow of air to the alveoli
• Tar paralyses or destorys the cilia on the surface of the airway, so they are unable to move the layer of mucus away
• Tar also stimulates the goblects cells to release more mucus and this mucus colelcts in the airways
• Bacteria trapped in the mucus is not removed so multiply and block bronchioles as well as causing the lungs to be more susceptiable to infection

• Smoker's cough is an attempt to shift the bacteria mucus that collects in the lungs
  • It results from irritation of the airways, as well as from the need to clear the airways in order to get air down into the alveoli
• The cough damages the delicate lining of the airways and alveoli
  • The lining gets replaced by scar tissue which is thicker and less flexible 
  • Layer of smooth muscle in the all of the bronchioles thickens which reduces the lumen of the airway and the flow of air is permanetly restricted
• Alveoli and bronchioles loses it elastic tissue

• Carcinogenic compounds cause cancer - found in tar
• They enter the cells of the lung tissues
• They enter the nucleus and have a direct effect upon the genetic material
• Any changes to the genetic material is called a mutation
• if the mutations affect the genes that control cell division, then uncontrolled cell division takes place - this is cancer
• The tumour grows uncontrollably blocking air flow to areas of the lungs which decreases gas exchange and leads to shortness of breath
• The tumour uses lots of nutrients and energy to grow, which causes weight loss

• The inflammation of the lining of the airways 
• Accompanied by the damage to the cilia and the overproduction of mucus, so that mucus collects in the lungs - caused by cigarette smoke
• Symptoms are:
  • Irritation in the lungs 
  • Continual coughing
  • Coughing up mucus that is often filled with bacteria and white blood cells
  • Lung infection 

• the loss of elasticity in the alveoli, which causes the alveoli to burst 
• The lungs have reduced surface area as larger air spaces are formed
  • this decreases the rate of gaseous exchange
• Symptoms:
  • Shortness of breath
  • Increased breathing rate as they try to increase the amount of air reaching their lungs 
  • The blood is less well oxygenated and fatigue occurs 

• Nictotine
  • Increases the heart rate
  • Increases breathing rate
  • Constriction of arterioles - this raises the blood pressure 
  • Makes the platelets sticky - increases the of bloodclots forming
• Carbon Monoxide
  • Enters the red blood cells and combines with haemoglboin
  • Carboxyhaemoglobin reduces the oxugen carrying capacity of the blood
  • Damages the lining of the arteries 

• Carbon monoxide can damage the inner lining (endothelium) of the arteries
• If the person also has high blood pressure, this will add to such damage
• The damage is repaired by the action of white blood cells 
• This encourages the growth of smooth muscle and deposition of fatty substances
• High blood pressure also increases the deposition of cholesterol - atheromas 
  • This process of deposition is called atherosclerosis - the hardening of arteries due to the formation of atheromas 
• Build-up of atheromas occurs under the endothelium, in the wall of the artery 
  • Atheroma forms plaque which reduces the size of the lumen which reduces blood flow 
• Symptoms:
• • High blood pressure
  • Hypertension 

• When the coronary arteries have lots of atheromas in them. This restricts blood flow to the heart
• The lumen of the coronary artery is narrowed by plaques, this reduces the blood flow to the heart muscles, which receive less oxygen for respiration 
• This can cause:
  • Angina - severe pain in chest
  • Heart attack 
  • Heart failiure
• Smoking increass the risk of CHD bc carbon monoxide irreversibly combines with haemoglobin which reduces the amount of oxygen transported in the blood
• Nicotine in cigarette smoke makes platelets sticky which increases the chance of blood clots forming - if this happens in the coronary arteries then it could cause a heart attack
• Presence of atheromas also increases the risk of blood clots forming 
• Symptoms
  • difficult to exercise
  • Shortness of breath

• Rapid loss of brain function due to a disruption in the blood supply to the brain
• Can be caused by a blood clot in an artery leading to the brain, which reduces the amount of blood and oxygen that can reach the brain
• Nicotine increases the risk of stroke because it increases the risk of clots forming
• Carbon monoxide also increases the risk of stroke because it reduces the amount of oxygen avaliable to the brain by combining with haemoglobin 
• Symptoms
  • numbness of face
  • Difficulty to speak
  • Difficulty to see
  • Difficulty to walk
  • Servere headache

CHD is a multifactoral disease. The risk factors are:

• Age
• Sex
• Cigarette smoking
• Obesity
• High blood pressure
• High blood cholesterol concerntration
• Lack of exercise
• Diet high in saturated fat
• A high salt intake
• Absence of polyunsaturated fats
• Genetic factors
• Diabetes
• Stress