11. Gas Exchange in Humans Flashcards
Function of cartilage and trachea
supports trachea and prevents it from closing
without it, the sides would collapse inwards when air pressure inside tube drops
features of efficient gas exchange surfaces in humans (4)
- large SA
- thin surface = shorter diffusion dist
- good blood supply
- good ventilation with air
Explain the differences in composition between inspired and expired air
INSPIRED, EXPIRED
Oxygen 21%, 16%
O2 is absorbed into the blood in alveoli; used in respiration - CO2 produced
CO2 0.04%, 4%
released from blood (CO2 produced as a waste product) at alveoli (conc in blood > air)
- diffuses out in lungs before exhaled
Nitrogen 78%, 78%
body doesn’t absorb - too stable
Water Vapour lower, higher
evaporates from moist living alveoli, result of the warmth of the body
Test for carbon dioxide
limewater = Ca(OH)2
+ve result/ CO2 present - turns cloudy/milky
-ve - remains colourless
Role of goblet cells (2)
found in TRACHEA & BRONCHI
produce mucus into respiratory tract
role of mucus (2)
- produced by goblet cells
- traps bacteria, dust, particles
role of cilia
beat and
push the mucus away from the lungs towards the throat
Ventilation of the lungs - in
Breathing in (inhalation/inspiration)
- EXTERNAL INTERCOSTAL MUSCLES CONTRACT, internal - relax
- ribcage moves up and out
- DIAPHRAGM CONTRACTS and flattens = pushes abdominal muscles inwards
- vol of thorax increases
- PRESSURE inside thorax + conc of air decrease
- air diffuses into lungs
conc of air in lungs < air
Ventilation of the lungs - out
Breathing out (exhalation/exspiration)
- INTERNAL INTERCOSTAL MUSCLES CONTRACT
- ribcage moves down and in
- DIAPHRAGM RELAXES and becomes dome-shaped
- vol of thorax decreases
- PRESSURE inside thorax increases
- air is forced out
= passive process
Explain the link between physical activity and rate and depth of breathing
increased carbon dioxide concentration in the blood, detected by the brain, causing an increased rate of breathing
