gas exchange in humans (module 3)

Question 1

what is the pathway for air entering the GE system?

Answer 1

mouth -> trachea -> bronchus -> bronchioles -> alveoli

Question 2

What is the importance of the gas exchange system?

Answer 2

• provide O2 for aerobic respiration
• ATP required for active transport and phosphorylation
• remove CO2 from body

Question 3

What are the adaptations of trachea?

Answer 3

• flexible
• cartilage to prevent collapse when air pressure falls
• lined with ciliated epithelia
• cilia has wafting movement to remove mucus
• unwanted bacteria transported to stomach to avoid infection

Question 4

what occurs during inspiration (inhalation/breathing in)?

Answer 4

• diaphragm contracts
• external intercostal muscles contract (opposite for internal)
• ribcage pulled upwards and outwards
• volume of thorax increases and pressure reduces
• atmospheric air greater than pulmonary pressure so air forced into lung

Question 5

what occurs during expiration (exhalation/breathing out)?

Answer 5

• diaphragm relaxes
• internal intercostal muscles contract (opposite for external)
• ribcage pulled inwards and downwards
• volume of thorax decrease and pressure increase
• pulmonary pressure greater than atmospheric air so air forced out of lungs

Question 6

how does ficks law apply to alveoli?

Answer 6

• thin exchange surface as alveolar epithelium one cell thick
• large surface area as millions of alveoli are packed together
• steep concentration gradient maintained by constant blood flow and ventilation