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Gas Exchange in Humans - Coggle Diagram
Gas Exchange in Humans
Gas Exchange Surfaces
Thin surface
Short distance to diffuse (one cell thick)
Large surface area
Many molecules can diffuse at once/More alveoli
Good ventilation
Regular fresh air supplies keep up concentration gradients for oxygen and carbon dioxide.
Good blood supply
Gases can be carried to/from the cells that need/produce them
Moist
Allow gases to dissolve, ready for diffusion
Structure of the Lungs
The lung contains a diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries
Cartilage (in the trachea): prevents the trachea from collapsing during the absence of air and protects it by keeping it open.
Ribs: to protect vital organs and blood vessels and expand and contract (and efficient breathing).
Intercostal (internal & external) muscles: situated between the ribs that create and move the chest wall.
Diaphragm: produces volume and pressure changes in the thorax, leading to the ventilation of the lungs.
Composition of Breathing Dry Air
Inspired Air
Oxygen-2
Carbon Dioxide-0.04%
Nitrogen-78%
Water Vapour-Lower
External intercostal muscles contract – pulls ribcage upwards and outwards
Diaphragm muscles contract – the diaphragm moves downwards, and the volume of the thorax increases
Atmospheric Pressure > Pressure in Thorax
Air moves into the lungs
Expired Air
Oxygen-16%
Nitrogen-78%
Carbon Dioxide-16%
Water Vapour-HIgher
External intercostal muscles relax – ribcage falls downwards and inwards
Diaphragm muscles relax – return to a dome shape, and the volume of the thorax decreases
Atmospheric Pressure < Pressure in Thorax
Air moves out of the lungs
Test for CO2: Add CO2 through limewater. +ve result = turns cloudy
Internal intercostal muscles are used in coughing and sneezing.
Mucus & cilia: goblet cells produce sticky mucus to trap and eliminate particulate matter and microorganisms.
Ciliated cells have cilia, little hairs which sweep/beat back and forward in a coordinated way to brush mucus up the lungs into the mouth.
Physical Activity on Breathing
Physical activity increases the breathing rate – more respiration - and higher CO2 concentration in the blood.
This is measured with a spirometer to produce a spirogram.
During exercise, tissues respire at a higher rate; the change in breathing volume and rate helps keep CO2 concentration and pH safe.
Oxygen Debt
It is the extra oxygen that is needed after anaerobic respiration has taken place, in order to break down the lactic acid produced.
How it is removed :
continued fast heart rate to transport lactic acid in blood from the muscles to the liver
Continued deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid
Aerobic respiration of lactic acid in the liver. ( the liver breaks down the lactic acid into glucose using oxygen)