Essential Idea
The lungs are actively ventilated to ensure that gas exchange can occur passively.
Understandings
Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.
Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange.
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.
Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles.
Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
Different muscles are required for inspiration and expiration because muscles only do work when they contract.
Applications
Causes and consequences of lung cancer.
Causes and consequences of emphysema.
External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action.
Skills
Monitoring of ventilation in humans at rest and after mild and vigorous exercise (VIDEO). (Practical 6)
Guidance
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.
Students should be able to draw a diagram to show the structure of an alveolus and an adjacent capillary.
Key Vocabulary
Anatomy
Trachea
Bronchi
Bronchioles
Alveoli
Pneumocyte
Type I
Type II
Surfactant
Surface tension
Capillary
Concentration gradient
Ventilation
Pressure gradient
Inspiration
Expiration
Antagonistic muscles
Internal & external intercostals
Diaphragm & abdominals
Diseases
Lung cancer
Emphysema
Respiratory measurements
Ventilation rate
Tidal volume
Textbook Reading and/or Activities
Click HERE for a pdf of chapter 6.
Pages 307-314
Challenge Yourself (p.309)
Challenge Yourself (p.310)
Figure 6.14 (p.311)
TOK (p.314)
Exercises (p.314)
Notes
A detailed set of notes, prepared by Stephen Taylor, examining U1-U6.
i-Biology Study Questions (Not available)
A series of questions, prepared by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.
A detailed set of notes, prepared by Chris Paine, examining all of the IB learning expectations.
A series of questions, prepared by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.
Learning Activities
This interactive tutorial, prepared by National Geographic, will help you learn the lung's anatomy as well as better understand the processes by which oxygen is obtained from the atmosphere and carbon dioxide is removed from our body.
Draw, Label and Annotate the Respiratory System
This activity will challenge your ability to prepare a drawing as outlined in the Guidance section to the left.
Lab - Monitoring Ventilation in Humans (Practical 6)
Assignment outline found on p.310-311 in the IB Bio. etext.
Lab - Heart and Lung Dissection
This activity will help you better understand the structures and their respective functions of the mammalian heart and lungs.
Supplemental Reading
Title
Description
This video outlines many of the structures and processes identified in the IB expectations in addition to some others.
This video outlines the process by which smoking affects the lungs; describing its association with emphysema and lung cancer.
Should Watch Videos
This video outlines the process of ventilation in the lungs and gas exchange between the alveoli and the capillaries.
This video outlines the anatomy and physiology of the heart and lungs as well as the manner in which they work together to supply the body with resources and remove wastes.
Must Watch Videos