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 Damage to gas exchange system

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

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 Effect on gas exchange system

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

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 tumour

Diseases of Gas Exchange system associated with smoking

• Lung Cancer• Bronchitis• Emphysema• COPD (chronic obstructive pulmonary disease)

Lung CancerSEM 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

Black deposits of tar in tissues Large cancerous tumour

Outside lung Inside lung

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

BronchitisInflammation 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 yellowish-gray 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

EmphysemaSEM 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 rateIncreases breathing rateConstricts arteriolesIncreases blood pressure

Nicotine causes constriction of the arterioles

Increases blood pressureReduces blood flow to extremitiesMay lead to necrosis of tissues-lack of O2 and glucoseIn 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 bloodWhen 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