Paper 1 - Gas Exchange in Humans

Question 1

what separates thorax from lower body

Answer 1

diaphragm

Question 2

describe structure of lungs and trachea

Answer 2

air comes in through trachea
down to bronchus
bronchus splits into bronchioles
bronchioles have alveoli on them

Question 3

structure of thorax excluding lungs and trachea

Answer 3

pleural membranes around the lungs
ribs around lungs
intercostal muscles between the ribs
diaphragm at the bottom

Question 4

describe ventilation for breathing in

Answer 4

intercostal muscles and diaphragm contract (diaphragm moves down)
volume of thorax and lungs increases, decreasing the pressure so air from high pressure outside is drawn in

Question 5

describe ventilation for breathing out

Answer 5

intercostal muscles and diaphragm relax
volume of thorax and lungs decreases
this causes higher pressure than outside
therefore air is pushed out of lungs

Question 6

how are alveoli adapted

Answer 6

large surface area as there are many of them
one cell thin wall for lower distance of diffusion
permeable walls
great blood supply

Question 7

smoking effects on respiratory system

Answer 7

emphysema - less surface area for alveoli gas exchange as they fuse together
tar and chemicals damage ciliated epithelial cells which catch dust, mucus and bacteria so chest infections will be more likely
irritates bronchi and bronchioles which produces mucus which cannot be cleared by cilia as they are damaged which causes smoker’s cough and chronic bronchitis
carcinogens can also cause cancer