Biology AS: F212: Smoking

Tar:

• settles on lining of alveoli - increases diffusion distance for oxygen entering blood and COD leaving blood
• can cause an allergic reaction if lieing on the surface
• causes smooth muscle to contract
• causes lumen to get smaller - resticts flow of air to alveoli
• stimulates goblet cells to enlarge and secrete more mucus - mucus thne gets trapped in air way - so bacteria and viruses cannot be removed

Smokers cough:

• attempt to move bacteria that is trapped in airway 
• smokers cough comes from irratation of airways by the mucus and bacteria plus the needed to clear airways 

If cough is constant:

• damages delicate lining of airways
• alveoli lining becomes damaged
• lining replaced by scar tissue - thicker and less flexible
• smooth muscle thickens - lumen narrows - air flow to alveoli is constantly restricted

Long term presence of bacteria and viruses in the mucus in the airways leads to:

• damages layer of epithelium 
• loss of elastic tissue in alveoli means that during exhalation alveolus wallas do not recoil and push air out 
• bronchioles collapse - traps air in alveoli 

Carcogenic compounds in cigareetes is the reason smoking can cause lung cancer:

• in tar
• enter the cells of lung tissue
• enter the nucleus of these cells - direct affect on genetic material
• mutations occur
• if mutation effects genes that control cell division then uncontrolled cell division may take place = lung cancer 

Lung cancer symptoms:

• contiual coughing
• shortness of breath
• pain in chest
• blood coughed up in septum

• inflammation to lining of airways
• damage to cilia
• overproduction of mucus
• leads to increased lung infection

Symptoms:

• irritation in lungs
• continual coughing
• coughing up mucus filled w/ bacteria and white blood cells 

• loss of elascitiy in alveoli
• alveoli can potentially burst
• more spaces in lungs - lungs have reduced surface area for gaseous exchnage

Symptoms:

• short of breath
• harder to exhale 
• breathing more shallow and rapid
• fatigue

• causes the addiction
• nicotine mimics the action of transmitter substances at the synapses between nerves - so nervous system feels more alert
• releases hormone adrenlate - heart rate, breathing rate increases
• reduces blood flow and oxygen delivering to the extremities
• makes platelets sticky - increase risk of blood clots 

• carbon monoxide combines with haemoglobin in red blood cells
• problem: carbon monoxidea can combine with haemoglobin much more readily than oxygen
• carboxyhaemoglobin formed
• reduces oxygen carrying capacity of the blood

1. carbon monoxide damages inner lining of arteries

2. white blood repair damage - encourage growth and deposit fatty substances (LDLs)

3. build up of atheromas under endothelium/inner lining of artery

4. atheroma eventually forms a plaque - stick out into lumen of artery

 5. artery wall less flexible and lumen size reduced 

• after atherosclerosis - lumen of coronary artery reduced
• reduces blood flow to the cardia muscle
• less oxygen flow to heart and less CO2 removed from heart

CHD can take 1 of 3 forms:

1. angina = severe pain in chest

2. heart attack/ myocardial infarction = death of part of the heart muscle 

3. heart failure - heart cannot sustain pumping due to blockage in coronary artery 

Stroke = death of part of the brain tissue - cuased by th eloss of blood flow to the part of the brain 

2 possible causes:

1. blood clot floating around in blood blocks an artery leading to part of the brain

2. artery leading to brain bursts