Gas exchange

Question 1

Lungs

Answer 1

The lungs are in the thoracic cavity, surrounded by the pleural membrane, which encloses an airtight space. This space contains a small quantity of fluid to allow friction free movement. The lungs are ventilated by the movement of the diaphragm and ribs.

Question 2

Trachea, bronchi and bronchioles

Answer 2

Leading from the throat to the lungs is the trachea. At the base of the trachea are the bronchi which subdivide and branchs to form a bronchial tree in each lung. Each bronchus divides many times to form smaller bronchioles. Terminal bronchiole, divide to form narrower respiratory bronchiole which lead to the alveolar duct and the alveoli.

Question 3

Cartilage

Answer 3

In the trachea and bronchi it keeps the airways open, keeps air resistance low, prevents them from collapsing or bursting when the air pressure changes during breathing. In the trachea is a regular arrangement of C-shaped rings, in the bronchi there are irregular blocks.

Question 4

Smooth muscle

Answer 4

The bronchioles are surrounded by smooth muscle, which can contract or relax to adjust the diameter of these tiny airways. During exercise they relax to let more air in. The absence of cartilage makes this possible.

Question 5

Trachea

Answer 5

Cartilage, goblet cells, smooth muscle and cilia

Question 6

Bronchus

Answer 6

Cartilage, goblet cells, smooth muscle and cilia

Question 7

Terminal bronchiole

Answer 7

Smooth muscle and cilia

Question 8

Respiratory bronchiole

Answer 8

A few cilia

Question 9

Alveolar duct

Answer 9

Site of gas exchange

Question 10

Alveoli

Answer 10

Site of gas exchange

Question 11

Goblet cells role

Answer 11

Produce’s mucus which caches large particles which could be harmful to the gas exchange system. Mucus is a slimy solution of mucin, which is composed of glycoproteins with many carbohydrate chains which makes them sticky and able to trap inhaled particles.

Question 12

Goblet cells structure

Answer 12

The upper part of each goblet cell is swollen with mucin droplets which have been secreted from the cell. The rest of the goblet cell is slender

Question 13

Mucus glands

Answer 13

Makes mucus beneath the epithelium

Question 14

Cilia

Answer 14

Between the goblet cells.The continual beating of the cilia carries the mucus upwards towards the larynx, it is then swallowed so the pathogens are destroyed in the acid of the stomach, so that they dont harm the lungs

Question 15

Elastic fibre

Answer 15

Are in the alveolar walls, they stretch during inspiration and recoil during expiration to help force out air. Also allows them to expand more during exercise and increase their surface area.

Question 16

Structure of alveoli

Answer 16

Have a single layer of squamous epithelial cells as the alveoli walls. Blood capillaries are pressed against the alveoli walls, the capillary walls are one cell thick. Lots of capillary’s surround the alveoli, there are lots of alveoli meaning that there is a large surface area

Question 17

Gas exchange between alveoli and blood

Answer 17

O2 and CO2 diffuse quickly because the distance is small. A steep concentration gradient is maintained due to the constant breathing and blood flow. Breathing gives the alveoli a fresh air supply with a relatively high concentration of oxygen and a relatively low concentration of CO2. Blood in the lungs has a low concentration of oxygen and a high concentration of CO2, therefore the gases can move down the concentration gradient.

Question 18

COPD

Answer 18

Chronic obstructive pulmonary disease, includes asthma, emphysema and chronic bronchitis.

Question 19

Chronic Bronchitis

Answer 19

Tar stimulates goblet cells and mucus glands to enlarge and secrete more mucus. Tar inhibits the cleaning action of the cilia, it destroys or weakens them. Mucus accumulates in the bronchioles and may block them especially when foreign particles are trapped in them. When the damaged epithelial cells are replaced with scar tissue, the muscle surrounding the bronchioles becomes thicker causing the airways to narrow and making it hard to breathe, inflammation would occur. Infection can develop in the accumulated mucus and there may be white blood cells

Question 20

Emphysema

Answer 20

The inflammation of the constantly infected lungs causes phagocytes to leave the blood and line the airways. To reach the lining of the lungs from the capillary’s, they release the enzyme elastase, this destroys elastin in the walls of the alveoli. Without elastin the alveoli do not stretch and recoil, as a result the bronchiole collapse during expiration trapping air in the alveoli which often burst. Large spaces appear where they burst so there is less surface area for gas exchange. There are less capillary’s so less oxygen is absorbed into the blood.

Question 21

Lung cancer

Answer 21

Tar contains carcinogens which react with DNA in epithelial cells to produce mutations which lead to a tumour. As it develops it spreads through the bronchial epithelium and enters the lymphatic tissue in the lungs. Cells may break away and spread to other organs forming secondary tumours.

Question 22

Nicotine=Effect on cardiovascular system

Answer 22

Travels in the blood to the brain and reduces the diameter of the arterioles and release adrenaline from the adrenal glands. Heart rate and blood pressure increases, there is less blood in the extremities such as feet and hands, reducing their supply of oxygen. It also increases the risk of blood clotting as it makes platelets sticky. It is highly addictive and causes dopamine to be released. Can damage arterial linning

Question 23

Carbon monoxide= Effect on the cardiovascular system

Answer 23

Less oxygen is supplied to the heart muscles putting it under strain. Can damage the lining of the arteries. This damages may lead to the build up of fatty tissue and the reduction of blood flow. Coronary heart disease and stroke may result.