Topic 11 Flashcards
Features of gas exchange surfaces
Large surface area: faster diffusion of gasses
Thin walls: short diffusion distance
Good ventilation with air: diffusion gradient mantaines
Good blood supply: maintain high concentration gradient
The trachea: cartilage
Rings of cartilage around trachea (and bronchi)
- Cartilage: support airways and keep them open during breathing -> without them sides could collapse inwards when air pressure inside tubes drops
Cilia
Passage down to lungs lined with ciliated epithelial cells:
- Cilia (cytoplasm extensions) move mucus up passages towards nose and throat -> removing it from body
Mucus
Made: goblet cells
Traps: particles, pathogens and dust -> prevents them from entering the lungs
Ventilation of the lungs: Inhalation
Thorax volume increases and pressure decreases -> air drawn in
- External intercostal muscles: contract -> ribs move upwards and outwards
- Diaphgram: contracts -> flattens
- Internal intercostal muscles: relax
Ventialtion of the lungs: exhalation
Thorax volume decreases and pressure increases -> air forced out
- External intercostal muscles: relax -> ribs move downwards and inwards
- Diaphgram: relaxes -> rises
- Internal intercostal muscles: contract -> if air is being forced out (forced exhalation)
Composition of air: oxygen
Inspired air: 21%
Expired air: 16%
Composition of air: carbon dioxide
Inspired air: 0.04%
Expired air: 4%
Composition of air: nitrogen
Inspired air: % varies
Expired air: saturated
Reasons for differences in inhaled and exhaled air: oxygen
Removed from blood by respiring cells -> returns to lungs with lower concentration
Reasons for differences in inhaled and exhaled air: carbon dioxide
Produced by respiring cells into blood -> returns to lungs with higher concentration
Reasons for differences in inhaled and exhaled air: water vapour
Evaporated from lining of alveoli into air -> warmth of body
Test for carbon dioxide
Limewater: clear -> cloudy/milky when carbon dioxide bubbled through
Effect of exercise on breathing
Exercise: increases frequency and depth of breathing -> muscles working harder and aerobically respiring more needing more oxygen to keep up with energy demand
- Increased depth of breathing: so more carbon dioxide is removed as brain detects increased concentration of caebon dioxide in blood