Chapter 11

Question 1

Describe the features of gas exchange surfaces

Answer 1

large surface area: faster diffusion
thin surface: smaller diffusion distance
good blood supply: to transport oxygen to respiring tissues and bring carbon dioxide from those tissues
good ventilation with air: creates & maintains conc. gradient

Question 2

Describe how the breathing system works:

Answer 2

to suck in air, the volume of the lungs needs to be increased to decrease the pressure – contracted external intercostal muscles pulling the ribcage upward and outward & muscle of diaphragm contract moving downwards increasing thorax volume

O₂ moves into the the nasal cavity and moves into the trachea which splits into 2 bronchi which splits into multiple bronchioles in the lungs which end in air sacs (alveoli) which are surrounded by blood capillaries which bring a blood supply which the O₂ diffuses into and is transported to organ tissues – opposite pathway of CO₂ The lining of the alveoli walls are also moist so the gases can easily dissolve & diffus

larynx – voice box containing vocal cords

Question 3

State the function of cartilage in the trachea

Answer 3

Prevent it from collapsing when pressure decreases

Question 4

Explain the differences in composition between
inspired and expired air

Answer 4

Inspired air: 21% O₂ | 0.04% CO₂ | 79% N₂ | some water (g)
Expired air: 16% O₂ | 4% CO₂ | 79% N₂ | some more water (g)

amount of O₂ decreases as O₂ diffuses into the bloodstream for aerobic respiration, amount of CO₂ increases as it is a waste product of respiration that is excreted, N₂ stays constant as it is not produced/used by the body, expired air has more water vapour because moisture evaporates from the surface of the alveoli

Question 5

Testing for carbon dioxide in inspired and expired air

Answer 5

!! refer to diagram 11.4 !!
limewater turns milky when CO₂ is added
when breathing in the air is sucked from test-tube A and exhaling air is blown to test tube B into the limewater which turns from colorless to milky

Question 6

Describe protection of the gas exchange system from pathogens and particles

Answer 6

pathogens/particles in the air can get into our body as we inhale – to prevent this the trachea’s epithelium (and bronchi) is lined with ciliated & goblet cells

goblet cells – secretes sticky mucus which traps pathogens and dust particles
ciliated cells – hair like cilia which sweep the mucus (containing the pathogens and particle) up to the back of the throat away from the lungs preventing them from entering the alveoli

Question 7

How can rate and depth of breathing be measured

Answer 7

a spirometer records the volume of air being inspired and expired by a person breathing

Question 8

Explain the link between physical activity and
the rate and depth of breathing

Answer 8

physical activity needs muscle contraction which needs energy which needs aerobic respiration which produces CO₂ as a waste product, as physical activity increases the amount of CO₂ produced builds up in muscle cells and diffuses into the bloodstream quickly – increase in blood CO₂ concentration is detected by the brain which stimulates the external intercostal muscles and diaphragm to contract and relax more rapidly to increase rate and depth of breathing to excrete CO₂ faster