Biology

Short Term Effects - Tar Build up

• Increases the diffusion distance for oxygen to diffuse into the blood.
• The tar may cause an allergic reaction causing the smooth muscle to contract, meaning airflow is restricted. 
• Cilia is paralysed
• Goblet Cells Stimulated, this increases the amount of mucus which is deposited on the airways.
• Trapped bacteria and viruses are not removed, leading to blocked bronchioles. 

Other Effects

• Smoker's cough: in an attempt to remove mucus on the airways, a cough results in damage of the lining of the airways/alveoli. This lining is replaced by scar tissue which is less flexible and thicker. The layer of smooth muscle in the bronchiole walls becomes thicker, so airway is permanently damaged. 
• Prone to frequent infections: Due to the bacteria and viruses in the mucus will begin to inflame in the lining of the airways. This damages the layer of epithelium. White Blood Cells are attracted to this area to try to fight the infection, they release enzymes which digest part of the lining of the lungs in order to pass through air spaces.

Lung Cancer

• Benzopyrene is a carciogenic compound found in the tar that lines airways. 
• The compounds enter the nucleus of cells and damages the genetic material. 
• When the genetic material becomes mutated, the control of cell division is affected. This causes uncontrolled cell division to take place (cancer). 

Symptoms

• Continual coughing
• Shortness of breath
• Chest pains
• Blood stained sputum (spit)

Chronic Bronchitis

• Inflammation of the lining of the airways.
• Accompanied by damage to cilia and over production of mucus.

Symptoms

• Irritation of the lungs
• Constant coughing
• Coughing up mucus which contains bacteria/white blood cells

Emphysema

• Loss of elasticity in alveoli causing alveoli to burst
• Lungs have a reduced surface area for gaseous exchange due to large air spaces that are formed. 

Symptoms

• Shortness of breath
• Difficulty exhaling
• Shallow, rapid breathing
• Fatigue as blood is not very well oxygenated

Nicotine

• Very addictive
• Mimics the neurotransmitter which makes the smoker more alert.
• Releases adrenaline 
• Restricts the arterioles
• Makes platelets more sticky increasing chance of blood clots

Carbon Monoxide

• Enters red blood cells and combines with haemoglobin to form carboxyhaemoglobin
• This carboxyhaemoglobin leaves less space for oxyhaemoglobin to form.
• So during exercise, the body detects the low level of oxygen which increases the heart rate. 

Artheroclerosis

• Carbon Monoxide can cause damage to the endothelium of arteries.
• High Blood Pressure increases the chance of damage.
• Phagocytes encourage repair of the smooth muscle and the deposition of fatty substances (Cholesterol) 
• This deposition is called atheromas

• The build up of atheromas under the endothelium of the artery wall
• Plaque is formed which sticks out into the lumen, this causes the artery wall to become much rougher and less flexible. 
• Lumen is narrower therefore blood flow is reduced

Thrombosis

• Blood clot caused by the plaque being rough.
• If the membrane that covers the plaque get damaged, the red blood cells stick to the fatty deposits. 
• This blood clost is known as thrombus.

• A clot in the artery may stop blood flow from the heart to muscles.
• If a clot if broken off and carried away, it may reach a narrow artery and block it. 

Coronary Heart Disease

• Coronary arteries carry blood to the heart.
• They brand off the aorta close to the heart, they carry blood at high pressure. Therefore, these arteries are prone to damage and artherosclerosis. 
• When the lumen is narrowed by plaques, blood flow to the heart muscles is reduced, this means there is:
• Less oxygen for respiration
• Can lead to Coronary Heart Disease

1) Angina: Severe pain in chest that can extend into neck and arms

2) Heart Attack/myocaridial infraction: When part of the muscle in the heart dies

3) Heart Failure: Heart muscle cannot sustain the pumping action, therefore, it fails. 

Stroke

• When part of the brain tissue dies
• Caused by blood flow to the brain
• Caused by:

1) Thrombus floating around blocked arteries to brain

2) Artery leading to part of the brain bursts (haemorrhage)

Symptoms of Stroke:

• Sudden numbess in the face, arm of leg
• Sudden confusion in speaking/understanding
• Sudden difficulty with sight in one or both eyes
• Sudden trouble with walking
• Sudden severe headache with no known cause

Cardiovascular Diseases

• Arteriosclerosis: when the artery walls become harder due to the deposition of minerals e.g calcium, in the walls/artheromas. 

• Coronary Heart Disease: When the heart muscle has insufficient amounts of oxygen for aerobic respiration due to the atheroma narrowing the lumen which reduces blood flow. This means the cardiac muscle cannot pump strongly. 

Risk Factors

Risk Factors are factors that increase the chance/risk of a person developing a disease.

• Age 
• Sex
• High Blood Pressure
• Smoking
• Obesity
• High Blood Cholesterol Concentration
• Physical Inactivity
• High level of animal fats in diet
• High salt intake
• Absence of healthy fats
• Absence of antioxidants, e.g vitamins
• Genetic factors
• Diabetes
• Stress