6.4

Question 1

define gas exchange

Answer 1

the exchange of oxygen and carbon dioxide b/w an organism and it’s environment by diffusion. in humans this occurs b/w the air in the alveoli and the blood in the capillaries

Question 2

define ventilation

Answer 2

the movement of air in and out of the lungs

Question 3

how is air carried into the lungs

Answer 3

through the trachea and bronchi into the alveoli and the bronchioles

Question 4

diagram of alveolus

Answer 4

Question 5

what are some important features of gas exchange surfaces

Answer 5

• have large surface area for diffusion
• are thin so that distance for diffusion is short
• are permeable to oxygen and carbon dioxide
• are moist so that gases can dissolve

Question 6

adaptations of alveoli

Answer 6

• lungs have millions of tiny alveoli which gives a very large total surface area over which gas exchange by diffusion occurs
• type 1 pneumocystes are extremely thin and permeable which form a single layer in the alveolus wall that reduces the diffusion distance of gases
• type 2 pneumocytes are cells which secrete a fluid to keep the inner surface of the alveoli moist so that oxygen can dissolve. they also secrete a surfactant which prevents the sides of the alveoli from adhering to each other by reducing the surface tension
• alveoli are covered by a network of capillaries which give a large surface area and are thin which reduces the diffusion distance of gases. blood flows continually through capillaries which maintains the concentration gradient for diffusion

Question 7

emphysema

Answer 7

• lung condition whereby lungs lose elasticity due to damage to alveoli
• alveoli are relaxed with large air sacs which greatly reduce SA over which gas exchange occurs
• common cause is smoking as this decreases number of phagocytes, which fight lung infections, and it increases amount of elastase which breaks down elastic fibres
• symptoms include fatigue, laboured breathing, shortness of breath

Question 8

inspiration vs expiration

Answer 8

Question 9

what is antagonistic

Answer 9

muscles that work in pairs and against each other

when one contracts the other relaxes

Question 10

monitoring ventilation

Answer 10

ventilation rate:
- the number of breaths (in & out) per minutes
- measured using observation of chest movements or using a spirometer

tidal volume:
- the volume of air breathed in/out at rest
- measured using spirometer only produced graph where volume of air can be measured

Question 11

what affects ventilation rate and lung capacity

Answer 11

lung capacity:
height - taller = higher lung capacity
smoking - decreases lung capacity
altitude - lower pressure = decreased

ventilation rate:
exercise - increases as more oxygen needs to be taken for respiration and more CO2 needs to be taken out

Question 12

lung cancer

Answer 12

lung cancer has high metastatic rate as receives rich blood supply

causes:
- smoking; tobacco contains mutagenic chemicals (passive smoking too)
- inhaling air pollution, asbestos, smog

symptoms:
- coughing up blood
- persistent cough
- chest pain