Chapter 9: gas exchange and smoking

Question 1

function of cartilage

Answer 1

• keep the trachea and bronchi open and air resistance low

- prevent them from collapsing or bursting as the air pressure changes during breathing

Question 2

what produces mucus?

Answer 2

goblet cells

Question 3

how are alveolar walls adapted to force out air?

Answer 3

• they contain elastic fibres which stretch during inspiration and recoil during expiration
• thin walls (one layer of sqaumous epithelial cells)
• close contact with blood capillaries so there is a short diffusion distance

Question 4

passive smoking definition

Answer 4

breathing in someone else’s cigarette smoke

Question 5

what are the three main components of cigarette smoke that pose a threat to human health?

Answer 5

• tar
• carbon monoxide
• nicotine

Question 6

what is tar?

Answer 6

a mixture of compounds that settles on the lining of the airways in the lungs and stimulates a series of changes that could lead to obstructive lung diseases and lung cancer

Question 7

what are carcinogens?

Answer 7

-cancer-causing compound that cause miutations in the genes that control cell division

Question 8

chronic bronchitis

Answer 8

• tar stimulates goblet cells and mucous glands to enlarge and secrete more mucus
• tar inhibits the cleaning action of the ciliated epithelium that lines the airways
• it destroys many cilia and the sweeping action of those that remain
• mucus accumulates in the bronchioles, which become obstructed
• mucus collects dirt, bacteria and viruses

Question 9

emphysema

Answer 9

• the inflammation of the constantly infected lungs causes phagocytes to leave the blood and line the airways
• the phagocytes release elastase
• this destroys the elastin in the walls of the alveoli, so there is a pathway for the phagocytes to reach the surface and remove bacteria
• elastin is responsible for the recoil of the alveoli when we breathe out
• the alveoli do not stretch
• the bronchioles collapse, trapping air in the alveoli, which often burst
• large spaces appear where the alveoli have burst
• this reduces the surface area for fas exchange
• the number of capillaries also decreases, so less oxygen is absorbed into the blood

Question 10

lung cancer

Answer 10

• tar contains several substances that are carcinogens
• these react, directly or via breakdown products, with DNA in epithelial cells to produce mutations
• these develop into a mass of cells, called a tumour
• as the cancer develops, it spreads through the bronchial epithelium and enters the lymphatic tissues in the lung

Question 11

what is the term for where cells break away and spread to other organs

Answer 11

metastasis

Question 12

nicotine

Answer 12

• absorbed very readily by the blood and travels to the brain within a few seconds
• stimulates the nervous system to reduce the diameter of the arterioles and to release adrenaline
• heart rate and blood pressure increase and there is a decrease in blood supply to the extremities of the body
• nicotine increases the risk of blood clotting
• it stimulates nerve endings in the brain to release dopamine

Question 13

carbon monoxide

Answer 13

• diffuses across the walls of the alveoli, into the bloods
• diffuses into red blood cells and combines with haemoglobin to form carboxyhaemoglobin
• this can lead to damage to the walls of the arteries, causing coronary heart disease and stroke

Question 14

cardiovascular diseases can be describes as…

Answer 14

multifactorial, meaning that many factors contribute to the development of these diseases