Tar
- Tar coats the airways and alveoli
- it can cause allergic reactions which narrows the airways
- it also destroys the cilia on the surface
- mucus cannot be moved
- tar stimulates production of extra mucus
- bacteria get stuck in the mucus and multiply in the airways
- the smoke has an increased risk of infection
- chronic bronchitis
- this is the disease caused by the inflammation of the airways
- accompanied by mucus collecting in the lungs
- symptoms
- irritation
- continual coughing
- coughing up mucus
- risk of lung infection
- long term effects
- frequent infections damages the lining of lungs
- white blood cells are attracted
- have to make their way from blood to airways
- use enzymes to dissolve their way through
- elastase enzyme dissolved the elastic tissue
- airways no longer recoil properly
- bronchioles collapse trapping air
- alveoli burst due to pressure of trapped air
- Emphysema
- disease caused by alveoli bursting
- lungs have less surface area
- so can do less gas exchange
- healthy lungs contains large quantities of elastic tissue, mostly made up of the protein elastin.
- this tissue stretches when we breathe and in and springs back when we breathe out.
- in emphysematous lungs, the elastin has become permanently stretched and the lungs no longer able to force out all the air from the alveoli
- the surface area of the alveoli is reduced and they sometimes burst
- as a result, little if any exchange of gases can take place across the stretched and damaged air sacs.
- symptoms
- shortness of breath - results from difficulty in exhaling air due to the loss of elasticity in the lungs
- if the lungs cannot be empties much of their air, then it is difficult to inhale fresh air containing oxygen so patient feels breathless
- the smaller the alveolar surface area leads to reduce levels of oxygen in the blood and so patient tries to increase oxygen supply by breathing more rapidly
- chronic coughs - consequence of lung damage and the body's effort to remove the damaged tissue and mucus that cannot be removed naturally because the cilia on the bronchi and bronchioles has been destroyed
- bluish skin colouration is due to low levels of O2 in the blood as a result of poor gas diffusion in the lungs
- Asthma
- common allergen which can trigger an asthma attack: pollen, dust mites, mould, pet dander
- asthma is an example of localised allergic reaction
- it can also be triggered or made worse by a range of factors, including air pollutants e.g. sulphur dioxide) exercise, cold air, infection, anxiety and stress.
- one or more of these allergens causes white blood cells on the lining of the bronchi and bronchioles to release a chemical called histamine
- effects of histamine - the lining of these airways become inflamed
- the cells of the epithelial lining secret larger quantities of mucus and enter the airways
- the muscle surrounding the bronchioles contracts and so constrict the airways.
- symptoms:
- difficulty in breathing - due to constriction of bronchi and bronchioles, their inflamed linings and the additional mucus and fluid within them
- a wheezing sound when breathing is caused by air passing through the very constricted bronchi and bronchioles
- a tight feeling in chest - consequence of not being able to ventilate the lungs adequately because of constricted bronchi and bronchioles
- coughing - reflex response to obstructed bronchi and bronchiole in effort to clear them
Chronic obstructive pulmonary disease
- combination of diseases including emphysema, chronic bronchitis and asthma
Lung Cancer
- cancers are caused carcinogens
- cigarette smoke contains many carcinogens
- carcinogens are present in tar
- they enter the cells of the lungg tissue
- they mutate the DNA in their nuclei
- if the gene for the cell division is mutate then uncontrolled cell division takes place - this is cancer
- lung cancer can take up 20-30 years to develop to a size to cause problems
- symptoms
- coughing up blood
- persistent cough
- weight loss
- shortness of breath
- chest pains
- Nicotine and Carbon monoxide
- these two chemicals can be absorbed in the lungs and enter the blood
- here they cause cardiovascular disease
- Nicotine
- causes addiction
- causes release of adrenaline
- thus increased heart and breathing rate
- increased force of contraction of the heart
- constriction of arterioles
- hypertension
- increases stickiness of platelets
- chance of thrombus (clotting)
- increased blood cholesterol and LDLs
- Carbon monoxide
- combine with haemoglobin
- forms carboxyhaemoglobin
- haemoglobin has higher affinity for CO than O2
- this is irreversible
- reduces O2 carrying ability of haemoglobin
- decrease in oxygen transported
- tissues starved of oxygen
- also damages lining areteries
Cardiovascular Disease
- atherosclerosis
- nicotine and CO damages artery walls
- hypertension contributes to the damage
- this attracts phagocytes to repair the damage
- these encourage the growth of smooth muscles and deposition of fatty substances
- fatty deposits are laid down when repaired including cholesterol
- these atheromas form plaques
- these narrow artery
- also make it rougher
- this reduced blood flow
- thrombosis
- blood flows slower past plaques
- combined with stickier platelets from nicotine - blood clots can form
- these block narrow arteries
- this may result in formation of blood cot, or thrombus, in a condition aka thrombosis
- this thrombus may block the blood vessel, reducing or preventing the supply of blood to tissues beyond it
- the region of tissue deprived of blood often dies as a result of the lack of oxygen glucos and other nutrients blood normally provides
- embolism is when the thrombus is carried from its place of origin and blocks another artery
- coronary heart disease
- when the atherosclerosis occurs in the coronary arteries and reduces/stop oxygen supply to the cardiac muscle for respiration
- Angina: severe chest pain due to lack of oxygen
- Heart attack: death of part of the heart muscle due to a blockage of artery
- Heart failure: heart stops pumping due to lack of oxygen by a blockage of major coronary artery
- Risk factors
- age - older
- sex - male
- diet high in saturated fats causes more LDLs
- plaque formation
- blood cholesterol
- high salt intake
- hypertension
- low fibre
- obesity
- heavy alcohol consumption
- and more
- stroke
- death of part of the brain
- due to blood clot forming in artery supplying brain
- artery supplying brain bursts (aneurysm)
- aneurysm
- atheromas that lead to the formation of a thrombus also weaken artery walls
- these weakened points swell to form a balloon-like blood filled structure - aneurysm
- frequently burst leasing to haemorrhage and therefore loss of blood to the region of the body served by that artery
- a brain aneurysm is know as a stroke
Cardiovascular diseases
- great cause of premature death
- CHD and stroke often result from atherosclerosis
- this can start in adolsescence
Treatment
- is expensive
- long term drug treatment to reduce blood pressure and cholesterol
- surgery
- therefore reduction in atherosclerosis through the reduction of risk factors is important
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