Gas Exchange And Smoking

Question 1

What is smoker’s cough?

Answer 1

1. Tar in cigarette smoke stimulates goblet cells and mucous glands to enlarge and secrete more mucus
2. Tar also inhibits the cleaning action of collated epithelium that lines the airways
3. It destroys many cilia and weakens and sweeping action of those that remain
4. As a result mucus accumulates in the bronchioles and the smallest of these become obstructed
5. As mucus is not moved or at best only moved slowly, dirt, bacteria and viruses collect and block the bronchioles
6. This stimulates ‘smokers cough’ which is an attempt to move the mucus up the airways
   - With time, the damaged epithelial are replaced by scar tissue and the smooth muscle surrounding the bronchioles and bronchi becomes thicker
   - This thickening if the airways causes them to narrow and makes it difficult to breathe

Question 2

What is chronic bronchitis?

Answer 2

1. Infections such as pneumonia easily develop in the accumulated mucus
2. When there is an infection in the lungs, the linings become inflamed and this further narrows the airways
3. The damage and obstruction of the airways is chronic bronchitis
4. Sufferers have a severe cough, producing large quantities phlegm, which is a mixture of mucus, bacteria and some white blood cells

Question 3

What is emphysema?

Answer 3

1. The inflammation do the constantly infected lungs causes phagocytes to leave the blood and line the airways
2. To reach the king of the lungs from capillaries, phagocytes release the protein digesting enzyme elastase
3. The enzyme destroys elastin in the walls of the alveoli, so making a pathway for the phagocytes to reach the surface and remove bacteria
4. Elastin is responsible for the recoil of the alveoli when we breathe out
5. With much smaller quantities of elastin in the alveolar walls, the alveoli do not stretch and recoil when breathing in and out
6. As a result the bronchioles collapse during expiration trapping air in the alveoli which often burst. Large spaces appear where the alveoli have burst and this reduces the surface area for gas exchange; the number of cpillaries also decreases, so less oxygen is absorbed into the blood
7. This condition is called emphysema
8. The number of
   Nucleotides and bases going into wrong places
   -Random, if mutation happens which controls cell division
   -Oncogenes
   -Chance wrong nucleotide put in, new copy of DNA so new cell so changed sequence of DNA

Question 4

What does the loss of elastin affect?

Answer 4

1. It make it difficult to move air out of the lungs

Question 5

What is the human gas exchange system adapted to do?

Answer 5

1. Clean and warm the air that enters during breathing
2. Maximise the surface area for diffusion of oxygen and carbon dioxide between the blood and atmosphere
3. Minimise the distance for this diffusion
4. Maintain adequate gradients for this diffusion

Question 6

Where are the lungs located in the body?

Answer 6

1. The lungs are in the thoracic cavity surrounded by the pleural membranes
2. These enclose and alright space which contains a small quantity of fluid to allow friction-free movement as the lungs are ventilated by the movement of the diaphragm and ribs

Question 7

What is the function of the cartilage? Where is it found?

Answer 7

1. Cartilage is in the trachea (regular arrangement of C-shaped rings) and bronchus (irregular blocks)
2. The cartilage in these areas keeps these areas open and air resistance low and prevents them from collapsing of bursting as the air pressure changes during breathing

Question 8

What is the function of the cilia? Where is it found?

Answer 8

1. Trachea, bronchus, terminal bronchiole, respiratory bronchiole (a few)
2. Carries mucus towards mouth to get rid of

Question 9

What is the function of goblet cells? Where are they found?

Answer 9

1. Trachea and bronchus
2. Produces mucus, and the upper part one each goblet cell is swollen with mucin droplets which have been scripted by the cell and the rest of it contains the nucleus which is quite slender like the stem of a goblet

Question 10

What is the function of the mucous glands? Where are they found?

Answer 10

1. Mucus is also made by mucous glands beneath the epithelium

Question 11

What is the function of the smooth muscle? Where is it found?

Answer 11

1. Trachea, bronchus and terminal bronchiole
2. Bronchioles are surrounded by smooth muscle, which can contract or relax to adjust the diameter of these tiny airways
3. During exercise the muscles relax to allow a greater flow of air to the alveoli
4. The absence of cartilage makes these adjustments possible

Question 12

What is the function of the elastic fibres?

Answer 12

1. Alveolar walls contain elastic fibres which stretch during inspiration and recoil during expiration to help force out air
2. This elasticity allows alveoli to expand according to the volume of air breathed in
   - When the alveoli are funny expanded during exercise, the surface area available for diffusion increases, and the air is expelled efficiently when the elastic fibres recoil

Question 13

How are the alveoli adapted for gas exchange?

Answer 13

1. Elastic fibres
2. Extremely thin walls, consisting of a single layer of squamous epithelial cells
3. They are pressed closely against blood capillaries with also very thin walls also diffusion is very effect as the distance is very small

Question 14

Why does the air breathed in need to be warmed?

Answer 14

1. Air is warmed to body temperature and moisten by evaporation from the lining
2. This protects the delicate surfaces inside the lungs for desiccation
   - Particles of suspended matter carried in the air are caught on the hairs indie the nose and the mucus lining the nasal passages and other airways

Question 15

Describe the process of gas exchange between air in the alveoli and the blood?

Answer 15

1. Breathing brings supplies of fresh air into the lungs with a relatively high oxygen concentration and a relatively low carbon dioxide concentration
2. Blood is brought to the lungs with a lower oxygen concentration and a higher carbon dioxide concentration
   than the air in the alveoli
3. Oxygen therefore diffuses down its concentration gradient form the air in the alveoli to the blood, and carbon dioxide diffuses downs its concentration gradient in the opposite direction
4. The blood is constantly flowing through and out of the lungs, so, as the oxygenated blood leaves, more deoxygenated blood enters to maintain the concentration gradient with each new breath

Question 16

What are the main components of cigarette smoke which pose a threat to human health?

Answer 16

1. Tar, which contains carcinogens (cacner-causing compounds which cause mutations in the genes that control cell division), this is a mixture of compounds that settles on the lining of the airways in the lungs and stimulates a series of changes that may lead to obstructive lung diseases and lung cancer
2. Carbon monoxide
3. Nicotine

Question 17

What are some forms of chronic obstructive pulmonary diseases (COPD)?

Answer 17

Asthma, chronic bronchitis and emphysema

Question 18

How does lung cancer relate to smoking?

Answer 18

1. The carcinogens in tobacco smoke react directly pr via breakdown products with DNA in epithelial cells to produce mutations which are the first in a series of changes that leads to the development of a tumour
2. As cancer develops it spreads through the bronchial epithelium and enters the lymphatic tissues in the lung
3. Cells may break away and spread to other organs so that secondary tumours become established (a malignant tumour)

Question 19

Why is it hard to diagnose lung cancer?

Answer 19

1. Lung cancer takes about 20-30 years to develop and most of the growth of the tumour occurs before there are any symptoms (most common is coughing up blood as a result of tissue damage)
2. By the time lung cancers are discovered, they are well advanced and treatment involves surgery, radiotherapy and chemotherapy

Question 20

How are tumours in the lung detected?

Answer 20

1. Bronchoscopy, using an endoscope to allow a direct view of the lining of the bronchi
2. Chest X-ray
3. CT scan

Question 21

How does nicotine short term effect the cardiovascular system?

Answer 21

1. It is the drug in tobacco and is absorbed very readily by the blood and travels to the brain
2. It stimulates the nervous system to reduced the diameter of the arterioles and to release the hormone adrenaline form the adrenal glands
3. As a result, heart rate and blood pressure increase and there is a decrease in blood supply to the extremities of the body, such as hands and feet reducing their supply of oxygen
4. Nicotine also increase the risk of blood clotting
5. Highly addiction and influence reward centres in the brain as it stimulates nerve endings in the brain to relate the transmitter substance dopamine, which is associated with reinforcing pleasurable experiences

Question 22

What is the short term effect of carbon monoxide on the cardiovascular system?

Answer 22

1. Binds with haemoglobin to form stable compound carboxyghaemoglnin and so haemoglobin not fully oxygenated
2. The quantity of oxygen transported in the blood may be 5-10% less in a smoker than in a non-smoker
3. Less oxygen is supplied to the heart muscle, putting a strain on it especially when the heart rate increases during exercise
4. Carbon monoxide may also damage the lining of the arteries

Question 23

What are the long term effects of carbon monoxide?

Answer 23

• These short term effects are readily reversible for people who have not smoked for very long but long term smokers put the health of their cardiovascular system at risk
  1. Damage to the walls of the arteries may lead to the build up of fatty tissue and the reduction of blood flow
  2. This causes damage to the cardiovascular site and increases the risk of coronary heart disease (CHD) and stroke

Question 24

Explain how uncontrolled cell division can result in cancer

Answer 24

1. Mutation initiating uncontrolled mitosis
2. Proof-oncogenes convert to oncogenes
3. Cell division by mitosis
4. Formtation fo tumour
5. No response to signals to control mitosis
6. No apoptosis
7. Immune system does not recognise the cells as foreign and desired then
8. Metastasis

Question 25

Describe the experimental evidence that shows that smoking causes lung cancer

Answer 25

1. Tar painted on skin of mice leads to development of cancerous tumour
2. Dogs smoked (plain) cigarettes cancer
3. Dogs smoked filtertilped cigarettes not develop cancer
4. Control group who did not smoke did not develop cancer