1.2 : transport of oxygen · 1.2 : transport of oxygen! transport of oxygen to the body cells! •...
TRANSCRIPT
1.2 : TRANSPORT OF OXYGEN What is DIFFUSION ?
v Gas molecules move from a place where there are many molecules (higher concentration) to a place with fewer molecules (lower concentration)
v Example ???
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Diffusion of OXYGEN from the ALVEOLI into BLOOD
CAPILLARIES
• Alveoli are surrounded by blood capillaries
• Inhalation : – fresh air (more
oxygen) is taken into the alveoli
– Oxygen from alveoli diffuses into the blood capillaries
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Diffusion of OXYGEN from the ALVEOLI into BLOOD
CAPILLARIES
• Oxygen combines with haemoglobin in red blood cells producing oxyhaemoglobin
• Blood that contains oxyhaemoglobin is called oxygenated blood (bright red)
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Diffusion of OXYGEN from the ALVEOLI into BLOOD
CAPILLARIES
• At the same time, CO2 in the blood capillaries (higher concentration) diffuses into the alveoli (lower concentration) to be expelled during exhalation
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Why ALVEOLUS allows the diffusion of gases?
Present in large numbers
in the lungs
Richly supplied
with blood capillaries
Moist wall
One-celled thick wall
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Transport of OXYGEN to the BODY CELLS
• Oxygenated blood surrounding the alveoli first flows to the heart
• Heart pumps the blood out to the body cells which require oxygen
Alveolus
Body cells Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Transport of OXYGEN to the BODY CELLS
• Gases exchange (diffusion) happens between CO2 and O2 – Body cells
receive O2 and CO2
– Blood capillaries release O2 and receive CO2
– Blood capillaries carry deoxygenated blood (dull colour)
Prepared by Ms Sue Soh
1.2 : TRANSPORT OF OXYGEN Transport of OXYGEN to the BODY CELLS
• Deoxygenated blood is carried back to the heart and then to the blood capillaries surrounding the alveoli in the lungs
• Deoxygenated blood releases CO2 to the alveoli & absorbs O2, forming oxygenated blood again.
Prepared by Ms Sue Soh