IB SL Biology 6.4 Gas Exchange 6.4 Gas Exchange 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide
between air in alveoli and blood flowing in adjacent capillaries.
6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry
out gas exchange.
6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a
moist surface inside the alveoli to prevent the sides of the alveolus adhering to
each other by reducing surface tension.
6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in
bronchioles. [Students should be able to draw a diagram to show the structure of
an alveolus and an adjacent capillary.]
6.4.U5 Muscle contractions cause the pressure changes inside the thorax that force air
in and out of the lungs to ventilate them.
6.4.U6 Different muscles are required for inspiration and expiration because muscles
only do work when they contract.
6.4.A1 Causes and consequences of lung cancer.
6.4.A2 Causes and consequences of emphysema.
6.4.A3 External and internal intercostal muscles, and diaphragm and abdominal
muscles as examples of antagonistic muscle action.
6.4.S1 Monitoring of ventilation in humans at rest and after mild and vigorous exercise.
(Practical 6) [Ventilation can either be monitored by simple observation and
simple apparatus or by data logging with a spirometer or chest belt and pressure
meter. Ventilation rate and tidal volume should be measured, but the terms vital
capacity and residual volume are not expected.]
Stephen Taylor Bandung International School http://sciencevideos.wordpress.com IB SL Biology 6.4 Gas Exchange Blog resource: http://tinyurl.com/2924a5l Click4Biology: http://tinyurl.com/2g2cn8e 1. Define the following: Ventilation Movement of air into and out of the lungs. (1) Gas exchange Cell respiration Deoxygenated Oxygenated 2. Explain the need for ventilation in humans. Size Humans are large, land-­‐based organisms that cannot exchange gas sufficiently with the air through diffusion alone. A central ventilation system allows gases to be exchanged with the blood and carried around the body to the cells that require it. Oxygen Carbon dioxide Concentration gradient 3. Deduce the number of membranes an oxygen molecule must pass through in order to enter an erythrocyte. Stephen Taylor Bandung International School http://sciencevideos.wordpress.com IB SL Biology 6.4 Gas Exchange 4.
Label the features of the alveoli and describe how they are adapted for their function. a. Dense network of capillaries b. Many invaginations and millions of alveoli – large surface area c. Moist membranes. d. Membranes only one cell thick. 5. Label this diagram of the human ventilation system. a. Trachea b. c. d. e. Stephen Taylor Bandung International School http://sciencevideos.wordpress.com IB SL Biology 6.4 Gas Exchange 6. Explain the method of ventilation of the lungs. Feature Inspiration Expiration Diaphragm Ribcage & EXTERNAL Lung volume Pressure in lungs Decreases, sucking air into the lungs Abdominal muscles intercostal muscles Ribcage & INTERNAL intercostal muscle Stephen Taylor Bandung International School http://sciencevideos.wordpress.com IB SL Biology 6.4 Gas Exchange 7. Fill out the chart below regarding causes and consequences of lung cancer and ephysema. Disease
Symptoms
• shortness of
Causes
Consequences
breath
• mild exercise
such as walking
becomes very
Emphysema
difficult
• No cure, usually
results in death
• Carcinogens
damage/mutate
the DNA of cells
• Damaged cells
begin to divide
Lung cancer
uncontrollably
forming tumors
Stephen Taylor Bandung International School http://sciencevideos.wordpress.com IB SL Biology 6.4 Gas Exchange 8. Distinguish between the structure and function Type 1 pneumocytes and Type 11 pneumocytes Stephen Taylor Bandung International School http://sciencevideos.wordpress.com