The Effects of Smoking
Describe the effects of smoking on the
mammalian gas exchange system, with
reference to the symptoms of
• chronic bronchitis
• emphysema (chronic obstructive pulmonary
disease or COPD)
• lung cancer
Constituents of cigarette smoke that
cause damage to health
Cigarette smoke contains over 4000 different
chemicals. The main problems are caused by :
• Tar, a mixture of substances including
carcinogens (chemicals that cause cancer)
• Nicotine
• Carbon Monoxide
Short Term Effects of Tar on Gas Exchange System
(NB: tar does not pass through lung tissue into blood stream)
Cause
Tar settles on lining of airways and
alveoli
Chemicals in tar causes an allergic
reaction
Tar paralyses or destroys cilia of
ciliated epithelium
Tar stimulates over-production of
mucus from goblet cells and mucus
glands
Mucus trapped and collects in
airways
Microbes trapped in airways
Damage to gas exchange system
Short Term Effects of Tar on Gas Exchange System
(NB: tar does not pass through lung tissue into blood stream)
Cause
Damage to gas exchange system
Tar settles on lining of airways and
alveoli
tar layer slows gas exchange by increasing
diffusion distance for gases
Chemicals in tar causes an allergic
reaction
smooth muscle in airway walls contracts.
Reduces lumen diameter, restricts flow of air in
and out of airways
Tar paralyses or destroys cilia of
ciliated epithelium
Cilia no longer move mucus out of airways
Tar stimulates over-production of
mucus from goblet cells and mucus
glands
Mucus collects in airways, bacteria and viruses
become trapped in mucus. Cilia unable to
move it.
Mucus trapped and collects in
airways
Can cause blockages in small bronchioles
preventing air flow in and out
Microbes trapped in airways
Likely to cause infection in lungs,
eg: pneumonia and influenza
Long Term Effects of Tar on Gas
Exchange System
Cause
Irritation of airways by mucus and microbes
Frequent coughing damages cells lining the
airways,
Frequent coughing thickens the smooth
muscle layer
Constant infections encourage more white
blood cells to pass into lung tissues
Damaged alveoli and bronchioles cannot
stretch and recoil properly
Deposition of tar which contains carcinogens
on lung tissue
Effect on gas exchange system
Long Term Effects of Tar on Gas
Exchange System
Cause
Effect on gas exchange system
Irritation of airways by mucus and microbes
leads to frequent and persistent coughing
Frequent coughing damages cells lining the
airways,
then damaged cells are replaced by thicker
less flexible scar tissue
Frequent coughing thickens the smooth
muscle layer
then the thicker muscle layer reduces the
lumen of the airway so air flow in and out is
restricted
Constant infections encourage more white
blood cells to pass into lung tissues
white blood cells produce elastase enzyme
which breaks down elastic tissue in alveoli
and bronchioles
Damaged alveoli and bronchioles cannot
stretch and recoil properly
so air is not pushed out of alveoli, alveoli
may burst due to coughing, bronchioles may
collapse
Deposition of tar which contains carcinogens
on lung tissue
carcinogens taken into nucleus of cells,
causes mutations to DNA. Mutation of genes
can cause uncontrolled cell division ie: a
Diseases of Gas Exchange system
associated with smoking
•
•
•
•
Lung Cancer
Bronchitis
Emphysema
COPD (chronic obstructive pulmonary disease)
Lung Cancer
SEM of a lung cancer cell.
Cancer cells divide rapidly in a chaotic,
uncontrolled manner.
They may clump to form tumours, which
invade and destroy surrounding
tissues.
Lung cancer is a common form of cancer,
frequently associated with smoking
tobacco. It often develops at the
entrance to the bronchi
It causes a persistent cough, shortness
of breath and chest pain. Blood may
be coughed up in sputum.
Cancer may spread to other areas of the
body.
Treatment includes surgical excision of
the affected areas of the lung, with
radiotherapy and chemotherapy.
Lung cancer
Outside lung
Black deposits of tar in tissues
Inside lung
Large cancerous tumour
Lung cancer
Signs and Symptoms
• Often no symptoms early on
• Later symptoms maybe:
• cough, shortness of breath, wheezing, chest
pain, and coughing up blood
Bronchitis
Bronchitis
Inflammation of the airway lining, damaged cilia, increased mucous production.
Persistent cough, mucus filled with microbes and white blood cells
Signs and symptoms of Bronchitis
• Cough
• Production of mucus
(sputum), either clear
or white or yellowishgray or green in color
• Shortness of breath,
made worse by mild
exertion
• Wheezing
•
•
•
•
Fatigue
Slight fever and chills
Chest discomfort
Frequent respiratory
infections (such as colds
or ‘flu) with a
worsening productive
cough
Emphysema
Emphysema
Damaged alveoli
Normal alveoli
Emphysema
SEM of human lung tissue affected by
emphysema.
Emphysema is a disease in which the alveoli
of the lung become enlarged and the
walls separating them are damaged.
This damage occurs as a result of elastase
enzyme breaking down the elastic fibres
which allow the alveoli to expand and
recoil. There is difficulty exhaling.
Surface area for gaseous exchange is
reduced, restricting oxygen uptake. This
may cause breathlessness, bluish skin,
and heart or respiratory failure.
Occurrence of emphysema is strongly
associated with smoking.
Treatment of emphysema is with drugs and
the cessation of smoking.
Emphysema signs and symptoms
• Shortness of breath,
shallow breathing
• Wheezing, difficulty
breathing out
• Fatigue, extreme
tiredness
• Heart failure
• Cyanosis / blue tinge
to skin
• High blood pressure
to lungs
• Enlarged right side of
heart
Learning Outcome
Describe the effects of
nicotine and carbon monoxide
in tobacco smoke on the
cardiovascular system
with reference to the course of events leading to
• atherosclerosis
• coronary heart disease
• strokes.
• Match the effect that CO and nicotine have on
the body to the damage that they cause
• Sort the cards into 6 pairs
Remember Nicotine and Carbon Monoxide enter the
lungs and pass through the lung surface into the blood
Effects
Consequences
Nicotine stimulates release of adrenaline
Adrenalin:
Increases heart rate
Increases breathing rate
Constricts arterioles
Increases blood pressure
Nicotine causes constriction of the
arterioles
Increases blood pressure
Reduces blood flow to extremities
May lead to necrosis of tissues-lack of O2 and glucose
In extreme cases may result in amputation
Nicotine makes platelets more sticky
Increases the risk of blood clot or thrombus forming
Nicotine mimics action of
neurotransmitters at synapses
Makes the smoker feel more alert
Carbon monoxide combines with
haemoglobin to form
carboxyhaemoglobin
Reduces the oxygen carrying capacity of blood
When exercising heart rate and breathing rate rise
more than normal
Carbon monoxide causes damage to
arterial endothelial linings
Damage to lining makes it more likely that plaques
develop
Development of Atheromas
(Atherosclerosis)
• Damage to the arterial endothelium by CO or hypertension
• Cholesterol, fatty deposits and cellular waste are deposited under the
damaged area in the wall, which is then repaired
• Inflammation at the site stimulates monocytes to infiltrate the area
• Monocytes differentiate into macrophages which ingest the cholesterol
and turn into “foam cells”. This is what forms the “plaque”
• These changes also stimulate smooth muscle cells to multiply and form a
“cap”
• The whole area increases in size and extends out into the lumen of the
artery restricting blood flow.
• The atheroma may finally break through the repaired endothelium again
and release some of the lumps of fatty deposit into the blood stream. This
can increase the likelihood of blockages in small arteries.
Development of Atheroma in arterial
walls (Atherosclerosis)
Reduction of arterial lumen by
atheroma
lumen
atheroma
• Watch real player video on atherosclerosis
Essay
Explain how Nicotine and
Carbon Monoxide contribute to the
occurrence of
Coronary Heart Disease and Strokes